WO2022034225A2 - An electrode material and a battery as well as their manufacture - Google Patents

An electrode material and a battery as well as their manufacture Download PDF

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Publication number
WO2022034225A2
WO2022034225A2 PCT/EP2021/072633 EP2021072633W WO2022034225A2 WO 2022034225 A2 WO2022034225 A2 WO 2022034225A2 EP 2021072633 W EP2021072633 W EP 2021072633W WO 2022034225 A2 WO2022034225 A2 WO 2022034225A2
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WIPO (PCT)
Prior art keywords
metal
battery
tio
ions
ion
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PCT/EP2021/072633
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French (fr)
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WO2022034225A3 (en
Inventor
Robert Corkery
Anders TEIGLAND
Andreas Westermoen
Hjørdis SKÅR
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Tiotech A/S
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Priority claimed from SE2050954A external-priority patent/SE544708C2/en
Priority claimed from SE2050955A external-priority patent/SE544707C2/en
Priority claimed from SE2150677A external-priority patent/SE546073C2/en
Application filed by Tiotech A/S filed Critical Tiotech A/S
Publication of WO2022034225A2 publication Critical patent/WO2022034225A2/en
Publication of WO2022034225A3 publication Critical patent/WO2022034225A3/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/04—Oxides; Hydroxides
    • C01G23/047—Titanium dioxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/04—Oxides; Hydroxides
    • C01G23/047—Titanium dioxide
    • C01G23/053—Producing by wet processes, e.g. hydrolysing titanium salts
    • C01G23/0536—Producing by wet processes, e.g. hydrolysing titanium salts by hydrolysing chloride-containing salts
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G23/00—Compounds of titanium
    • C01G23/04—Oxides; Hydroxides
    • C01G23/047—Titanium dioxide
    • C01G23/08—Drying; Calcining ; After treatment of titanium oxide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/50—Solid solutions
    • C01P2002/52—Solid solutions containing elements as dopants
    • C01P2002/54—Solid solutions containing elements as dopants one element only
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency
    • Y02P20/133—Renewable energy sources, e.g. sunlight

Definitions

  • the invention relates to a method for manufacturing a component material of a battery electrode.
  • the component material of the battery electrode as well as a battery comprising the component material are encompassed .
  • titanate bronze precursor material which can be used in the manufacture of a battery.
  • the known methods according to the prior art may require a) an expensive and complicated hydrothermal process step operating at elevated temperature, pressure and high alkalinity, with a limited scale up capacity of the pressure vessels, or b) a very high temperature process step, greater than approx. 800 °C to make a bronze precursor or c) making TiO 2 (B) from a titanium glycolate precursor which generally involves use of dangerous oxidizers such as hydrogen peroxide. Still there is the problem of anatase formation instead of formation of the desired bronze form of titanium dioxide.
  • WO 2020/165419 as well as SE543124 disclose a method for manufacturing a structure of a titanium compound selected from the group consisting of sheets, wires and tubes .
  • TiCd (B) bronze material It has been discovered that it is possible to improve the manufacture of a TiCd (B) bronze material. It has been discovered that presence of certain metal ions can stabilize the material during the process and in particular stop or at least decrease the transition to the anatase phase of titanium dioxide during the manufacturing process. Anatase is less preferred compared to the bronze form. The material is treated to adjust the content of certain metal ions during the manufacturing process.
  • a method for manufacturing a component material of a battery electrode comprising Tith, wherein the TiO 2 comprises a fraction of TiO 2 (B) , titanium dioxide in bronze phase
  • the method comprising the steps of : a) providing an aqueous solution comprising TiOCl 2 , HC1, and an alpha-hydroxy acid, b) increasing the pH of the solution until a precipitate is obtained, wherein the temperature is above 0 °C and below 55 °C, and c) calcining the obtained precipitate during a time range of 5 minutes to 48 hours at a temperature in the interval 110-600 °C to obtain a calcined material comprising the titanium dioxide bronze material.
  • a component material of a battery electrode comprising TiO 2 , (B) wherein the TiO 2 c(Bo)mprises a fraction of TiO 2 (B(B)) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AW metal - 0.10*X) ⁇ R ⁇ (0.82*AW metal - 0.10*X) , wherein AW metal is the atomic weight of the metal and X is the metal valence.
  • a battery comprising at least one electrochemical cell, said at least one electrochemical cell comprises at least two electrodes 1,2 and at least one electrolyte 7, wherein at least one of the electrodes 1,2 comprises a) a material comprising TiO 2 , wherein the TiO 2 ( cBo)mprises a fraction of TiO 2 (B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, b) at least one conducting material, and c) at least one binder, wherein for the material the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AW metal - 0.10*X) ⁇ R ⁇ ( 0.82*AW metal - 0.10*X) , wherein AW metal is the atomic weight of the metal and X is the metal valence .
  • the present invention provides a more cost efficient material and battery.
  • Another advantage is that a battery will have an improved capacity since the fraction of TiO 2 (B) is high.
  • the content of metal ions in the material stabilizes the material so that a high fraction of TiO 2 (B) is ensured. Further this has the potential to give a much higher charging rate compared to the batteries according to the prior art.
  • the long-term performance of the battery improves compared to the prior art.
  • Figure 1 shows representative Raman spectra of hydrogen titanate powders from example 1, where hydrogen was exchanged for Na in increasingly concentrated NaOH solutions followed by filtering, drying at room temperature and heating to 400 °C in air.
  • the peak at 'A' near 150 cm -1 in the 0 M spectrum is assigned to the anatase E g ( 1 ) vibrational mode (Gariola et al. Physical Review B 81, 174305, 2010) .
  • the peak at 'B' near 200 cm 1 is assigned to the B g (2) vibrational mode of bronze (or bronze-like) phase of titanium dioxide (Ben Yahia et al. The Journal of Chemical Physics 130, 204501, 2009)
  • a and B are the same in all figures.
  • the bronze stability indicator is plotted in later Figures at different temperatures and NaOH exchange concentrations .
  • Figure 2 shows representative Raman spectra of hydrogen titanate powders, from example 1 where hydrogen was exchanged for Na in increasingly concentrated NaOH solutions followed by filtering, drying at room temperature and heating to 450 °C in air.
  • Figure 3 shows representative Raman spectra of hydrogen titanate powders from example 1 where hydrogen was exchanged for Na in increasingly concentrated NaOH solutions followed by filtering, drying at room temperature and heating to 500 °C in air. This figure also clearly shows the amount of stabilization against the transition to anatase at 500 °C is positively correlated to the amount of Na exchanged into the titanate. This is also seen in figures 4 and 5 below.
  • FIG. 4 shows bronze stability indicator (BSI) value as a function of increasing NaOH concentration in the exchange solution for a range of thermal treatment temperatures applied to the exchanged powders.
  • the BSI is calculated from data from example 1. Note that as the concentration of the exchange solution goes up, the amount of sodium exchanged into the titanates also goes up since there was a complete or nearly complete exchange indicated by drop in pH after exchange (provided the titanate precursor is not saturated with Na) , independent of the starting NaOH concentration. Here the BSI clearly goes up as a function of sodium exchange into the titanate.
  • Figure 5 shows the same data as in Figure 4 was replotted to show BSI as a function of temperature for a range of exchange solution concentrations.
  • the stability of bronze or bronze-like phase is stabilized in an increasingly positive way as the amount of Na in the exchange solution was increased.
  • FIG. 6 shows a schematic drawing of a battery comprising at least one electrochemical cell, said at least one electrochemical cell comprises two electrodes 1,2 and an electrolyte 7.
  • the battery is according to the invention and comprises a working anode 1, a counter electrode 2, a separator 3, a lower casing 4, an upper casing 5, and a gasket 6.
  • the working anode 1 comprises an electrode material made by the method according to the invention.
  • the casing 4, 5 encloses the electrolyte 7.
  • Figure 7 shows a flow chart of the method according to the present invention.
  • Figure 8 is a graph showing weight % of stabilizing metal versus Ti/M ratio.
  • Figure 9 shows calculated theoretical capacity versus Ti/M atomic ratio R for various stabilizing metals.
  • Figure 10 shows the measured specific capacity vs the number of cycles for the measurement of example 3.
  • Figure 11 shows representative Raman spectra of niobium doped hydrogen titanate powders where where hydrogen was exchanged for Na in increasingly concentrated NaOH solutions followed by filtering, drying at room temperature and heating to 550 °C in air from example 4.
  • Figure 12 shows the measured specific capacity vs the number of cycles for the measurement of a half cell constructed using an electrode made from the first slurry of example 4.
  • Figure 13 shows the measured specific capacity vs the number of cycles for the measurement of a half cell constructed using an electrode made from the second slurry of example 4.
  • Figure 14 shows the measured specific capacity vs the number of cycles for the measurement of a half cell constructed using an electrode made from the second slurry of example 4.
  • Figure 15 shows an experimental result as described more in detail in the experimental section.
  • Figure 15 shows the specific capacity of a battery cell comprising the electrode material manufactured according to the invention, when the battery is cycled a number of times.
  • the capacity at cycle 3 was approximately 92 mAh/g at C/10 and an approximately stable capacity of 80 mAh/g.
  • Figure 16 shows a result from the same cell as in figure 15.
  • the specific capacity as well as the Coulombic efficiency can be seen as a function of the number of cycles of the battery.
  • the Coulombic efficiency is the lower line. It can be seen that the Coulombic efficiency levelled out at 100% after about 5-10 cycles out to 250 cycles at C/2.
  • 'Bronze precursor' as used in the description and the claims denote layered titanate compounds that are precursors to bronze and have a particular structure, whereas other precursor titanate compounds may transform directly to anatase. Titanate is a titanium dioxide compound. The distinction between these precursors that lead to bronze or anatase has been discussed in detail by Feist and Davies, J. Solid State Chem. 101, 275-295
  • layered bronze precursor titanates of formula A 2 Ti n O 2n+i comprise titanate sheets that stack in an ABA sequence. Also considering the water molecules, the general formula is A 2 Ti n O 2n+1 ⁇ mH 2 O . n is an integer from 3 to 6, m is a number from 0 to 2.5. Those with an AAA sequence cannot transform to bronze.
  • the step size is defined by n.
  • H 2 Ti 3 O 7 , K 2 Ti 4 O 9 , H 2 Ti 4 O 9 .H 2 O and Cs 2 Ti 5 O 11 H 2 Ti 5 O 11 .H 2 O are step 3, 4 and 5 layered titanates with ABA sequence, respectively.
  • AAA and ABA refers to the stacking sequence of titanates as normally referred to within the scientific literature involving titanates.
  • anatase precursor' as used in the description and the claims denotes anatase precursors including non-ABA stacked layered compounds of titanium oxygen and hydrogen, hydrated amorphous titanium oxides or orthorhombic lepidocrocite-like layered titanates of formula H x Ti 2-x [ ] x/4 O 4 , where [ ] represents a crystal vacancy with sheets of flat rather than corrugated TiOe octahedra. These transform directly to anatase without first converting to bronze.
  • the transition temperature of bronze to anatase is lowered due to the nucleation of anatase from anatase precursors and subsequent destabilization of bronze by these anatase seeds, and that addition of Na or other suitable ions prevent the formation of anatase via formation of stable metal titanates directly from the anatase precursors, and that any excess Na trapped in the bronze precursors transforms to a bronze-like structure.
  • Sodium or other stabilizing ions may not need to be added separately, they may be included as controlled residuals from incomplete ion exchange of the metal titanate precursor. Where the process comprises removal of metal ions such a removal can be incomplete and not full, so that an amount of metal ions remain in the material .
  • Raman spectroscopy is used as a measurement technique to study TiO 2 and its different phases.
  • the 'bronze stability indicator' is calculated by dividing the intensity for the B g (2) bronze peak located in the interval 190 - 205 cm -1 minus the background intensity by the intensity for the E g ( 1 ) anatase peak located in the interval 140 - 160 cm -1 minus the background intensity and then the resulting ratio is divided with a normalization factor which is calculated as the intensity of the E g ( 1 ) anatase peak minus the background intensity divided by the intensity for the B g ( 2 ) bronze peak minus the background intensity for pure TiO 2 (B) , wherein the background intensity as calculated as the average intensity in the region with a wavenumber higher than the zero-peak and lower than the intensity originating from the sample.
  • the exact location of the E g ( 1 ) anatase and B g (2) bronze peaks may vary somewhat depending on the conditions.
  • the peaks can be for instance at 201 and 148 cm -1 respectively.
  • the skilled person can easily identify the peaks and read the intensity at the peak and use that peak intensity for the calculation.
  • Regarding the background it is the intensity for the background between the zero-peak and the intensity from the sample, i.e. the wave number is higher than 0 and lower than the first intensity originating from the sample. This background normally corresponds to the intensity at 75 cm -1 .
  • a corresponding formula would be (Peak height Bg(2 ) - background) / ( ( Peak height Eg(1) - background) *NF) .
  • the value is then normalized with a normalization factor NF.
  • NF (Peak height Bg(2) ) / (Peak height Eg (i) ) , for pure bronze.
  • a normalization factor around 1.3 can be expected. Effects such as fluorescence may complicate the calculation of the BSI, so that the measurements are suitably done without significant influence of fluorescence on the spectra.
  • a 'clear solution' is defined as being nearly or completely transparent to visible light with little or no detectable cloudiness or scattering of visible light by undissolved titanic acid and may be determined by shining a visible light laser through the solution until it passes straight through the solution with little to no detectable scattering of visible light from within the solution to the naked eye. Alternately, it may be detected in practise when ordinary 12 point printed text is resolved through a 10 cm path-length of the solution held in a glass pipe.
  • a 'ratio' is used to describe a relation between different quantities.
  • a ratio between a and b is expressed as a:b, which is interpreted as a/b, i.e. a divided by b so that the ratio is equal to a divided by b .
  • 'Suspension' as used throughout the description are solid particles in a liquid medium.
  • the particles are at least partially so large that they settle after some time due to gravity.
  • the solid particles in the suspension can be for instance a precipitate.
  • 'Wt%' denotes percentage by weight. All percentages and ratios are calculated by weight unless otherwise clearly stated. For instance the ratio of Ti:metal ratio is not expressed in wt%, instead the ratio is based on the number of atoms of Ti to the number of atoms of metal. The same applies to the ratio Ti:Nb, i.e. that it is the number of atoms of Ti to the number of atoms of Nb . Mass and weight for the calculation of wt% as well as other quantities are as defined in ISO 80000-4:2019.
  • a method for manufacturing a component material of a battery electrode comprising TiO 2 , wherein the TiO 2 comprises a fraction of TiO 2 (B) , titanium dioxide in bronze phase
  • the method comprising the steps of : a) providing an aqueous solution comprising TiOCl 2 , HC1, and an alpha-hydroxy acid, b) increasing the pH of the solution until a precipitate is obtained, wherein the temperature is above 0 °C and below 55 °C, and c) calcining the obtained precipitate during a time range of 5 minutes to 48 hours at a temperature in the interval 110-600 °C to obtain a calcined material comprising the titanium dioxide bronze material.
  • the aqueous solution comprising TiOCl 2 is provided by at least partial hydrolysis of TiCl 4 .
  • the aqueous solution comprising TiOCl 2 is provided by dissolving at least one titanic acid with the general formula TiO x (OH) 4-2x , wherein x is 0 or 1, in an aqueous solution comprising at least one compound selected from the group consisting of TiOCl 2 , TiCl 4 , and HCl so that a clear solution is obtained, while keeping the temperature below 30 °C.
  • the at least one titanic acid is made from TiOCl 2 by addition of an aqueous solution of a base until precipitation.
  • the latter approach has the advantage that the process is easier to control, in particular in large scale. More in particular it is possible to measure and control the acidity with high accuracy.
  • the acidity is the ability to donate protons in an aqueous solution, i.e. the acidity is the amount of acids.
  • the obtained precipitate is washed in water between steps b) and c) .
  • the calcination is carried out so that the organic material including the alpha-hydroxy acid is removed at least essentially removed so that the effect of any remaining organic material is negligible. Further the calcination should be carried out so that a rearrangement occurs in the material in such a way that the fraction of anatase is minimized and the fraction of titanium dioxide in bronze form is maximized. This is normally done by choosing a lower temperature in the interval 300-450 °C together with a longer calcination time, or a higher temperature in the interval 300-450 °C together with a shorter calcination time. A skilled person can in the light of the description and the appended examples choose a suitable temperature and time for the calcination. A time range for the calcination is in one embodiment 5 minutes to 48 hours.
  • the method is carried out at a pressure p being ambient pressure p ambient pressure ⁇ 20%. This is Construed to mean 0.8p ambient pressure ⁇ p ⁇ 1.2 p ambient pressure - Ambient pressure is in one embodiment 101325 Pa.
  • pH is increased in step b) by addition of NaOH.
  • the at least one alpha hydroxy acid is citric acid.
  • the aqueous solution provided in step a) is clear. Clear is as defined above. This has the advantage that it is ensured that any reaction giving the TiOCl 2 is more complete.
  • the precipitate is dried and optionally ground between steps b) and c) .
  • the precipitate is dried at a temperature of between 300 and 500 °C.
  • the precipitate is dried for a time period of between 1 and 2 h.
  • step b) further comprises the washed precipitate being suspended in an aqueous acid solution with a pH lower than 3 and stirred to replace at least a part of the cations in the titanium dioxide with H + ions to obtain a suspension of acid exchanged titanium dioxide.
  • the stirring is carried out during 2 - 24 hours.
  • the acid is a mineral acid.
  • the acid is HC1.
  • the concentration of the acid is 0.02 to 0.5 M.
  • step b) further comprises the acid exchanged titanium dioxide being washed by repeated centrifugation and decantation.
  • the obtained precipitate in step b) is separated from the remaining liquid between steps b) and c) .
  • step a) or b) no transition metal ions except titanium ions are added in step a) or b) .
  • At least one type of ions selected from the group consisting of Na + , K + , Rb + and Cs + are added at any point before step c) .
  • Such ions have a stabilizing effect, but too high concentration of these ions can reduce the efficiency of the material in a battery.
  • Such ions have the effect of delaying or decreasing the transition to anatase.
  • Lighter ions are preferred in order to make the final material more lightweight. Thus, for instance Na is preferred over Cs .
  • Nb-ions are added at any point before step b) .
  • Nb-ions could be added up to an amount corresponding to a ratio of 8: 1 calculated as the ratio between the weight of Titanium ions to Niobium ions.
  • the Nb-ions have the advantage of improving the conductivity.
  • the pH in step b) is increased also after the precipitate is obtained and wherein the pH is increased to a value in the range 7-10. This has the effect that the charge of certain groups of the titanium dioxide is reversed to become negative so that positive ions such as Na + -ions are attracted to the material .
  • the calcination in step c) is carried out at a temperature in the interval 300-450 °C.
  • the lower limit for the temperature interval is one temperature selected from the group consisting of 110 °C, 260 °C, 270 °C, 300 °C, 350 °C and 400 °C.
  • the upper limit for the temperature interval is one temperature selected from the group consisting of 600 °C, 550 °C, 500 °C and 450 °C. Any one temperature selected from the lower limits can freely be combined with any one temperature selected from the upper limits. Thus a lower limit is selected from the above mentioned lower limits and an upper limit is selected from the above mentioned upper limits and those limits are combined to an interval.
  • intervals include but are not limited to: 110-600 °C, 260-500 °C, 350-450 °C, 400-450 °C, 400-600 °C, and 110-450 °C.
  • the calcined material is washed to reduce the content of soluble ions and then dried.
  • At least one conducting material and least one binder is added to the calcined material to obtain an electrode material for a battery .
  • At least one conducting material and least one binder is added to the calcined material to obtain an electrode material for a battery in and/or after step c) .
  • the conducting material is carbon black.
  • the electrode material comprises about 90 wt% of TiO 2 bronze, 6-7 wt% carbon black and 4-3 wt% binder.
  • at least one precursor for a conducting material is added before the calcination to obtain an electrode material for a battery. Such a conducting material should then be able to withstand the calcination. A precursor of a conducting material shall break down to a conducting material during the calcination.
  • the conducting material is added after the calcination step.
  • the binder is added before the calcination step.
  • the binder is added after the calcination.
  • the calcined material is mixed with binder and conducting material after the calcination. At least one precursor for a conducting material is added before the calcination to obtain an electrode material for a battery .
  • the conducting material is carbon black.
  • the at least one conducting material, the at least one binder and the calcined material are mixed in a slurry.
  • the slurry is an aqueous slurry and water is added.
  • the content of the calcined material in the electrode material is 70-90 wt%.
  • a slurry for making a battery electrode comprising at least one conducting material, at least one binder and a calcined material manufactured according to the method of the first aspect .
  • a BET specific surface area of the calcined material according to ISO 9277 is in the range of 2-30 m 2 /g.
  • the aqueous mixture obtained in step a) comprises a titanium dioxide bronze precursor with the general formula A2Ti n O 2n+1 • mH20, and an anatase precursor, wherein A is hydrogen or a metal in cationic form, n is an integer from 3 to 6, m is a number from 0 to 2.5, wherein the content of metal ions is in the range 1.5 to 30 wt%, wherein the metal ions are at least one type of ions of a metal selected from the group consisting of sodium, potassium, rubidium, caesium, rubidium, zinc, lanthanum, and tin.
  • the aqueous mixture obtained in step a) comprises a titanium dioxide bronze precursor with the general formula A2Ti n O 2n+1 • mH20, and an anatase precursor, wherein A is hydrogen or a metal in cationic form, n is an integer from 3 to 6, m is a number from 0 to 2.5, wherein the content of metal ions is in the range 1.5 to 30 wt%, wherein the metal ions are at least one type of ions of a metal selected from the group consisting ofrare earth metals, alkaline earth metals, transition metals, sodium, potassium, rubidium, caesium, zinc, lanthanum, indium, tin, lead, bismuth, calcium, magnesium, titanium, niobium, rubidium, lithium, silver, copper, and cadmium.
  • A is hydrogen or a metal in cationic form
  • n is an integer from 3 to 6
  • m is a number from 0 to 2.5
  • the content of metal ions is in
  • the temperature in step c) is in the interval 300-500 °C and content of metal ions is in the range 1.5 - 30 wt% . In one embodiment of the first aspect, the temperature in step c) is in the interval 300-400 °C and content of metal ions is in the range 1.5 - 6 wt%.
  • the content of metal ions is adjusted to the desired value by ion exchange .
  • the content of metal ions is adjusted by additions of the desired metal ions during the manufacture of the aqueous mixture.
  • the manufactured component material of the battery electrode comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition (0.029*AW metal - 0.10*X) ⁇ R ⁇ ( 0.82 * AW metal - 0.10*X) , wherein AW metal is the atomic weight of the metal and X is the metal valence.
  • the obtained calcined material is utilized as a component in an electrode for a battery, when a battery is manufactured, said battery comprising at least one electrochemical cell, and wherein the at least one electrochemical cell comprises at least two electrodes 1,2 and at least one electrolyte 7, wherein at least one of the electrodes 1,2 comprises a) the obtained calcined material, b) at least one conducting material, and c) at least one binder .
  • a component material of a battery electrode comprising TiO 2 , wherein the TiO 2 ( cBo)mprises a fraction of TiO 2 (B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AW metal - 0.10*X) ⁇ R ⁇ ( 0.82 *AW metal - 0.10*X) , wherein AW metal is the atomic weight of the metal and X is the metal valence.
  • fraction means that a part of the TiO 2 is in bronze form, i.e. TiO 2 (B) .
  • the second aspect can be expressed also in Ti/metal ratio (R) in the component material.
  • This ratio R can be calculated from the content of metal ions.
  • the metal ions will be present as a metal oxide in the material.
  • a general formula for the said metal stabilised material is :
  • R is a real number > 0 and interpreted as the Ti/metal ratio ;
  • MO 2/X is a metal oxide
  • X is the metal valence
  • M wt% 100* (AW metal / (AW metal + R*AW Ti + (2R+X/2) *AW O ) (2) where ,
  • AW metal the atomic weight of the metal
  • AW Ti the atomic weight of titanium
  • AW o the atomic weight of oxygen.
  • the Ti to metal ratio, R can then be solved in terms of weight percent metal.
  • R ⁇ AW metal * [ (100/M wt% ) -1] - (X / 2 ) * AW o ⁇ / MW TiO2 (3)
  • AWmetai the atomic weight of the metal
  • X is the metal valence
  • AW O the atomic weight of oxygen
  • TiO2 the molecular weight of TiO 2 .
  • AW metal is the atomic weight of the metal and X is the metal valence.
  • a component material of a battery electrode comprising TiCA wherein the TiO 2 comprises a fraction of TiO 2 (B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AW metal - 0.10*X) ⁇ R ⁇ ( 0.82*AW metal - 0.10*X) , wherein AW metal is the atomic weight of the metal and X is the metal valence .
  • the ratio R is preserved after calcination and is the same in the finished product.
  • TiO 2 (B) bronze based Li-ion battery anodes Usually the metal ions which are added according to the present invention are considered very detrimental in TiO 2 (B) bronze based Li-ion battery anodes, because small amounts of metals decrease performance dramatically in terms of lithium capacity. The metals take up space where lithium would normally fit.
  • Most publications concerning TiO 2 (B) in Li-ion batteries go to great lengths to obtain the least metal as possible to maximize lithium capacity .
  • TiO 2 (B) appears to be unstable when prepared according to some methods according to prior art, in particular this is true of inexpensive methods. Such methods typically involve low temperature and pressure relative to other methods in the prior art with higher temperature and pressure. They can be referred to as low temperature and pressure pathways - or LTP pathways.
  • the range of metal ion content is in the alternative wording of the second aspect formulated as Ti:metal ratio R, not in wt%, but instead based on the number of atoms of Ti to the number of atoms of metal.
  • the Ti:metal atomic ratio R in the final product is greater than 4: 1 Ti:metal (Giving about 20% loss of theoretical lithium capacity) .
  • the final product is for this calculation considered to be the material comprising TiO 2 .
  • the Ti:metal atomic ratio R in the material is greater than 4: 1 Ti:metal, wherein the metal is present as ions, with the proviso that Ti, Ta and Nb are not included as metal.
  • Nb and Ta are atoms of Ti (and Ta and Nb) in the atomic ratio R.
  • metal denotes stabilizing metals. If only a very small fraction of Nb is present, its contribution to the ratio R is negligible. Thus for small amounts of Nb and/or Ta, such as a few percent (or 0.5-1 wt%) its contribution can be essentially ignored since the effect is small. At larger amounts of either Nb or Ta, their differing valence compared to Ti must be accounted for - see equation 4.
  • Niobium doping of TiO 2 bronze can be advantageous in increasing the electrical conductivity of the said bronze material during the cycling of a lithium ion battery and can increase the lithium ion capacity of the resulting electrode constructed from the bronze due to its slightly larger radius. Nb doping can even have a positive impact on the conductivity at relatively low amounts of niobium, this low amount being an advantage over higher amounts since niobium is relatively more expensive than titanium and it is also significantly heavier. Niobium doping can be achieved by addition of appropriate precursor compounds along with the titania precursor compounds normally used to make titania bronze. According to Xu et al.
  • niobium doping is generally limited to less than about 10%, however higher amounts can be achieved by a solvothermal process.
  • metal stabilization of niobium doped TiO 2 bronzes we are here limited, as we are for pure TiO 2 bronzes, to approaches whereby metal cations can be incorporated into an intermediate or precursor structure of TiO 2 bronze since once the bronze is formed it is difficult to incorporate the stabilizer metal ions into the TiO 2 bronze.
  • Such intermediates include but are not limited to various mixtures of H 2 Ti 3 O 7 , H 2 Ti 4 O 9 , H 2 Ti5O 11 and their hydrates and Na 2 Ti 3 O 7 , Na 2 Ti 4 O 9 , Na 2 Ti 5 O 11 and their hydrates.
  • the replacement of a part of the Ti with Nb during the manufacturing process lessens the need to add the stabilizing metal ions during the process.
  • composition of metal stabilized niobium doped titanium dioxide can usefully be described as having a general formula similar to the general formula (1) above for said metal stabilized titanium dioxide material, but now with an added Nb 2 O 5 component, where Nb 2 O 5 can also be expressed as NbO 2.5 .
  • R is a real number > 0 and interpreted as the Ti/metal ratio ;
  • S is a real number > 0 and interpreted as the Ti/Nb ratio ;
  • MO 2/X is a metal oxide
  • X is the metal valence. From this formula, and knowing the atomic weights of the elements we can easily interconvert between atomic % and weight % as we did for metal doped titania in equation (2) . Then a number of possible conversions can be done.
  • the weight % , M wt % of the stabilizing metal in a niobium doped material is:
  • M wt % 100* (AW metal / (AW metal + R*AW TI + S * R* AW Nb + ( 2.5 S R+ 2 R+X / 2 ) * AW o ) ) (5) where ,
  • AW metal the atomic weight of the metal
  • AW Ti the atomic weight of titanium
  • AW Ti the atomic weight of niobium
  • AW o the atomic weight of oxygen.
  • the Ti/M ratio for niobium doped TiO 2 , R can then be solved in terms of wt % stabilizing metal for a given Ti /Nb ratio , S .
  • R ⁇ AW metal * [ ( 100 /M wt% ) - 1 ] - (X/2) * AW o ⁇ / (MW TiO2 + S/2*MW Nb205 )
  • the Ti:metal atomic ratio R in the final product is greater than 5:1 Ti:metal (Giving about 16.7% loss in theoretical lithium capacity) .
  • the Ti:metal atomic ratio R in the final product is greater than 7: 1 (Giving about 12.5 % loss in theoretical lithium capacity) .
  • the Ti:metal atomic ratio R in the final product is greater than 9: 1 (Giving about 10% loss in theoretical lithium capacity)
  • the weight % of metal would vary a lot if it is calculated as a weight % of the final product depending on which metal is used.
  • the atomic ratio R can be readily determined by skilled persons using standard chemical analyses of materials and allows the ranges given above to be independent of the type of metal.
  • the wt% can be calculated as a function of atomic ratio, R assuming the formula (TiO 2 ) R .Na 2 O from equation (1) if the metal is sodium. See Figure 8.
  • standard dopants such as niobium are in one embodiment neglected if their amount is small compared to the amount of Ti. Up to a total amount of a few percent (3- 4 wt%) their contribution can in one embodiment be neglected for the calculation of the atomic ratio R. For a more accurate result, all standard dopants such as niobium are taken into account. Apart from Nb, at least one of Ta, W, Zr, Mo, Fe, V, In and Sn can be used as a dopant, substituting for Ti in the bronze or metal titanate or hydrogen titanate precursor Ti-0 framework.
  • Nb can be incorporated in the process using NbCl 5 , Nb 2 O 5 or KNbO 3 .
  • Niobium may significantly improve the results of these metal-stabilised bronzes.
  • Niobium substitutes for Ti in the bronze structure.
  • the material comprises Nb ions so that the Ti:Nb ratio is 8: 1 or lower.
  • the material comprises Nb in an amount in the range 0.1 - 20 wt% .
  • the material comprises Nb in an amount in the range 0 - 20 wt%.
  • the amount of Nb is even higher so that the ratio Ti:Nb is lower than 8.
  • the amount of Nb or other dopant is calculated based on the finished material, or on the precursor hydrogen or metal titanate since the Ti:Nb (or Ti : dopant ) ratio of the bronze framework is the same as in its precursors.
  • FIG 8 there is a graph showing weight % of stabilizing metal versus Ti/M atomic ratio. It is easy to see that for an equivalent atomic ratio, a stabilizing metal represents a greater fraction of the weight if it is a heavier metal.
  • the metal ions are at least one type of ion of a metal selected from rare earth elements.
  • the metal ions are at least one type of ion of a metal selected from transition metals, which have the ability to form cations with an incomplete d sub-shell.
  • transition metals follow the IUPAC definition that there is an incomplete d sub-shell.
  • the metal ions are at least one type of ion of a metal selected from alkaline earth metals and transition metals.
  • the metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium, caesium, zinc, and lanthanum. In one embodiment, the metal ions are at least one type of ion of a metal selected from the group consisting of indium, tin, lead, and bismuth. In one embodiment complex ions such as charged clusters comprising more than one atom can be the stabilizing ion provided it can substitute for Na ions between the TiO 2 sheets in the layered Na 2 Ti n O 2n+1 layered sodium titanate phase from aqueous solution.
  • a BSI value is above 0.8 for the TiO 2 , wherein the BSI value is calculated from laser Raman spectroscopy of the TiO 2 , according to the following method: the instrument is calibrated against a silicon wafer standard, the intensity for the bronze B g ( 2 ) peak located in the interval 190 - 205 cm -1 minus the background intensity is divided by the intensity for the E g ( 1 ) anatase peak located in the interval 140 - 160 cm -1 minus the background intensity and then the resulting ratio is divided with a normalization factor which is calculated as the intensity of the E g ( 1 ) anatase peak minus the background intensity divided by the intensity for the bronze B g (2) peak minus the background intensity for pure TiO 2 (B) , wherein the background intensity is calculated as the average intensity in the region with a wavenumber higher than the zero-peak and lower than the intensity originating from the sample.
  • the anatase Eg ( 1 ) and bronze B g (2) peaks used in the BSI may be at slightly different wavenumbers for different materials and peaks in the given intervals should be used since the peaks are expected to be within the intervals. That is the B g ( 2 ) peak position for a pure bronze near 200c m -1 should be determined as should that of the E g ( 1 ) peak near 150 cm -1 of anatase made by destabilizing the bronze by heating to 600 °C for 2 hours.
  • a pure bronze is found to have a moderate to strong B g (2) peak at 202 cm -1 and when heated to 600 °C for 2 hours, has a strong anatase E g ( 1 ) peak at 148 cm -1 .
  • E g ( 1 ) peak should be the positions used to determine the peak intensities for the BSI calculation.
  • the position at which the background intensity is calculated may vary depending on the optical configuration of the Raman spectrometer. Importantly this value be taken at a position where the trace of the spectrum is flat or nearly flat in the range from just above 0 cm -1 to where the spectrometer starts to have a response from the sample in question.
  • the metal ions are of at least one type of ion selected from the group consisting of sodium, potassium, rubidium, caesium, zinc and lanthanum. In one embodiment of the second aspect, the metal ions are of at least one type of ion selected from the group consisting of sodium, and potassium. In one embodiment of the second aspect the metal ions are ions of sodium. In one embodiment of the second aspect the metal ions are ions of potassium. In addition to the metal ions mentioned above, the material may comprise further ions. In one embodiment of the second aspect, the material comprises at least one type of ion selected from the group consisting of calcium, magnesium, strontium and barium.
  • the material comprises at least one type of ion selected from the group consisting of silver, copper, and cadmium. In one embodiment of the second aspect, the material comprises at least one type of ion selected from the rare earth metals .
  • the BET specific surface area according to ISO 9277 of the TiO 2 is in the range 2-30 m 2 /g. In one embodiment of the second aspect, the BET specific surface area according to ISO 9277 of the TiO 2 is in the range 30-50 m 2 /g. In one embodiment of the second aspect, the BET specific surface area according to ISO 9277 of the TiO 2 is in the range 50- 100 m 2 /g. In one embodiment of the second aspect, the BET specific surface area according to ISO 9277 of the TiO 2 is in the range 100-200 m 2 /g.
  • the TiO 2 comprises 1.5 to 6 wt% of metal ions, calculated by weight of the material. Using the above formula this can be expressed as
  • the TiO 2 constitutes 70-90 wt% of the electrode material.
  • a battery comprising at least one electrochemical cell, said at least one electrochemical cell comprises at least two electrodes 1,2 and at least one electrolyte 7, wherein at least one of the electrodes 1,2 comprises a) a material comprising TiCd, wherein the TiO 2 comprises a fraction of TiO 2 (B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, b) at least one conducting material, and c) at least one binder, wherein for the material the Ti to metal ion atomic ratio R fulfils the following condition (0.029*AWmetal - 0.10*X) ⁇ R ⁇ ( 0.82 *AWmetal - 0.10*X) , wherein AW metal is the atomic weight of the metal and X is the metal valence.
  • the metal ions are at least one type of ion of a metal selected from rare earth elements.
  • the metal ions are at least one type of ion of a metal selected from transition metals, which have the ability to form cations with an incomplete d sub-shell.
  • transition metals follow the IUPAC definition that there is an incomplete d sub-shell.
  • the metal ions are at least one type of ion of a metal selected from alkaline earth metals and transition metals.
  • the metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium, caesium, zinc and lanthanum. In one embodiment of the third aspect, the metal ions are at least one type of ion of a metal selected from the group consisting of indium, tin, lead, and bismuth.
  • the Ti:metal atomic ratio R in the material is greater than 4:1 Ti:metal, wherein the metal is present as ions.
  • the metal ions are of at least one type of ion selected from the group consisting of sodium, potassium, rubidium, caesium, zinc and lanthanum. In one embodiment of the third aspect, the metal ions are of at least one type of ion selected from the group consisting of sodium, potassium. In one embodiment of the third aspect, the metal ions comprise Nb ions. In one embodiment of the third aspect, the material comprises at least one type of ion selected from the group consisting of calcium, magnesium, strontium and barium. In one embodiment of the third aspect, the material comprises at least one type of ion selected from the group consisting of silver, copper, and cadmium. In one embodiment of the third aspect, the material comprises at least one ion selected from the group of rare earth metals, including yttrium and scandium .
  • the BET specific surface area according to ISO 9277 of the TiO 2 is in the range 2-30 m 2 /g. In one embodiment of the third aspect, the BET specific surface area according to ISO 9277 of the TiO 2 is in the range 30-50 m 2 /g. In one embodiment of the third aspect, the BET specific surface area according to ISO 9277 of the TiO 2 is in the range 50- 100 m 2 /g. In one embodiment of the third aspect, the BET specific surface area according to ISO 9277 of the TiO 2 is in the range 100-200 m 2 /g.
  • the TiO 2 comprises 1.5 to 6 wt% of metal ions, calculated by weight of the TiO 2 - Using the above formula this particular amount of metal ions in TiO 2 can be expressed as:
  • the conducting material is carbon black. In another embodiment of the third aspect, the conducting material is graphene. In yet another embodiment of the third aspect, the conducting material is conductive carbon nanotubes.
  • the TiO 2 constitutes 70-90 wt% of the electrode material.
  • the wt% ratio between the conducting material and the binder is in the range 1:1 to 7:3.
  • the battery is comprised in a vehicle or machine.
  • the battery is mounted in a vehicle.
  • the short charging time of the battery is suitable for vehicles.
  • examples of the vehicle include but are not limited to vehicles selectively chosen from the group consisting of cars, motorcycles, busses, bikes, ferries, boats, trains, tractors, cranes, fork-lifts, drilling vehicles, hoists, trams, trolleys, fork-lifts, loaders, bulldozers, excavators, graders, scrapers, boring machines and trenchers.
  • the battery comprises a working anode 1, a counter electrode 2, a separator 3, a lower casing 4, an upper casing 5, and a gasket 6.
  • the working anode 1 comprises an electrode material made by the method according to the invention.
  • the casing 4,5 encloses the electrolyte 7.
  • the battery is comprised in a consumer electronic device.
  • consumer electronic devices include but are not limited to digital telephones, laptops, pads and tablets, digital audio devices and headphones, portable speakers and amplifiers, cameras, radio devices, displays and screens, vacuum cleaners, power blocks, lighting devices, wearable devices, drones and radio-controlled devices .
  • the battery is comprised in a portable power tool.
  • portable power tools include but are not limited to drills, drivers, circular saws, reciprocating saws, jigsaws, band saws, miter saws, power hammers, sanders, grinders, routers, LED lighting, power packs, vacuum devices, soldering units, power wrenches and ratchets, multi-tools, cordless fans and blowers, trimmers, mowers, snow shovels, chain saws, polishers and buffers.
  • battery is comprised in an energy storage device.
  • the energy storage device is selectively comprised of one or more items in the group consisting of modules, packs, racks, containers, computer controllers, thermal management systems, mechanical stabilizers, shock absorbers, frames, bus bars, fire protection and thermal runaway systems, filters and gas detectors.
  • the energy storage device is comprised in one or more of the systems related to - solar energy storage, wind energy storage, hydroelectric energy, wave energy, municipal storage, industrial plant energy storage, household energy storage, recovered energy storage, energy utility provider storage.
  • a battery electrode comprising a mixture of at least one conducting material, at least one binder and a component material according to the second aspect.
  • the mixture is in a slurry state prior to its setting and forming of the electrode.
  • a method for manufacturing a TiO2 (B) , titanium dioxide bronze material for a battery electrode material comprising the steps of: a) providing an aqueous solution comprising T10C12, HC1 , and an alpha-hydroxy acid, b) increasing the pH of the solution until a precipitate is obtained, wherein the temperature is above 0 °C and below 55 °C, and c) calcining the obtained precipitate during a time range of 5 minutes to 48 hours at a temperature in the interval 300-450 °C to obtain a calcined material comprising the titanium dioxide bronze material.
  • aqueous solution comprising T10C12 is provided by dissolving at least one titanic acid with the general formula TiO x (OH) 4-2X , wherein x is 0 or 1 , in an aqueous solution comprising at least one compound selected from the group consisting of TiOCl 2 , TiCl 4 , and HCl so that a clear solution is obtained, while keeping the temperature below 30 °C.
  • A5 The method according to any one of embodiments Al- A4 , wherein the obtained precipitate is washed in water between steps b) and c) .
  • A6 The method according to any one of embodiments Al- A5 , wherein the method is carried out at a pressure p being ambient pressure ⁇ 20%.
  • step b) The method according to any one of embodiments Al - A14, wherein the pH in step b) is increased also after the precipitate is obtained and wherein the pH is increased to a value in the range 7-10.
  • A17 The method according to any one of embodiments Al - Al 6 , wherein at least one conducting material and least one binder is added to the calcined material to obtain an electrode material for a battery .
  • a BET specific surface area of the calcined material according to ISA 9277 is in the range of 2-30 m 2 / g .
  • A25 The electrode material according to any one of embodiments A23-A24 , wherein wt% ratio between the conducting material and the binder is in the range 1 :1 to 7:3.
  • A26 The electrode material according to any one of embodiments A23-A25 , wherein the conducting material is carbon black.
  • A27 The electrode material according to any one of embodiments A23-A26, wherein the titanium dioxide bronze comprises at least one type metal ion of selected from m metal group of sodium, potassium, rubidium, caesium, rubidium, zinc, lanthanum, and tin.
  • a method for inhibiting the formation of anatase during manufacture of a material comprising TiO 2 (B) , titanium dioxide bronze comprising the steps of: a) providing an aqueous mixture comprising a titanium dioxide bronze precursor with the general formula A 2 Ti n O 2n+1 .mH 2 O, and an anatase precursor, wherein A is hydrogen or a metal in cationic form, n is an integer from 3 to 6, m is a number from 0 to 2.5, wherein the content of metal ions is in the range 1.5 to 30 wt%, wherein the metal ions are at least one type of ions of a metal selected from the group consisting of sodium, potassium, rubidium, caesium, rubidium, zinc, lanthanum, and tin, and b) treating the mixture during a time range of
  • step b is in the interval 300-500 °C and content of metal ions is in the range 1.5 - 30 wt%.
  • aqueous solution comprising T10C12 is provided by dissolving at least one titanic acid with the general formula TiO x (OH) 4-2x , wherein x is 0 or 1 , in an aqueous solution comprising at least one compound selected from the group consisting of T10C12, TiCl 4 , and HC1 so that a clear solution is obtained, while keeping the temperature below 30 °C,
  • BIO The method according to any one of embodiments BIBO, wherein the method is carried out at a pressure p being ambient pressure ⁇ 20%.
  • metal ions are at least one type of ions of a metal selected from the group consisting of sodium, potassium, zinc, caesium , lithium and lanthanum.
  • B20 The battery according to embodiment B20, wherein the BET specific surface area according to ISO 9277 of the calcined material is in the range 2-30 m 2 / g . B21.
  • titanium dioxide bronze comprises at least one type metal ion of selected from the group consisting of ions of sodium, potassium, rubidium, caesium, rubidium, zinc, lanthanum, and tin.
  • a component material of a battery electrode comprising TiO 2 , wherein the TiO 2 comprises a fraction of TiO 2 (B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition ( 0. 029*AW metal - 0.10*X) ⁇ R ⁇ ( ( 0.82 *AW metal ⁇ 0.10 *X) , wherein AW metal is the atom! c weight of the metal and X is the metal valence.
  • the metal ions are at least one type of ion of a metal selected from rare earth elements .
  • metal ions are at least one type of ion of a metal selected from transition metals, which can give rise to cations with an incomplete d sub-shell .
  • metal ions are at least one type of ion of a metal selected from alkaline earth metals.
  • metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium , caesium , zinc and lanthanum .
  • metal ions are at least one type of ion of a metal selected from the group consisting of indium, tin, lead, and bismuth.
  • C13 The material according to any one of embodiments C1-C12, wherein the material comprises at least one type of ion selected from the group consisting of silver, copper, and cadmium.
  • C14 The material according to any one of embodiments C1-C13, wherein the material comprises at least one rare earth metal .
  • a battery comprising at least one electrochemical cell, said at least one electrochemical cell comprises at least two electrodes 1,2 and at least one electrolyte 7, wherein at least one of the electrodes 1,2 comprises a) a material comprising TiO 2 , wherein the TiO 2 comprises a fraction of TiO 2 (B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, b) at least one conducting material , and c) at least one binder, wherein for the material the Ti to metal ion atomic ratio R fulfils the following condition (0. 029*AW metal ⁇ 0.10*X) ⁇ R ⁇ ( 0. 82 *AW metal ⁇ 0.10*X) , wherein AW metal is the atomic weight of the metal and X is the metal valence .
  • metal ions are at least one type of ion of a metal selected from alkaline earth metals.
  • metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium , caesium , zinc and lanthanum .
  • metal ions are at least one type of ion of a metal selected from the group consisting of indium, tin, lead, and bismuth.
  • C31 The battery according to any one of embodiments C18-C30 , wherein the material comprises at least one rare earth metal .
  • C32 The battery according to any one of embodiments Cl 8-C31 , wherein the BET specific surface area according to ISO 9277 of the TiO 2 is in the range 2-30 m 2 /g.
  • An acidic, 10 wt% TiO 2 dispersion of pH ⁇ 1 was prepared by mixing 2.5 parts of titanic acid suspended in water with 1 part of TiOCl 2 solution (22-24 wt % TiO 2 , density 1.5-1. 6 g.cm -3 ) to obtain a clear solution and adding citric acid as stabilizer in mass ratio of 10: 1 TiO 2 :citric acid prior to raising the temperature to 80 °C and holding for 75 minutes and subsequent rapid cooling.
  • the said titanic acid suspended in water was pH 5.5 and was prepared by mixing 2 parts of said TiOCl 2 solution with 1 part of water and 8.8 parts 10% NaOH, keeping the temperature in the range 25-40 °C.
  • the ratio of two masses i.e., the mass of Ti in the aqueous TiOCl 2 solution used to prepare the titanic acid suspended in water and the mass of Ti in the aqueous solution of TiOCl 2 that was mixed with titanic acid to form a clear solution was 3:7.
  • the ion and water content were adjusted to pH 1 to 1.5 and 20 wt% TiCd so that an acidic sol of TiO 2 was obtained.
  • the acidic sol of TiO 2 was adjusted to 37 wt% to arrive at a 37 wt% dispersion of particles. An amount corresponding to 5.2773 g TiO 2 was taken.
  • the mixture stirred for 1 hour using a magnetic stirrer. Subsequently the mixture was divided evenly between 4 Teflon® (polytetraf louroethene ) lined autoclaves and then heated for 56 hours at 145 °C with no stirring.
  • Teflon® polytetraf louroethene
  • the air-dried powders were then stirred in solutions of 0.001, 0.005, 0.01 and 0.05 M NaOH to exchange the hydrogen for sodium.
  • the amount of solution was controlled so that the calculated amount of sodium, when fully exchanged would yield the following sodium contents of the exchanged titanates: 0.001 M - 1.6%; 0.005 M - 2.7%; 0.01 M - 6.0%; and 0.05 M - 26.9%.
  • the four samples exchanged at these four different concentrations plus the unexchanged titanate were then divided and heated to different temperatures up to 500 °C. After heating, the powders were then subject to Raman spectroscopy.
  • the samples include the sample heated to 400°C shown in Figure 1, 450°C shown in Figure 2 and the 500°C shown in Figure 3. Along with an unshown figure run at 350°C, these data from Figures 1, 2 and 3 are then used to calculate a bronze stability indicator, BSI shown in Figures 4 and 5. From these spectra, the bronze stability indicator, BSI was calculated using the following method. First, a background was subtracted from all spectra according to the average spectral intensity above the zero-peak and the first intensity from the sample.
  • This method of stabilization can be performed on small fractions of a batch of samples in order to find the BSI as a function of Na exchange and temperature. Such information will likely vary somewhat depending upon the quality and nature of the starting titanate material.
  • Each solution contained 0.35 ⁇ 0.03 g of the dry titanate, and 10 g of solution, and 10 g solution of varying metal content. Exact weights were recorded and the following weight and atomic ratios (relative to the air-dried titanate) were used.
  • the weight-% of Li relative to the airdried titanate was: 0.49, 0.91, 4.60 and 8.81 wt% respectively.
  • the Cs solution 13.8, 17.1, 48.0 and 64.9 wt% respectively.
  • For the Zn solution 4.32, 8.86, 31.88 and 48.32 wt%, respectively.
  • La solution 9.55, 16.7, 50.5 and 65.3 wt%, respectively.
  • the non-exchanged titanate was also heated in air at 350 °C for 2 hours plus 400 °C for 1 hour at the same time as the other samples.
  • Most samples displayed Raman spectra characteristic of bronze or a bronze-like phase with either zero or trace anatase when measured in multiple spots. Two exceptions were found, one being that a consistent albeit small amount of anatase was detected in the heated, non-exchanged sample.
  • the other was the Li exchanged samples. These displayed 1-5% anatase when heated to 400 °C (as judged by the size of the anatase peak near 150 cm -1 ) , although no anatase was detected in the sample exchanged in the highest concentration.
  • a stabilised bronze material was prepared by an exchange reaction similar to example 1 but now using 1 g of air dried hydrogen titanate and adding it to approximately 125g of 0.01M NaOH.
  • the sample was then washed in deionized water to remove excess ions and subsequently air dried.
  • the material was used in an electrode of a coin cell and its electrochemical properties were measured.
  • a dispersion was made with the material as follows:
  • Kynar® PVDF polyvinylidene fluoride
  • the carbon black was dispersed in a 5 wt% PVDF solution for 10 min. Afterwards the active material and additional NMP was added and the slurry was homogenised for 30 min.
  • the slurries were coated using a K control coater with a meter bar designed to leave a wet film deposit of 100 pm .
  • the electrode sheets were dried at 60 °C, roll pressed and dried again at 100 °C under vacuum for 10 hours. 12 mm 0 electrodes were punched and transferred to an Ar filled glovebox.
  • EC/DEC is Ethylene Carbonate : Diethyl Carbonate.
  • Electrochemical charge and discharge experiments were carried out on a Maccor 4200 and a LANHE CT2001A in a voltage window of 1-2.5 V vs. Li/Li+. 1C was defined as 330 mA/ g (TiO 2 ) .
  • Niobium doped TiO 2 (B) was prepared with a composition identical to Example 1, except with the addition of 0.5g Nb2O 5 stirred into the 37% TiO 2 dispersion until well homogenised, prior to addition of 10 M KOH. The sample was divided equally into four 30 ml Teflon- lined steel autoclaves and heated at 145 °C for 44.5 hours. The sample was acid exchanged by repeated centrifugation, decantation and re- suspens ion in distilled water.
  • a niobium-doped bronze material was obtained by heating 2.065 g of the washed and dried acid exchanged material from example 4. The sample was calcined by heating at 140 °C for 20 minutes, 225 °C for 1 hours, 350 °C for 30 minutes and 450 °C for one hour in air. The cooled sample was weighed and the weight loss during heating was 17.5%. The sample was hand ground in a mortar and pestle and subject to x-ray diffraction and Raman spectroscopy. The sample was found to be consistent with the bronze phase of TiO 2 , with no detectable anatase
  • the Ti/Nb ratio of the input mixture was determined as 17 and the measured ratio in the so-made bronze was also determined to be 17 by electron dispersive x-ray analysis on three separate areas of the sample indicating a homogeneous reaction of Ti and Nb oxides with KOH.
  • a Ti:Nb ratio of 17 is within the limitation that Nb ions are added up to a Ti:Nb ratio of 8. So the Ti/K ratio and Ti/Nb ratio is considered identical in the metal stabilised niobium-doped bronzes and the niobium doped bronze with residual potassium.
  • Example 5 Niobium doped bronze anode preparation and electrochemical characterization
  • Anodes were prepared using the niobium-doped TiO 2 bronze of example 5, calcined at a maximum temperature of 450
  • Two electrode slurries were prepared using the following : 0.7000 g of the active material component (TiO 2 ) . 0.2000g Super C65 carbon black (Imerys®)
  • a first mixture was made by combining 0.2g of carbon black dispersed in the 2.0 g of binder solution in a mixing cup using a vacuum centrifugal mixer running at 2000rpm for 10 minutes and then degassing under vacuum for 30 seconds .
  • a second mixture was obtained by adding 3.0 g of NMP solvent and 0.70g of active Nb-doped TiO 2 material to the mixing cup containing the first mixture, followed by mixing for 5 minutes at 2000 rpm followed by degassing for 30 seconds under vacuum .
  • a first mixture was made by combining 0.2g of carbon black, 0.7g of the active Nb-doped TiO2 and 3.0g NMP solvent in a stainless steel vial (10 ml) .
  • One ball (6.5g mass) was added to the stainless steel vial and the vial shaken in a Retsch MM 400 mixer mill at 25 Hz for 5 minutes.
  • a second mixture was obtained by adding 2.0g of binder solution to the first mixture contained in the stainless steel vial obtained after (i) above and the vial was shaken in a Retsch MM 400 mixer mill at 25 Hz for 10 minutes.
  • Extra NMP was added to adjust viscosity for casting in 1.5g steps, with a further 2 minutes mixing at 25Hz .
  • the freshly made slurries were coated onto 20 micron thick Al foil using a K control coater with a Zhentner applicator frame designed to leave a wet film deposit of 200 micrometers.
  • the electrode sheets were dried at 60 °C for 48 hours.
  • 14 mm 0 electrodes were punched from the dry electrode sheet and dried at 120 °C under vacuum for 14 hours in a glove box mini chamber and transferred to an Ar filled glove box.
  • a LANHE CT2001A tester was used in cycling the half cells. 1C was defined as 330 mA/ g (TiO 2 ) .
  • FIG. 12 A diagram from a test cycle for a cell made from the first slurry is shown in Figure 12.
  • FIG. 13 A diagram of the rate cycling for a cell made from the second slurry is shown in Figures 13 and 14.
  • Figure 14 is a zoomed out view of Figure 13.
  • Recovered capacity at C/2 (cycle 62) 218 mAh/g Recovered capacity at C/10 (cycle 64) : 229 mAh/g Recovered capacity at 1C (cycle 100) : 203 mAh/g Recovered capacity at 1C (cycle 264) : 195 mAh/g
  • the starting materials were a commercial TiOCl 2 solution, NaOH and citric acid and deionized water.
  • the TiOCl 2 solution was received with composition of approximately 35-26% TiOCl 2 , hydrochloric acid 22-24% and water 40-43%.
  • the measured density of the TiOCl2 solution at 20°C was 1.5605 ⁇ 0.0010 g.cm -3 .
  • 5.01g of water was added to 10.02g TiOCl 2 solution with stirring and cooling to below 25 °C to obtain a diluted TiOCl 2 solution.
  • To the diluted TiOCl 2 solution was added 43.85g of a solution comprising 10% by weight NaOH in water, with stirring and cooling to maintain a temperature below 25 °C.
  • calcined powder sample was then heated in air at 350 °C for one hour to obtain a calcined powder sample.
  • the calcined powder sample was then subject to analysis using a Raman spectrometer, yielding a spectrum indicating a high fraction of anatase.
  • the sample was then analysed by energy dispersive x-ray analysis (EDX) using a Zeiss scanning electron microscope.
  • EDX energy dispersive x-ray analysis
  • Example 1 Approximately 5 g of the washed precipitate of Example 1 was suspended in an excess of 0.1 M HC1 solution and stirred overnight to replace any Na in the titanium dioxide with H ions to obtain a suspension of acid exchanged titanium dioxide. The acid exchanged titanium dioxide was then washed by repeated centrifugation and decantation to obtain a neutral suspension of washed, acid-exchanged titanium dioxide at pH 5-6. The. The washed acid-exchanged titanium dioxide was then air dried, ground and found to have a tap density of 0.8 gcnr 3 . The sample was then heated at 350 °C for 1 hour and its phase determined as close to 100% anatase.
  • Example 6c 2.974g of powder from example lb was added to a mixture of 0. IM 37.8g NaOH and 61.3g deionized water. The mixture was magnetically stirred for 15 minutes and then transferred to an oven for 1 hour, the temperature being 40°C at the end, and without stirring. The pH after removal from the oven was near neutral. The sample was then washed by centrifugation and decantation multiple times and air dried. The sample was split into two, one was clcined at 300°C for 2 hours and the other at 350°C for 1 hour, with anatase content estimated at 5-20% for the former and 5-10% for the latter.
  • Example 7a 6.13g of water was added to 12.27g T1OCl2 solution with stirring and cooling to below 25°C to obtain a diluted TiOCl 2 solution.
  • To the diluted T1OCl2 solution was added 54.00g of a solution comprising 10% by weight NaOH in water, with stirring and cooling to maintain a temperature below 25°C. This resulted in a suspension of white titanium containing precipitate of approximately pH 5.
  • To this suspension was added 28.71 g of TiOCl 2 solution, keeping the temperature below 25°C until the solution became completely transparent.
  • 0.925g of citric acid was added under stirring until the citric acid was dissolved.
  • To this solution 102.035g of 10% NaOH solution was added resulting in a second suspension of titanium bearing precipitate at approximately pH 10.
  • the fine powdered titanium dioxide of example 2a was then subject to analysis by Raman microscopy and X-ray powder diffraction. These analyses indicated the fine powder was a titanium dioxide phase similar in structure to H-titanium dioxide or Na-titanium dioxide and free of any detectable anatase. Approximately 0.3g of the fine powder was then heated in air at 350 °C for one hour to obtain a calcined powder sample. The calcined powder sample was then subject to analysis using Raman spectroscopy and x-ray powder diffraction, yielding curves indicating up to 5-20% anatase and 80-95% bronze and minor NaCl. The sample was then analysed by energy dispersive x-ray analysis using a Zeiss SEM.
  • Ti/Na The atomic titanium to sodium ratio (Ti/Na) was found to be 2.13: 1 when subtracting away Na that was bonded to Cl in residual NaCl, here all Cl was assumed to be in NaCl, so the amount of Na subtracted from the total was equivalent to the atomic % of Cl.
  • Example 7c The calcined sample of Example 2b was washed to remove remaining soluble salt such that NaCl was not detected via XRD, and was then dried at 70 °C overnight. This sample was then analysed by Raman spectroscopy and found to have approximately 50% anatase and 50% bronze phases.
  • example 2c was made into an electrode and tested in an electrochemical half-cell.
  • the composition was applied in a slurry was 8: 1:1 act ive : carbon black:binder and the active loading of calcined material was between 2.7 and 3.2 mg cm -2 .
  • Active denotes the calcined material comprising titanium dioxide in bronze form.
  • a copper foil of the electrode used was 20 pm thick with average weight 16.1 mg cur 2 .
  • the capacity at cycle 3 was approximately 92 mAh/g at C/10 (see Figure 15) and an approximately stable capacity of 80 mAh/g and a Coulombic efficiency levelling out at 100% after about 5-10 cycles out to 250 cycles at C/2 (see Figure 16) .

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Abstract

The present invention relates to a component material of a battery electrode as well as a battery comprising the component material. The component material comprises a) TiO2 with a fraction of TiO2 (B), titanium dioxide in bronze phase, b) at least one conducting material, and c) at least one binder, wherein the TiO2 comprises metal ions, wherein the Ti to metal ion atomic ratio R fulfils the following condition (0.029*AWmetal 0.10*X) ≤ R ≤ (0.82*AWmetal 0.10*X), wherein AWmetal is the atomic weight of the metal and X is the metal valence, calculated by weight of the material, wherein the metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium, caesium zinc and lanthanum. A high fraction of TiO2 (B), titanium dioxide in bronze phase gives a battery with a desirable high capacity.

Description

AN ELECTRODE MATERIAL AND A BATTERY AS WELL AS THEIR
MANUFACTURE
Technical Field
The invention relates to a method for manufacturing a component material of a battery electrode. In addition, the component material of the battery electrode as well as a battery comprising the component material are encompassed .
Background
In the prior art there is disclosed methods of manufacturing titanate bronze precursor material, which can be used in the manufacture of a battery.
The known methods according to the prior art may require a) an expensive and complicated hydrothermal process step operating at elevated temperature, pressure and high alkalinity, with a limited scale up capacity of the pressure vessels, or b) a very high temperature process step, greater than approx. 800 °C to make a bronze precursor or c) making TiO2(B) from a titanium glycolate precursor which generally involves use of dangerous oxidizers such as hydrogen peroxide. Still there is the problem of anatase formation instead of formation of the desired bronze form of titanium dioxide.
For batteries, some polymorphs of TiO2 are more desirable whereas others are undesirable. Anatase is undesirable as it generally loses half of its capacity relative to the first few cycles, unlike bronze, which retains most of its capacity after an initial approx. 20% loss on first cycle. Thus, the bronze polymorph can more readily achieve high capacities than anatase. For the bronze polymorph, TiO2(B) the theoretical specific capacity is about 335 mAh/g when used as an electrode material in a lithium battery.
In particular, when preparing TiO2(B) with methods involving relatively low temperature and pressure, the prepared TiO2(B) appears unstable. Since methods using relatively low temperature and pressure are more economical it would be desirable to use them, had not the problems with unstable TiO2(B) existed.
In the art there is a problem how to stabilize the material to minimize the formation of anatase, keeping bronze during the manufacturing cycle, while the capacity of the material in a finished battery should not decrease too much, or should decrease as little as possible. On a more general level, a problem in the art is how to provide a more efficient method for manufacturing titanium dioxide in bronze form. On an even more general level a problem in the art is how to improve the manufacture of a material for a battery.
WO 2020/165419 as well as SE543124 disclose a method for manufacturing a structure of a titanium compound selected from the group consisting of sheets, wires and tubes .
Liu, Y. et al "Preparation of rutile Ti02 by hydrolysis of T1OC12 solution: experiment and theory" . RSC Adv. , 2016, 6, 59541-59549, discloses synthesis of rutile TiO2 in one step without crystalline-structure transformation.
Wang, Y. et al. "A novel method to synthesis titanium dioxide (B) / Anatase composite oxides by solid-state chemical reaction routes for promoting Li+ insertion" . Results in Physics. , Vol 14, 2019, 102451, discloses synthesis of a material comprising TiO2 in anatase and bronze form.
Still there is a need in the art to further improve the manufacture of materials comprising TiCi as well as the performance of batteries comprising such material.
Objects of the invention
It is an object of the present invention to alleviate at least some of the problems in the prior art and to provide a method for manufacturing a component material of a battery electrode, as well as a component material of a battery electrode, and a battery comprising the component material.
Summary
It has been discovered that it is possible to improve the manufacture of a TiCd (B) bronze material. It has been discovered that presence of certain metal ions can stabilize the material during the process and in particular stop or at least decrease the transition to the anatase phase of titanium dioxide during the manufacturing process. Anatase is less preferred compared to the bronze form. The material is treated to adjust the content of certain metal ions during the manufacturing process.
In a first aspect there is provided a method for manufacturing a component material of a battery electrode, the material comprising Tith, wherein the TiO2 comprises a fraction of TiO2(B) , titanium dioxide in bronze phase, the method comprising the steps of : a) providing an aqueous solution comprising TiOCl2, HC1, and an alpha-hydroxy acid, b) increasing the pH of the solution until a precipitate is obtained, wherein the temperature is above 0 °C and below 55 °C, and c) calcining the obtained precipitate during a time range of 5 minutes to 48 hours at a temperature in the interval 110-600 °C to obtain a calcined material comprising the titanium dioxide bronze material.
In a second aspect there is provided a component material of a battery electrode, the material comprising TiO2, (B) wherein the TiO2 c(Bo)mprises a fraction of TiO2 (B(B)) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AWmetal - 0.10*X) ≤ R ≤ (0.82*AWmetal - 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence.
In a third aspect there is provided a battery comprising at least one electrochemical cell, said at least one electrochemical cell comprises at least two electrodes 1,2 and at least one electrolyte 7, wherein at least one of the electrodes 1,2 comprises a) a material comprising TiO2, wherein the TiO2( cBo)mprises a fraction of TiO2(B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, b) at least one conducting material, and c) at least one binder, wherein for the material the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AWmetal - 0.10*X) ≤ R ≤ ( 0.82*AWmetal - 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence . An advantage is that titanium dioxide in bronze form is stabilized during the manufacturing process. The formation of anatase is suppressed and the fraction of titanium dioxide in bronze form is thereby equal to or increased relative to if the stabilizer was not used in the first place.
In particular, it is an advantage that a less expensive manufacturing method involving lower temperature and pressure can be used, while the stability issues with TiO2(B) have been overcome. The present invention provides a more cost efficient material and battery.
Another advantage is that a battery will have an improved capacity since the fraction of TiO2 (B) is high. The content of metal ions in the material stabilizes the material so that a high fraction of TiO2(B) is ensured. Further this has the potential to give a much higher charging rate compared to the batteries according to the prior art.
The long-term performance of the battery improves compared to the prior art.
Brief description of the drawings
The invention is further described by the appended drawings in which:
Figure 1 shows representative Raman spectra of hydrogen titanate powders from example 1, where hydrogen was exchanged for Na in increasingly concentrated NaOH solutions followed by filtering, drying at room temperature and heating to 400 °C in air. The peak at 'A' near 150 cm-1 in the 0 M spectrum is assigned to the anatase Eg ( 1 ) vibrational mode (Gariola et al. Physical Review B 81, 174305, 2010) . The peak at 'B' near 200 cm 1 is assigned to the Bg(2) vibrational mode of bronze (or bronze-like) phase of titanium dioxide (Ben Yahia et al. The Journal of Chemical Physics 130, 204501, 2009)
The same labelling, A and B are the same in all figures. The bronze stability indicator is plotted in later Figures at different temperatures and NaOH exchange concentrations .
Figure 2 shows representative Raman spectra of hydrogen titanate powders, from example 1 where hydrogen was exchanged for Na in increasingly concentrated NaOH solutions followed by filtering, drying at room temperature and heating to 450 °C in air.
Figure 3 shows representative Raman spectra of hydrogen titanate powders from example 1 where hydrogen was exchanged for Na in increasingly concentrated NaOH solutions followed by filtering, drying at room temperature and heating to 500 °C in air. This figure also clearly shows the amount of stabilization against the transition to anatase at 500 °C is positively correlated to the amount of Na exchanged into the titanate. This is also seen in figures 4 and 5 below.
Figure 4 shows bronze stability indicator (BSI) value as a function of increasing NaOH concentration in the exchange solution for a range of thermal treatment temperatures applied to the exchanged powders. The BSI is calculated from data from example 1. Note that as the concentration of the exchange solution goes up, the amount of sodium exchanged into the titanates also goes up since there was a complete or nearly complete exchange indicated by drop in pH after exchange (provided the titanate precursor is not saturated with Na) , independent of the starting NaOH concentration. Here the BSI clearly goes up as a function of sodium exchange into the titanate.
Figure 5 shows the same data as in Figure 4 was replotted to show BSI as a function of temperature for a range of exchange solution concentrations. Clearly, the stability of bronze or bronze-like phase is stabilized in an increasingly positive way as the amount of Na in the exchange solution was increased.
Figure 6 shows a schematic drawing of a battery comprising at least one electrochemical cell, said at least one electrochemical cell comprises two electrodes 1,2 and an electrolyte 7. The battery is according to the invention and comprises a working anode 1, a counter electrode 2, a separator 3, a lower casing 4, an upper casing 5, and a gasket 6. In this particular embodiment, the working anode 1 comprises an electrode material made by the method according to the invention. The casing 4, 5 encloses the electrolyte 7.
Figure 7 shows a flow chart of the method according to the present invention.
Figure 8 is a graph showing weight % of stabilizing metal versus Ti/M ratio.
Figure 9 shows calculated theoretical capacity versus Ti/M atomic ratio R for various stabilizing metals. Figure 10 shows the measured specific capacity vs the number of cycles for the measurement of example 3.
Figure 11 shows representative Raman spectra of niobium doped hydrogen titanate powders where where hydrogen was exchanged for Na in increasingly concentrated NaOH solutions followed by filtering, drying at room temperature and heating to 550 °C in air from example 4.
Figure 12 shows the measured specific capacity vs the number of cycles for the measurement of a half cell constructed using an electrode made from the first slurry of example 4.
Figure 13 shows the measured specific capacity vs the number of cycles for the measurement of a half cell constructed using an electrode made from the second slurry of example 4.
Figure 14 shows the measured specific capacity vs the number of cycles for the measurement of a half cell constructed using an electrode made from the second slurry of example 4.
Figure 15 shows an experimental result as described more in detail in the experimental section. Figure 15 shows the specific capacity of a battery cell comprising the electrode material manufactured according to the invention, when the battery is cycled a number of times. In figure 15 it can be seen that for a battery comprising the material made according to the invention the capacity at cycle 3 was approximately 92 mAh/g at C/10 and an approximately stable capacity of 80 mAh/g.
Figure 16 shows a result from the same cell as in figure 15. In figure 16 the specific capacity as well as the Coulombic efficiency can be seen as a function of the number of cycles of the battery. The Coulombic efficiency is the lower line. It can be seen that the Coulombic efficiency levelled out at 100% after about 5-10 cycles out to 250 cycles at C/2.
Detailed description
The following detailed description discloses by way of examples details and embodiments by which the invention may be practised.
'Bronze precursor' as used in the description and the claims denote layered titanate compounds that are precursors to bronze and have a particular structure, whereas other precursor titanate compounds may transform directly to anatase. Titanate is a titanium dioxide compound. The distinction between these precursors that lead to bronze or anatase has been discussed in detail by Feist and Davies, J. Solid State Chem. 101, 275-295
(1992) and for example by Zukalova et al. , Chem. Mater. 17, 1248-1255 (2005) , both of which are explicitly incorporated herein by reference. Feist and Davies note that layered bronze precursor titanates of formula A2TinO2n+i comprise titanate sheets that stack in an ABA sequence. Also considering the water molecules, the general formula is A2TinO2n+1·mH2O . n is an integer from 3 to 6, m is a number from 0 to 2.5. Those with an AAA sequence cannot transform to bronze. The sheets themselves comprise corrugated ribbons of edge sharing TiO6 octahedra, each ribbon is n octahedral wide and ribbons form stepped sheets by sharing corners of octahedral. The step size is defined by n. For example, Na2Ti3O7 with n=3 is a step 3 layered titanate with AAA stacking, and H2Ti3O7, K2Ti4O9, H2Ti4O9.H2O and Cs2Ti5O11 H2Ti5O11.H2O are step 3, 4 and 5 layered titanates with ABA sequence, respectively.
AAA and ABA refers to the stacking sequence of titanates as normally referred to within the scientific literature involving titanates.
When stacking of the titanate layers is of the variety ABA, calcination in the temperature range about 300-500 °C, they convert, by a multi-step mechanism, to titanium dioxide bronze, TiO2 (B(B)) . An intermediate formed at approximately 140 °C in the conversion of H2Ti3O7, is thought to be an ABA stacked (non-layered) tunnel structure with formula H2Ti6O11, and then a bronze-like structure forms on further heating to approximately 225 °C with formula H0.5Ti3O6.25, which on further heating above approximately 280 °C forms TiO2(B) . Other ABA stacked intermediates are thought to occur in the heating of step 4 and 5 layered titanates.
'Anatase precursor' as used in the description and the claims denotes anatase precursors including non-ABA stacked layered compounds of titanium oxygen and hydrogen, hydrated amorphous titanium oxides or orthorhombic lepidocrocite-like layered titanates of formula HxTi2-x [ ] x/4 O4, where [ ] represents a crystal vacancy with sheets of flat rather than corrugated TiOe octahedra. These transform directly to anatase without first converting to bronze. In the present invention it is believed that when these anatase precursors are present with bronze precursors, the transition temperature of bronze to anatase is lowered due to the nucleation of anatase from anatase precursors and subsequent destabilization of bronze by these anatase seeds, and that addition of Na or other suitable ions prevent the formation of anatase via formation of stable metal titanates directly from the anatase precursors, and that any excess Na trapped in the bronze precursors transforms to a bronze-like structure. Sodium or other stabilizing ions may not need to be added separately, they may be included as controlled residuals from incomplete ion exchange of the metal titanate precursor. Where the process comprises removal of metal ions such a removal can be incomplete and not full, so that an amount of metal ions remain in the material .
Raman spectroscopy is used as a measurement technique to study TiO2 and its different phases.
All pH values in this application are measured using reference buffer solutions for the calibration of pH measuring equipment according to ISO 23496:2019.
In a battery application where a bronze structure is required, it is desirable to use the minimum amount of stabilizing Na or other metals to just keep the anatase precursors stable as metal titanates which appear to not destabilize bronze at lower temperatures compared to if no anatase precursors were present. Once anatase forms at about 110-600 °C, or for instance 300-500 °C by heating these anatase precursors, any bronze will be converted to anatase because the anatase can act as a nucleation site and is more stable than bronze.
The 'bronze stability indicator' is calculated by dividing the intensity for the Bg(2) bronze peak located in the interval 190 - 205 cm-1 minus the background intensity by the intensity for the Eg ( 1 ) anatase peak located in the interval 140 - 160 cm-1 minus the background intensity and then the resulting ratio is divided with a normalization factor which is calculated as the intensity of the Eg ( 1 ) anatase peak minus the background intensity divided by the intensity for the Bg ( 2 ) bronze peak minus the background intensity for pure TiO2 (B) , wherein the background intensity as calculated as the average intensity in the region with a wavenumber higher than the zero-peak and lower than the intensity originating from the sample. The exact location of the Eg ( 1 ) anatase and Bg(2) bronze peaks may vary somewhat depending on the conditions. The peaks can be for instance at 201 and 148 cm-1 respectively. The skilled person can easily identify the peaks and read the intensity at the peak and use that peak intensity for the calculation. Regarding the background, it is the intensity for the background between the zero-peak and the intensity from the sample, i.e. the wave number is higher than 0 and lower than the first intensity originating from the sample. This background normally corresponds to the intensity at 75 cm-1 . A corresponding formula would be (Peak heightBg(2) - background) / ( ( Peak heightEg(1) - background) *NF) . The value is then normalized with a normalization factor NF. The normalization factor is selected so that a pure TiCd bronze phase has BSI = 1. NF = (Peak heightBg(2) ) / (Peak heightEg (i) ) , for pure bronze. For a common Raman spectrometer with a green laser a normalization factor around 1.3 can be expected. Effects such as fluorescence may complicate the calculation of the BSI, so that the measurements are suitably done without significant influence of fluorescence on the spectra.
A 'clear solution' is defined as being nearly or completely transparent to visible light with little or no detectable cloudiness or scattering of visible light by undissolved titanic acid and may be determined by shining a visible light laser through the solution until it passes straight through the solution with little to no detectable scattering of visible light from within the solution to the naked eye. Alternately, it may be detected in practise when ordinary 12 point printed text is resolved through a 10 cm path-length of the solution held in a glass pipe.
A 'ratio' is used to describe a relation between different quantities. A ratio between a and b is expressed as a:b, which is interpreted as a/b, i.e. a divided by b so that the ratio is equal to a divided by b .
'Suspension' as used throughout the description are solid particles in a liquid medium. For a suspension, the particles are at least partially so large that they settle after some time due to gravity. The solid particles in the suspension can be for instance a precipitate.
'Wt%' denotes percentage by weight. All percentages and ratios are calculated by weight unless otherwise clearly stated. For instance the ratio of Ti:metal ratio is not expressed in wt%, instead the ratio is based on the number of atoms of Ti to the number of atoms of metal. The same applies to the ratio Ti:Nb, i.e. that it is the number of atoms of Ti to the number of atoms of Nb . Mass and weight for the calculation of wt% as well as other quantities are as defined in ISO 80000-4:2019.
In the first aspect there is provided a method for manufacturing a component material of a battery electrode, the material comprising TiO2, wherein the TiO2 comprises a fraction of TiO2(B) , titanium dioxide in bronze phase, the method comprising the steps of : a) providing an aqueous solution comprising TiOCl2, HC1, and an alpha-hydroxy acid, b) increasing the pH of the solution until a precipitate is obtained, wherein the temperature is above 0 °C and below 55 °C, and c) calcining the obtained precipitate during a time range of 5 minutes to 48 hours at a temperature in the interval 110-600 °C to obtain a calcined material comprising the titanium dioxide bronze material.
In one embodiment of the first aspect, the aqueous solution comprising TiOCl2 is provided by at least partial hydrolysis of TiCl4.
In one embodiment of the first aspect, the aqueous solution comprising TiOCl2 is provided by dissolving at least one titanic acid with the general formula TiOx (OH) 4-2x, wherein x is 0 or 1, in an aqueous solution comprising at least one compound selected from the group consisting of TiOCl2, TiCl4, and HCl so that a clear solution is obtained, while keeping the temperature below 30 °C.
In one embodiment of the first aspect, the at least one titanic acid is made from TiOCl2 by addition of an aqueous solution of a base until precipitation. The latter approach has the advantage that the process is easier to control, in particular in large scale. More in particular it is possible to measure and control the acidity with high accuracy. The acidity is the ability to donate protons in an aqueous solution, i.e. the acidity is the amount of acids.
In one embodiment of the first aspect, the obtained precipitate is washed in water between steps b) and c) .
The calcination is carried out so that the organic material including the alpha-hydroxy acid is removed at least essentially removed so that the effect of any remaining organic material is negligible. Further the calcination should be carried out so that a rearrangement occurs in the material in such a way that the fraction of anatase is minimized and the fraction of titanium dioxide in bronze form is maximized. This is normally done by choosing a lower temperature in the interval 300-450 °C together with a longer calcination time, or a higher temperature in the interval 300-450 °C together with a shorter calcination time. A skilled person can in the light of the description and the appended examples choose a suitable temperature and time for the calcination. A time range for the calcination is in one embodiment 5 minutes to 48 hours.
In one embodiment of the first aspect, the method is carried out at a pressure p being ambient pressure pambient pressure ±20%. This is Construed to mean 0.8pambient pressure ≤ p ≤ 1.2 pambient pressure - Ambient pressure is in one embodiment 101325 Pa. In one embodiment of the first aspect, pH is increased in step b) by addition of NaOH.
In one embodiment of the first aspect, the at least one alpha hydroxy acid is citric acid.
In one embodiment of the first aspect, the aqueous solution provided in step a) is clear. Clear is as defined above. This has the advantage that it is ensured that any reaction giving the TiOCl2 is more complete.
In one embodiment of the first aspect, the precipitate is dried and optionally ground between steps b) and c) .
In one embodiment of the first aspect, the precipitate is dried at a temperature of between 300 and 500 °C.
In one embodiment of the first aspect, the precipitate is dried for a time period of between 1 and 2 h.
In one embodiment of the first aspect, step b) further comprises the washed precipitate being suspended in an aqueous acid solution with a pH lower than 3 and stirred to replace at least a part of the cations in the titanium dioxide with H+ ions to obtain a suspension of acid exchanged titanium dioxide. In one embodiment the stirring is carried out during 2 - 24 hours. In one embodiment the acid is a mineral acid. In one embodiment the acid is HC1. In one embodiment the concentration of the acid is 0.02 to 0.5 M.
In one embodiment of the first aspect, step b) further comprises the acid exchanged titanium dioxide being washed by repeated centrifugation and decantation. In one embodiment of the first aspect, the obtained precipitate in step b) is separated from the remaining liquid between steps b) and c) .
In one embodiment of the first aspect, no transition metal ions except titanium ions are added in step a) or b) .
In one embodiment of the first aspect, at least one type of ions selected from the group consisting of Na+, K+, Rb+ and Cs+, are added at any point before step c) . Such ions have a stabilizing effect, but too high concentration of these ions can reduce the efficiency of the material in a battery. Such ions have the effect of delaying or decreasing the transition to anatase. Lighter ions are preferred in order to make the final material more lightweight. Thus, for instance Na is preferred over Cs .
In one embodiment of the first aspect, Nb-ions are added at any point before step b) . Suitably Nb-ions could be added up to an amount corresponding to a ratio of 8: 1 calculated as the ratio between the weight of Titanium ions to Niobium ions. The Nb-ions have the advantage of improving the conductivity.
In one embodiment of the first aspect, the pH in step b) is increased also after the precipitate is obtained and wherein the pH is increased to a value in the range 7-10. This has the effect that the charge of certain groups of the titanium dioxide is reversed to become negative so that positive ions such as Na+-ions are attracted to the material .
In one embodiment of the first aspect, the calcination in step c) is carried out at a temperature in the interval 300-450 °C. The lower limit for the temperature interval is one temperature selected from the group consisting of 110 °C, 260 °C, 270 °C, 300 °C, 350 °C and 400 °C. The upper limit for the temperature interval is one temperature selected from the group consisting of 600 °C, 550 °C, 500 °C and 450 °C. Any one temperature selected from the lower limits can freely be combined with any one temperature selected from the upper limits. Thus a lower limit is selected from the above mentioned lower limits and an upper limit is selected from the above mentioned upper limits and those limits are combined to an interval.
Examples of intervals include but are not limited to: 110-600 °C, 260-500 °C, 350-450 °C, 400-450 °C, 400-600 °C, and 110-450 °C.
In one embodiment of the first aspect, the calcined material is washed to reduce the content of soluble ions and then dried.
In one embodiment of the first aspect, at least one conducting material and least one binder is added to the calcined material to obtain an electrode material for a battery .
In order to obtain an electrode material for use in a battery, in one embodiment, of the method at least one conducting material and least one binder is added to the calcined material to obtain an electrode material for a battery in and/or after step c) . In one embodiment the conducting material is carbon black. In one embodiment the electrode material comprises about 90 wt% of TiO2 bronze, 6-7 wt% carbon black and 4-3 wt% binder. In one embodiment of the first aspect, at least one precursor for a conducting material is added before the calcination to obtain an electrode material for a battery. Such a conducting material should then be able to withstand the calcination. A precursor of a conducting material shall break down to a conducting material during the calcination. In one embodiment the conducting material is added after the calcination step. In one embodiment the binder is added before the calcination step. However, as most binders would not be able to withstand the calcination and/or would be oxidized during the calcination in many cases the binder is added after the calcination. In one embodiment the calcined material is mixed with binder and conducting material after the calcination. At least one precursor for a conducting material is added before the calcination to obtain an electrode material for a battery .
In one embodiment of the first aspect, the conducting material is carbon black. In one embodiment of the first aspect, the at least one conducting material, the at least one binder and the calcined material are mixed in a slurry. In one embodiment, the slurry is an aqueous slurry and water is added. In one embodiment of the first aspect, the content of the calcined material in the electrode material is 70-90 wt%.
In a fourth aspect there is provided a slurry for making a battery electrode comprising at least one conducting material, at least one binder and a calcined material manufactured according to the method of the first aspect . In one embodiment of the first aspect, a BET specific surface area of the calcined material according to ISO 9277 is in the range of 2-30 m2/g.
In one embodiment of the first aspect, the aqueous mixture obtained in step a) comprises a titanium dioxide bronze precursor with the general formula A2TinO2n+1 • mH20, and an anatase precursor, wherein A is hydrogen or a metal in cationic form, n is an integer from 3 to 6, m is a number from 0 to 2.5, wherein the content of metal ions is in the range 1.5 to 30 wt%, wherein the metal ions are at least one type of ions of a metal selected from the group consisting of sodium, potassium, rubidium, caesium, rubidium, zinc, lanthanum, and tin.
In one embodiment of the first aspect, the aqueous mixture obtained in step a) comprises a titanium dioxide bronze precursor with the general formula A2TinO2n+1 • mH20, and an anatase precursor, wherein A is hydrogen or a metal in cationic form, n is an integer from 3 to 6, m is a number from 0 to 2.5, wherein the content of metal ions is in the range 1.5 to 30 wt%, wherein the metal ions are at least one type of ions of a metal selected from the group consisting ofrare earth metals, alkaline earth metals, transition metals, sodium, potassium, rubidium, caesium, zinc, lanthanum, indium, tin, lead, bismuth, calcium, magnesium, titanium, niobium, rubidium, lithium, silver, copper, and cadmium.
In one embodiment of the first aspect, the temperature in step c) is in the interval 300-500 °C and content of metal ions is in the range 1.5 - 30 wt% . In one embodiment of the first aspect, the temperature in step c) is in the interval 300-400 °C and content of metal ions is in the range 1.5 - 6 wt%.
In one embodiment of the first aspect, the content of metal ions is adjusted to the desired value by ion exchange .
In one embodiment of the first aspect, the content of metal ions is adjusted by additions of the desired metal ions during the manufacture of the aqueous mixture.
In one embodiment of the first aspect, the manufactured component material of the battery electrode, comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition (0.029*AWmetal - 0.10*X) ≤ R ≤ ( 0.82 * AWmetal - 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence.
In one embodiment of the first aspect, the obtained calcined material is utilized as a component in an electrode for a battery, when a battery is manufactured, said battery comprising at least one electrochemical cell, and wherein the at least one electrochemical cell comprises at least two electrodes 1,2 and at least one electrolyte 7, wherein at least one of the electrodes 1,2 comprises a) the obtained calcined material, b) at least one conducting material, and c) at least one binder .
In the second aspect there is provided a component material of a battery electrode, the material comprising TiO2, wherein the TiO2( cBo)mprises a fraction of TiO2(B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AWmetal - 0.10*X) ≤ R ≤ ( 0.82 *AWmetal - 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence.
The word "fraction" means that a part of the TiO2 is in bronze form, i.e. TiO2 (B) .
The second aspect can be expressed also in Ti/metal ratio (R) in the component material. This ratio R can be calculated from the content of metal ions. The metal ions will be present as a metal oxide in the material. A general formula for the said metal stabilised material is :
( TiO2 ) R·MO2/X (1) where ,
R is a real number > 0 and interpreted as the Ti/metal ratio ;
MO2/X is a metal oxide, and
X is the metal valence.
For example, if the metal is Na with a valence of x=l, and the Ti/Na ratio, R = 2, then the chemical formula of the stabilized material is:
(TiO2) 2 ® NaOi/2
If La with a valence of x=3 is the metal, the chemical formula then the stabilized material is:
( TiO2 ) 2 • LaO3/2 In any case the weight percent, Mwt% of the metal in the material i s :
Mwt% = 100* (AWmetal/ (AWmetal + R*AWTi + (2R+X/2) *AWO ) (2) where ,
AWmetal = the atomic weight of the metal
AWTi = the atomic weight of titanium
AWo = the atomic weight of oxygen.
The Ti to metal ratio, R can then be solved in terms of weight percent metal.
The expression for R is as follows:
R = {AWmetal* [ (100/Mwt%) -1] - (X / 2 ) * AWo }/ MWTiO2 (3) where ,
AWmetai = the atomic weight of the metal
Mwt% of the metal in the material
X is the metal valence
AWO = the atomic weight of oxygen MWTiO2 = the molecular weight of TiO2.
When using the limits 1.5 to 30 wt% of metal ions, which can be assumed to be essentially the same as the wt% of metal in the material, then we have the following limits for the Ti to metal ratio. With an atomic weight AWo of 16 for oxygen and a molecular weight MWTiO2 of 79.87 for TiO2 the upper and lower limits become the following: Upper 1 imi t (1.5 wt % ) : { AWmetal* [ (100/1.5 ) — 1 ] - (X/2) * 16 }/79.87
Equals: 0.82*AWmetal - 0.10*X
Lower limit (30 wt%) : {AWmetai* [ (100/30) -l] - (X/2) * 16 }/79.87
Equals: 0.029*AWmetal - 0.10*X
Where AWmetal is the atomic weight of the metal and X is the metal valence.
An example for sodium is AWmetal 22.99 u, X = 1, which gives 0.571 ≤ R ≤ 18.802.
Thus with an alternative wording of the second aspect there is provided a component material of a battery electrode, the material comprising TiCA wherein the TiO2 comprises a fraction of TiO2(B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AWmetal - 0.10*X) ≤ R ≤ ( 0.82*AWmetal - 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence .
The ratio R is preserved after calcination and is the same in the finished product.
Usually the metal ions which are added according to the present invention are considered very detrimental in TiO2(B) bronze based Li-ion battery anodes, because small amounts of metals decrease performance dramatically in terms of lithium capacity. The metals take up space where lithium would normally fit. Most publications concerning TiO2(B) in Li-ion batteries go to great lengths to obtain the least metal as possible to maximize lithium capacity . TiO2(B) appears to be unstable when prepared according to some methods according to prior art, in particular this is true of inexpensive methods. Such methods typically involve low temperature and pressure relative to other methods in the prior art with higher temperature and pressure. They can be referred to as low temperature and pressure pathways - or LTP pathways.
In order to achieve bronze stability via LTP pathways, the present inventors have after extensive research discovered that if metal ions are added during an LTP pathway, there is an improved bronze yield. However, if too much is added, then the lithium capacity is reduced more than necessary. Thus there is a trade-off between on one hand improved stability of TiO2(B) during the manufacture with improved yield of TiO2(B) and on the other hand the lithium capacity in a battery with at least one electrode comprising the material with
TiO2 (B) .
The skilled person realizes this trade off and can in the light of the description select a suitable amount of added metal ions so that both the stability during manufacture and the capacity of finished battery becomes as desired.
The range of metal ion content is in the alternative wording of the second aspect formulated as Ti:metal ratio R, not in wt%, but instead based on the number of atoms of Ti to the number of atoms of metal. In one embodiment of the second aspect for the material comprising TiO2(B) , the Ti:metal atomic ratio R in the final product is greater than 4: 1 Ti:metal (Giving about 20% loss of theoretical lithium capacity) . The final product is for this calculation considered to be the material comprising TiO2. The Ti:metal atomic ratio R in the material is greater than 4: 1 Ti:metal, wherein the metal is present as ions, with the proviso that Ti, Ta and Nb are not included as metal. It is only used for the number of atoms of Ti (and Ta and Nb) in the atomic ratio R. The same applies for Nb and Ta since they can replace Ti in the TiO2 (B) structure. "metal" denotes stabilizing metals. If only a very small fraction of Nb is present, its contribution to the ratio R is negligible. Thus for small amounts of Nb and/or Ta, such as a few percent (or 0.5-1 wt%) its contribution can be essentially ignored since the effect is small. At larger amounts of either Nb or Ta, their differing valence compared to Ti must be accounted for - see equation 4.
Niobium doping of TiO2 bronze can be advantageous in increasing the electrical conductivity of the said bronze material during the cycling of a lithium ion battery and can increase the lithium ion capacity of the resulting electrode constructed from the bronze due to its slightly larger radius. Nb doping can even have a positive impact on the conductivity at relatively low amounts of niobium, this low amount being an advantage over higher amounts since niobium is relatively more expensive than titanium and it is also significantly heavier. Niobium doping can be achieved by addition of appropriate precursor compounds along with the titania precursor compounds normally used to make titania bronze. According to Xu et al. (2020) ChemElectroChem 2020, 7, 4016-4023, niobium doping is generally limited to less than about 10%, however higher amounts can be achieved by a solvothermal process. Regarding metal stabilization of niobium doped TiO2 bronzes, we are here limited, as we are for pure TiO2 bronzes, to approaches whereby metal cations can be incorporated into an intermediate or precursor structure of TiO2 bronze since once the bronze is formed it is difficult to incorporate the stabilizer metal ions into the TiO2 bronze. Such intermediates include but are not limited to various mixtures of H2Ti3O7, H2Ti4O9, H2Ti5O11 and their hydrates and Na2Ti3O7, Na2Ti4O9, Na2Ti5O11 and their hydrates.
At least under some circumstances the replacement of a part of the Ti with Nb during the manufacturing process lessens the need to add the stabilizing metal ions during the process.
The composition of metal stabilized niobium doped titanium dioxide can usefully be described as having a general formula similar to the general formula (1) above for said metal stabilized titanium dioxide material, but now with an added Nb2O5 component, where Nb2O5 can also be expressed as NbO2.5.
(NbO2.5 )R/S· ( TiO2 ) R· MO2/X, (4)
Where ,
R is a real number > 0 and interpreted as the Ti/metal ratio ;
S is a real number > 0 and interpreted as the Ti/Nb ratio ;
MO2/X is a metal oxide, and
X is the metal valence. From this formula, and knowing the atomic weights of the elements we can easily interconvert between atomic % and weight % as we did for metal doped titania in equation (2) . Then a number of possible conversions can be done.
Firstly, the weight % , Mwt% of the stabilizing metal in a niobium doped material is:
Mwt% = 100* (AWmetal/ (AWmetal + R*AWTI + S * R* AWNb + ( 2.5 S R+ 2 R+X / 2 ) * AWo ) ) (5) where ,
AWmetal = the atomic weight of the metal
AWTi = the atomic weight of titanium
AWTi = the atomic weight of niobium AWo = the atomic weight of oxygen.
In the related patent applications SE 2050954-3 and SE 2050955-0 the range of values of metal stabilization was expressed in terms of weight % metal compared to TiO2, and then we can set the value of R/S in formula (4) to be effectively zero, in which case the wt % Na relative to TiO2 for Nb doped TiO2 is found by applying formula (1) •
The Ti/M ratio for niobium doped TiO2, R can then be solved in terms of wt % stabilizing metal for a given Ti /Nb ratio , S .
R = { AWmetal* [ ( 100 /Mwt% ) - 1 ] - (X/2) * AWo }/ (MWTiO2 + S/2*MWNb205)
(6)
A similar approach can be taken for calculating equations 2 and 3 when other elements are substituted for oxygen, such as nitrogen or fluorine, or for accounting for crystal lattice vacancies.
In another embodiment of the second aspect, the Ti:metal atomic ratio R in the final product is greater than 5:1 Ti:metal (Giving about 16.7% loss in theoretical lithium capacity) .
In yet another embodiment of the second aspect, the Ti:metal atomic ratio R in the final product is greater than 7: 1 (Giving about 12.5 % loss in theoretical lithium capacity) .
In a further embodiment of the second aspect the Ti:metal atomic ratio R in the final product is greater than 9: 1 (Giving about 10% loss in theoretical lithium capacity)
It has turned out that a highly competitive material for battery electrodes can be made with very competitive Li capacity although a certain fraction of the Li capacity is lost due to the addition of metal ions.
Both one metal as well as mixtures of metals are encompassed for the addition of metal ions.
The weight % of metal would vary a lot if it is calculated as a weight % of the final product depending on which metal is used.
The atomic ratio R can be readily determined by skilled persons using standard chemical analyses of materials and allows the ranges given above to be independent of the type of metal. For metals the wt% can be calculated as a function of atomic ratio, R assuming the formula (TiO2)R.Na2O from equation (1) if the metal is sodium. See Figure 8.
For the calculation of the Ti:metal atomic ratio R standard dopants such as niobium are in one embodiment neglected if their amount is small compared to the amount of Ti. Up to a total amount of a few percent (3- 4 wt%) their contribution can in one embodiment be neglected for the calculation of the atomic ratio R. For a more accurate result, all standard dopants such as niobium are taken into account. Apart from Nb, at least one of Ta, W, Zr, Mo, Fe, V, In and Sn can be used as a dopant, substituting for Ti in the bronze or metal titanate or hydrogen titanate precursor Ti-0 framework.
Nb can be incorporated in the process using NbCl5, Nb2O5 or KNbO3. Niobium may significantly improve the results of these metal-stabilised bronzes. Niobium substitutes for Ti in the bronze structure.
In one embodiment of the second aspect the material comprises Nb ions so that the Ti:Nb ratio is 8: 1 or lower. The limit in this embodiment corresponds to a ratio (Ti/Nb) = (8/1) = 8, calculated based on the number of atoms of Ti and Nb in the finished material. In an alternative embodiment, the material comprises Nb in an amount in the range 0.1 - 20 wt% . In another alternative embodiment the material comprises Nb in an amount in the range 0 - 20 wt%. In yet another embodiment the amount of Nb is even higher so that the ratio Ti:Nb is lower than 8. The amount of Nb or other dopant is calculated based on the finished material, or on the precursor hydrogen or metal titanate since the Ti:Nb (or Ti : dopant ) ratio of the bronze framework is the same as in its precursors.
In figure 8 there is a graph showing weight % of stabilizing metal versus Ti/M atomic ratio. It is easy to see that for an equivalent atomic ratio, a stabilizing metal represents a greater fraction of the weight if it is a heavier metal.
Figure 9 shows calculated theoretical capacity versus Ti/M atomic ratio for various stabilizing metals. Lighter stabilizing metals are predicted to have less impact on the theoretical capacity at a given Ti/M ratio. In other words, if a Ti/M ratio needs be above a certain value to achieve stabilization (say at an index >0.8) , then the lighter stabilizing metals will yield higher theoretical capacities in mAh/g. Also note this diagram is applicable to all stabilizing metals since the curves are calculated from atomic weights. The curves for metals with intermediate atomic weights simply fall in between the curves shown. For example, for silver, AW = 107.9 will fall between that for Rb and Cs . For mixed metals, simply use the average (i.e. arithmetic mean) atomic weight, for example a mixture of Na and K will fall between the Na and K curves.
In one embodiment of the second aspect, the metal ions are at least one type of ion of a metal selected from rare earth elements.
Any cations can be added as metal ions, providing that the metal can substitute for Na ions between the TiO sheets in the layered Na2TinO2n+1 layered sodium titanate phase from aqueous solution. In one embodiment, the metal ions are at least one type of ion of a metal selected from transition metals, which have the ability to form cations with an incomplete d sub-shell. The definition of transition metals follow the IUPAC definition that there is an incomplete d sub-shell. In one embodiment, the metal ions are at least one type of ion of a metal selected from alkaline earth metals and transition metals. In one embodiment, the metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium, caesium, zinc, and lanthanum. In one embodiment, the metal ions are at least one type of ion of a metal selected from the group consisting of indium, tin, lead, and bismuth. In one embodiment complex ions such as charged clusters comprising more than one atom can be the stabilizing ion provided it can substitute for Na ions between the TiO2 sheets in the layered Na2TinO2n+1 layered sodium titanate phase from aqueous solution.
In one embodiment of the second aspect, a BSI value is above 0.8 for the TiO2, wherein the BSI value is calculated from laser Raman spectroscopy of the TiO2, according to the following method: the instrument is calibrated against a silicon wafer standard, the intensity for the bronze Bg ( 2 ) peak located in the interval 190 - 205 cm-1 minus the background intensity is divided by the intensity for the Eg ( 1 ) anatase peak located in the interval 140 - 160 cm-1 minus the background intensity and then the resulting ratio is divided with a normalization factor which is calculated as the intensity of the Eg ( 1 ) anatase peak minus the background intensity divided by the intensity for the bronze Bg(2) peak minus the background intensity for pure TiO2 (B) , wherein the background intensity is calculated as the average intensity in the region with a wavenumber higher than the zero-peak and lower than the intensity originating from the sample. The anatase Eg ( 1 ) and bronze Bg(2) peaks used in the BSI may be at slightly different wavenumbers for different materials and peaks in the given intervals should be used since the peaks are expected to be within the intervals. That is the B g ( 2 ) peak position for a pure bronze near 200c m-1 should be determined as should that of the Eg ( 1 ) peak near 150 cm-1 of anatase made by destabilizing the bronze by heating to 600 °C for 2 hours. For example, a pure bronze is found to have a moderate to strong Bg(2) peak at 202 cm-1 and when heated to 600 °C for 2 hours, has a strong anatase Eg ( 1 ) peak at 148 cm-1 . These should be the positions used to determine the peak intensities for the BSI calculation. Similarly, the position at which the background intensity is calculated may vary depending on the optical configuration of the Raman spectrometer. Importantly this value be taken at a position where the trace of the spectrum is flat or nearly flat in the range from just above 0 cm-1 to where the spectrometer starts to have a response from the sample in question.
In one embodiment of the second aspect, the metal ions are of at least one type of ion selected from the group consisting of sodium, potassium, rubidium, caesium, zinc and lanthanum. In one embodiment of the second aspect, the metal ions are of at least one type of ion selected from the group consisting of sodium, and potassium. In one embodiment of the second aspect the metal ions are ions of sodium. In one embodiment of the second aspect the metal ions are ions of potassium. In addition to the metal ions mentioned above, the material may comprise further ions. In one embodiment of the second aspect, the material comprises at least one type of ion selected from the group consisting of calcium, magnesium, strontium and barium. In one embodiment of the second aspect, the material comprises at least one type of ion selected from the group consisting of silver, copper, and cadmium. In one embodiment of the second aspect, the material comprises at least one type of ion selected from the rare earth metals .
In one embodiment of the second aspect, the BET specific surface area according to ISO 9277 of the TiO2 is in the range 2-30 m2/g. In one embodiment of the second aspect, the BET specific surface area according to ISO 9277 of the TiO2 is in the range 30-50 m2/g. In one embodiment of the second aspect, the BET specific surface area according to ISO 9277 of the TiO2 is in the range 50- 100 m2/g. In one embodiment of the second aspect, the BET specific surface area according to ISO 9277 of the TiO2 is in the range 100-200 m2/g.
In one embodiment of the second aspect, the TiO2 comprises 1.5 to 6 wt% of metal ions, calculated by weight of the material. Using the above formula this can be expressed as
( 0.20*AWmetal - 0.10*X) ≤ R ≤ ( 0.82*AWmetal - 0.10*X)
In one embodiment of the second aspect, the TiO2 constitutes 70-90 wt% of the electrode material. In the third aspect there is provided a battery comprising at least one electrochemical cell, said at least one electrochemical cell comprises at least two electrodes 1,2 and at least one electrolyte 7, wherein at least one of the electrodes 1,2 comprises a) a material comprising TiCd, wherein the TiO2 comprises a fraction of TiO2(B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, b) at least one conducting material, and c) at least one binder, wherein for the material the Ti to metal ion atomic ratio R fulfils the following condition (0.029*AWmetal - 0.10*X) ≤ R ≤ ( 0.82 *AWmetal - 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence.
In one embodiment of the third aspect, the metal ions are at least one type of ion of a metal selected from rare earth elements.
In one embodiment of the third aspect, the metal ions are at least one type of ion of a metal selected from transition metals, which have the ability to form cations with an incomplete d sub-shell. The definition of transition metals follow the IUPAC definition that there is an incomplete d sub-shell.
In one embodiment of the third aspect, the metal ions are at least one type of ion of a metal selected from alkaline earth metals and transition metals.
In one embodiment of the third aspect, the metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium, caesium, zinc and lanthanum. In one embodiment of the third aspect, the metal ions are at least one type of ion of a metal selected from the group consisting of indium, tin, lead, and bismuth.
In one embodiment of the third aspect, the Ti:metal atomic ratio R in the material is greater than 4:1 Ti:metal, wherein the metal is present as ions.
In one embodiment of the third aspect, the metal ions are of at least one type of ion selected from the group consisting of sodium, potassium, rubidium, caesium, zinc and lanthanum. In one embodiment of the third aspect, the metal ions are of at least one type of ion selected from the group consisting of sodium, potassium. In one embodiment of the third aspect, the metal ions comprise Nb ions. In one embodiment of the third aspect, the material comprises at least one type of ion selected from the group consisting of calcium, magnesium, strontium and barium. In one embodiment of the third aspect, the material comprises at least one type of ion selected from the group consisting of silver, copper, and cadmium. In one embodiment of the third aspect, the material comprises at least one ion selected from the group of rare earth metals, including yttrium and scandium .
In one embodiment of the third aspect, the BET specific surface area according to ISO 9277 of the TiO2 is in the range 2-30 m2/g. In one embodiment of the third aspect, the BET specific surface area according to ISO 9277 of the TiO2 is in the range 30-50 m2/g. In one embodiment of the third aspect, the BET specific surface area according to ISO 9277 of the TiO2 is in the range 50- 100 m2/g. In one embodiment of the third aspect, the BET specific surface area according to ISO 9277 of the TiO2 is in the range 100-200 m2/g.
In one embodiment of the third aspect, the TiO2 comprises 1.5 to 6 wt% of metal ions, calculated by weight of the TiO2- Using the above formula this particular amount of metal ions in TiO2 can be expressed as:
( 0.20*AWmetal - 0.10*X) ≤ R ≤ ( 0.82*AWmetal - 0.10*X) .
In one embodiment of the third aspect, the conducting material is carbon black. In another embodiment of the third aspect, the conducting material is graphene. In yet another embodiment of the third aspect, the conducting material is conductive carbon nanotubes.
In a further embodiment of the third aspect, the TiO2 constitutes 70-90 wt% of the electrode material.
In yet a further embodiment of the third aspect, the wt% ratio between the conducting material and the binder is in the range 1:1 to 7:3.
In an embodiment of the third aspect, the battery is comprised in a vehicle or machine. In such an embodiment the battery is mounted in a vehicle. The short charging time of the battery is suitable for vehicles. In the third aspect examples of the vehicle include but are not limited to vehicles selectively chosen from the group consisting of cars, motorcycles, busses, bikes, ferries, boats, trains, tractors, cranes, fork-lifts, drilling vehicles, hoists, trams, trolleys, fork-lifts, loaders, bulldozers, excavators, graders, scrapers, boring machines and trenchers. In one embodiment of the third aspect as shown in Figure 6, the battery comprises a working anode 1, a counter electrode 2, a separator 3, a lower casing 4, an upper casing 5, and a gasket 6. In this particular embodiment, the working anode 1 comprises an electrode material made by the method according to the invention. The casing 4,5 encloses the electrolyte 7.
In another embodiment, the battery is comprised in a consumer electronic device. Examples of consumer electronic devices include but are not limited to digital telephones, laptops, pads and tablets, digital audio devices and headphones, portable speakers and amplifiers, cameras, radio devices, displays and screens, vacuum cleaners, power blocks, lighting devices, wearable devices, drones and radio-controlled devices .
In another embodiment, the battery is comprised in a portable power tool. Examples of portable power tools include but are not limited to drills, drivers, circular saws, reciprocating saws, jigsaws, band saws, miter saws, power hammers, sanders, grinders, routers, LED lighting, power packs, vacuum devices, soldering units, power wrenches and ratchets, multi-tools, cordless fans and blowers, trimmers, mowers, snow shovels, chain saws, polishers and buffers.
In yet another embodiment, battery is comprised in an energy storage device. In a non-limiting example, the energy storage device is selectively comprised of one or more items in the group consisting of modules, packs, racks, containers, computer controllers, thermal management systems, mechanical stabilizers, shock absorbers, frames, bus bars, fire protection and thermal runaway systems, filters and gas detectors. In a further embodiment, the energy storage device is comprised in one or more of the systems related to - solar energy storage, wind energy storage, hydroelectric energy, wave energy, municipal storage, industrial plant energy storage, household energy storage, recovered energy storage, energy utility provider storage.
In yet another aspect there is provided a battery electrode comprising a mixture of at least one conducting material, at least one binder and a component material according to the second aspect. In one embodiment, the mixture is in a slurry state prior to its setting and forming of the electrode.
The individual embodiments of each of the different aspects are also applicable to all other aspects and can thus be freely combined unless clearly contradictory. Two or more of all embodiments can thus be freely combined with each other in any combination regardless of the aspect which they relate to. It will be appreciated that two or more of the mentioned embodiments can be combined in any combination.
Embodiments
In the following a number of alternative embodiments are presented . One or more of the following embodiments can be freely combined with any of the aspects and embodiments mentioned above as well as any of the embodiments described below. Al. A method for manufacturing a TiO2 (B) , titanium dioxide bronze material for a battery electrode material, the method comprising the steps of: a) providing an aqueous solution comprising T10C12, HC1 , and an alpha-hydroxy acid, b) increasing the pH of the solution until a precipitate is obtained, wherein the temperature is above 0 °C and below 55 °C, and c) calcining the obtained precipitate during a time range of 5 minutes to 48 hours at a temperature in the interval 300-450 °C to obtain a calcined material comprising the titanium dioxide bronze material.
A2. The method according to embodiment Al, wherein the aqueous solution comprising T10C12 is provided by at least partial hydrolysis of TiCl4.
A3. The method according to embodiment Al, wherein the aqueous solution comprising T10C12 is provided by dissolving at least one titanic acid with the general formula TiOx (OH) 4-2X , wherein x is 0 or 1 , in an aqueous solution comprising at least one compound selected from the group consisting of TiOCl2, TiCl4, and HCl so that a clear solution is obtained, while keeping the temperature below 30 °C.
A4 . The method according to embodiment A3, wherein the at least one titanic acid is made from TiOCl2 by addition of an aqueous solution of a base until precipitation .
A5 . The method according to any one of embodiments Al- A4 , wherein the obtained precipitate is washed in water between steps b) and c) . A6. The method according to any one of embodiments Al- A5 , wherein the method is carried out at a pressure p being ambient pressure ±20%.
A7. The method according to any one of embodiments Al- A6 , wherein pH is increased in step b) by addition of Na OH.
A8. The method according to any one of embodiments Al- A7 , wherein the at least one alpha hydroxy acid is citric acid.
A9. The method according to any one of embodiments Al- A8 , wherein the aqueous solution provided in step a) is clear .
A10. The method according to any one of embodiments Al- A9 , wherein the precipitate is dried and optionally ground between steps b) and c) .
All. The method according to any one of embodiments Al - Al 0 , wherein the obtained precipitate in step b) is separated from the remaining liquid between steps b) and c) .
A12. The method according to any one of embodiments Al- All wherein no transition metal ions except titanium ions are added in step a) or b) .
A13. The method according to any one of embodiments Al - A12, wherein at least one type of ions selected from the group consisting of Na + , K+ , Rb+ and Cs+, are added at any point before step c) . Al 4. The method according to any one of embodiments Al- A13, wherein Nb-ions are added at any point before step b) .
A15. The method according to any one of embodiments Al - A14, wherein the pH in step b) is increased also after the precipitate is obtained and wherein the pH is increased to a value in the range 7-10.
Al 6. The method according to any one of embodiments Al - A15, wherein the calcined material is washed to reduce the content of soluble ions and then dried.
A17. The method according to any one of embodiments Al - Al 6 , wherein at least one conducting material and least one binder is added to the calcined material to obtain an electrode material for a battery .
A18. The method according to any one of embodiments Al - A17 , wherein at least one precursor for a conducting material is added before the calcination to obtain an electrode material for a battery .
Al 9. The method according to embodiment A17 , wherein the conducting material is carbon black.
A20. The method according to embodiment A17 or Al 9 , wherein the at least one conducting material, the at least one binder and the calcined material are mixed in a slurry.
A21. The method according to any one of embodiments A17 , Al 9 or A20 , wherein the content of the calcined material in the electrode material is 70-90 wt§ .
A22 . The method according to any one of embodiments Al-
A21 , wherein a BET specific surface area of the calcined material according to ISA 9277 is in the range of 2-30 m2 / g .
A23. An electrode material for a battery manufactured according to the method of any one of method embodiments Al -A22.
A24. The electrode material according to embodiment A23, wherein the material comprises a) 70-90 wt % of calcined titanium dioxide bronze having a BET specific surface area according to ISO 9277 in the range 2-30 m2/g, and b) 30 - 10 wt% of a mixture of i) a conducting material and ii) a binder.
A25. The electrode material according to any one of embodiments A23-A24 , wherein wt% ratio between the conducting material and the binder is in the range 1 :1 to 7:3.
A26 The electrode material according to any one of embodiments A23-A25 , wherein the conducting material is carbon black.
A27 . The electrode material according to any one of embodiments A23-A26, wherein the titanium dioxide bronze comprises at least one type metal ion of selected from m metal group of sodium, potassium, rubidium, caesium, rubidium, zinc, lanthanum, and tin.
A28. A battery having an electrode comprising a titanium dioxide bronze material manufactured according to the method of any one of method embodiments A1-A22.
A29. The battery according to embodiment A28 wherein the BET specific surface area according to ISO 9277 is in the range 2-30 m2 / g . Bl. A method for inhibiting the formation of anatase during manufacture of a material comprising TiO2(B) , titanium dioxide bronze, wherein the method comprising the steps of: a) providing an aqueous mixture comprising a titanium dioxide bronze precursor with the general formula A2TinO2n+1.mH2O, and an anatase precursor, wherein A is hydrogen or a metal in cationic form, n is an integer from 3 to 6, m is a number from 0 to 2.5, wherein the content of metal ions is in the range 1.5 to 30 wt%, wherein the metal ions are at least one type of ions of a metal selected from the group consisting of sodium, potassium, rubidium, caesium, rubidium, zinc, lanthanum, and tin, and b) treating the mixture during a time range of 5 minutes to 48 hours at a temperature in the interval 300- 500 °C to obtain a calcined material comprising TiO2 (B) .
B2. The method according to embodiment Bl, wherein the temperature in step b is in the interval 300-500 °C and content of metal ions is in the range 1.5 - 30 wt%.
B3. The method according to embodiment Bl, wherein the temperature in step b is in the interval 300-400 °C and content of metal ions is in the range 1.5 - 6 wt% .
B4. The method according to any one of embodiments B1-B3, wherein the aqueous mixture is obtained by providing an aqueous solution comprising TiOCl2, and HC1 , and thereafter increasing the pH and/or the temperature of the solution until a precipitate comprising the aqueous mixture is obtained. B5. The method according to embodiment B4, wherein the aqueous solution comprising TiOCl2 is provided by at least partial hydrolysis of TiCl4.
B6. The method according to embodiment B4 , wherein the aqueous solution comprising T10C12 is provided by dissolving at least one titanic acid with the general formula TiOx (OH) 4-2x , wherein x is 0 or 1 , in an aqueous solution comprising at least one compound selected from the group consisting of T10C12, TiCl4, and HC1 so that a clear solution is obtained, while keeping the temperature below 30 °C,
BO. The method according to embodiment B6, wherein the at least one titanic acid is made from T10C12 by addition of an aqueous solution of a base until precipitation .
B8 . The method according to any one of embodiments BIBO, wherein the content of metal ions is adjusted to the desired value by ion exchange.
B9 . The method according to any one of embodiments BIBO, wherein the content of metal ions is adjusted by additions of the desired metal ions during the manufacture of the aqueous mixture.
BIO. The method according to any one of embodiments BIBO, wherein the method is carried out at a pressure p being ambient pressure ±20%.
Bll. The method according to any one of embodiments Bl- B10, wherein no transition metal ions except titanium ions are added.
B12. The method according to any one of embodiments Bl- Bll, wherein Nb-ions are added at any point. B13. The method according to any one of embodiments Bl- B12, wherein at least one conducting material and least one binder is added to the calcined material to obtain an electrode material for a battery .
B14. The method according to embodiment B13, wherein the conducting material is carbon black.
B15. The method according to embodiment B13 or B14, wherein the at least one conducting material, the at least one binder and the calcined material are mixed in a slurry.
B16. The method according to any one of embodiments B13- B15, wherein the content of the calcined material is 70- 90 wt%.
B17. The method according to any one of embodiments Bl- B16, wherein a BET specific surface area according to ISA 9277 of the calcined material is in the range of 2- 30 m2/g.
B18. The method according to any one of embodiments Bl- B17 , wherein the metal ions are at least one type of ions of a metal selected from the group consisting of sodium, potassium, zinc, caesium , lithium and lanthanum.
B19. A battery having an electrode comprising a calcined material manufactured according to any one of method embodiments B1-B19.
B20. The battery according to embodiment B20, wherein the BET specific surface area according to ISO 9277 of the calcined material is in the range 2-30 m2 / g . B21. An electrode material for a battery, wherein the material contains 70-90 wt % of calcined titanium dioxide bronze having a BET specific surface area according to ISO 9277 in the range 2-30 m2/g, manufactured according to the method of any one of method embodiments B1-B18, and 30 - 10 wt% of a mixture of a conducting material and a binder.
B22. The electrode material of embodiment B21 , wherein the wt% ratio between the conducting material and the binder is in the range 1:1 to 7:3.
B23. The electrode material of any one of embodiments B21 or B22 , wherein the conducting material is carbon black.
B24. The electrode material of any one of embodiments B21- B23 , wherein calcination temperature of the titanium dioxide bronze is in one of the ranges selected from 300- 500 °C, 300-400 °C, and 400-500 °C.
B25. The electrode material of any one of embodiments B21- B24, wherein the titanium dioxide bronze comprises at least one type metal ion of selected from the group consisting of ions of sodium, potassium, rubidium, caesium, rubidium, zinc, lanthanum, and tin.
Cl. A component material of a battery electrode, the material comprising TiO2, wherein the TiO2 comprises a fraction of TiO2 (B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition ( 0. 029*AWmetal - 0.10*X) ≤ R ≤ ( ( 0.82 *AWmetal ~ 0.10 *X) , wherein AWmetal is the atom! c weight of the metal and X is the metal valence. C2. The material according to embodiment C1, wherein the metal ions are at least one type of ion of a metal selected from rare earth elements .
C3. The material according to embodiment C1, wherein the metal ions are at least one type of ion of a metal selected from transition metals, which can give rise to cations with an incomplete d sub-shell .
C4. The material according to embodiment C1, wherein the metal ions are at least one type of ion of a metal selected from alkaline earth metals.
C5. The material according to embodiment C1, wherein the metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium , caesium , zinc and lanthanum .
C6. The material according to embodiment C1, wherein the metal ions are at least one type of ion of a metal selected from the group consisting of indium, tin, lead, and bismuth.
C7. The material according to any one of embodiments C1- C6 , wherein the Ti:metal atomic ratio R in the material is greater than 4:1.
C8. The material according to any one of embodiments C1- C7 , wherein a BSI (Bronze stability indicator) value is above 0.8 for the TiO2, wherein the BSI value is calculated from laser Raman spectroscopy of the TiO2, according to the following method: the instrument is calibrated against a silicon wafer standard, the intensity for the Bg(2) bronze peak located in the interval 190 - 205 cm-1 minus the background intensity is divided by the intensity for the Eg(l) anatase peak located in the interval 140 - 160 cm-1 minus the background intensity and then the resulting ratio is divided with a normalization factor which is calculated as the intensity of the Eg(1) anatase peak minus the background intensity divided by the intensity for the Bg(2) bronze peak minus the background intensity for pure TiO2 (B) , wherein the background intensity as calculated as the average intensity in the region with a wavenumber higher than the zero-peak and lower than the intensity originating from the sample.
C9 . The material according to any one of embodiments C1- C8 , wherein the metal ions are of at least one type of ion selected from the group consisting of sodium, and potassium.
C10. The material according to any one of embodiments C1-C9, wherein the material comprises Nb ions.
C11. The material according to any one of embodiments C1-C9, wherein the material comprises Nb ions so that the Ti:Nb ratio is 8:1 or higher.
C12. The material according to any one of embodiments C1-C11, wherein the material comprises at least one type of ion selected from the group consisting of calcium and magnesium.
C13. The material according to any one of embodiments C1-C12, wherein the material comprises at least one type of ion selected from the group consisting of silver, copper, and cadmium. C14. The material according to any one of embodiments C1-C13, wherein the material comprises at least one rare earth metal .
C15. The material according to any one of embodiments C1-C14, wherein the BET specific surface area according to ISO 9277 of the TiO2 is in the range 2-30 m2/g.
C16. The material according to any one of embodiments C1-C15, wherein R fulfils :
(0.20*AWmetal ~ 0.10*X) ≤ R ≤ (0.82*AWmetal ~ 0.10*X) .
C17 . The material according to any one of embodiments C1-C16, wherein the TiO2 constitutes 70-90 wt% of the electrode material.
CIS. A battery comprising at least one electrochemical cell, said at least one electrochemical cell comprises at least two electrodes 1,2 and at least one electrolyte 7, wherein at least one of the electrodes 1,2 comprises a) a material comprising TiO2, wherein the TiO2 comprises a fraction of TiO2 (B) , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, b) at least one conducting material , and c) at least one binder, wherein for the material the Ti to metal ion atomic ratio R fulfils the following condition (0. 029*AWmetal ~ 0.10*X) ≤ R ≤ ( 0. 82 *AWmetal ~ 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence .
C19. The battery according to embodiment C18, wherein the metal ions are at least one type of ion of a metal selected from rare earth elements . C20. The battery according to embodiment C18 , wherein the metal ions are at least one type of ion of a metal selected from transition metals, which can give rise to cations with an incomplete d sub-shell .
C21 . The battery according to embodiment C18, wherein the metal ions are at least one type of ion of a metal selected from alkaline earth metals.
C22 . The battery according to embodiment C18, wherein the metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium , caesium , zinc and lanthanum .
C23. The battery according to embodiment C18, wherein the metal ions are at least one type of ion of a metal selected from the group consisting of indium, tin, lead, and bismuth.
C24. The battery according to any one of embodiments C18-C23, wherein the Ti:metal atomic ratio R in the material is greater than 4:1 Ti:metal, wherein the metal is present as ions.
C25. The battery according to any one of embodiments C18-C24, wherein a BSI value is above 0.8 for the TiO2, wherein the BSI value is calculated from laser Raman spectroscopy of the TiO2, according to the following method: the instrument is calibrated against a silicon wafer standard, the intensity for the Bg(2) bronze peak located in the interval 190 - 205 cm-1 minus the background intensity is divided by the intensity for the E g ( 1 ) anatase peak located in the interval 140 - 160 cm- 1 minus the background intensity and then the resulting ratio is divided with a normalization factor which is calculated as the intensity of the Eg(1) anatase peak minus the background intensity divided by the intensity for the Bg(2) bronze peak minus the background intensity for pure TiO2 (B) , wherein the background intensity as calculated as the average intensity in the region with a wavenumber higher than the zero-peak and lower than the intensity originating from the sample.
C26. The battery according to any one of embodiments C18-C25 , wherein the metal ions are of at least one type of ion selected from the group consisting of sodium, potassium.
C27 . The battery according to any one of embodiments C18-C26 , wherein the material comprises Nb ions.
C28. The battery according to any one of embodiment s C18- C27 , wherein the material comprises Nb ions so that the Ti:Nb ratio is 8:1 or higher.
C29. The battery according to any one of embodiments C18-C28 , wherein the material comprises at least one type of ion selected from the group consisting of calcium and magnesium.
C30. The battery according to any one of embodiments C18-C29 , wherein the material comprises at least one type of ion selected from the group consisting of silver, copper, and cadmium.
C31. The battery according to any one of embodiments C18-C30 , wherein the material comprises at least one rare earth metal . C32 . The battery according to any one of embodiments Cl 8-C31 , wherein the BET specific surface area according to ISO 9277 of the TiO2 is in the range 2-30 m2/g.
C33. The battery according to any one of embodiment s C18- C232 , wherein R fulfils :
(0.20*AWmetal ~ 0.10*X) ≤ R ≤ (0.82*AWmetal ~ 0.10*X) .
C34. The battery according to any one of embodiments Cl 8-C33 , wherein the conducting material is carbon black .
C35. The battery according to any one of embodiment s C18- C34 , wherein the TiO2 constitutes 70-90 wt% of the electrode material.
C36. The battery according to any one of embodiments Cl 8-C35 , wherein the wt% ratio between the conducting material and the binder is in the range 1 :1 to 7:3.
Examples
The invention is further described by the following nonlimiting examples.
Example 1
An acidic, 10 wt% TiO2 dispersion of pH < 1 was prepared by mixing 2.5 parts of titanic acid suspended in water with 1 part of TiOCl2 solution (22-24 wt % TiO2, density 1.5-1. 6 g.cm-3) to obtain a clear solution and adding citric acid as stabilizer in mass ratio of 10: 1 TiO2:citric acid prior to raising the temperature to 80 °C and holding for 75 minutes and subsequent rapid cooling. The said titanic acid suspended in water was pH 5.5 and was prepared by mixing 2 parts of said TiOCl2 solution with 1 part of water and 8.8 parts 10% NaOH, keeping the temperature in the range 25-40 °C. In this example, the ratio of two masses, i.e., the mass of Ti in the aqueous TiOCl2 solution used to prepare the titanic acid suspended in water and the mass of Ti in the aqueous solution of TiOCl2 that was mixed with titanic acid to form a clear solution was 3:7.
The ion and water content were adjusted to pH 1 to 1.5 and 20 wt% TiCd so that an acidic sol of TiO2 was obtained. The acidic sol of TiO2 was adjusted to 37 wt% to arrive at a 37 wt% dispersion of particles. An amount corresponding to 5.2773 g TiO2 was taken.
Total 10 M KOH 130.56 g was added to adjust the concentration of hydroxide ions to well above 8 M.
The mixture stirred for 1 hour using a magnetic stirrer. Subsequently the mixture was divided evenly between 4 Teflon® (polytetraf louroethene ) lined autoclaves and then heated for 56 hours at 145 °C with no stirring.
After 56 hours of heating, the autoclaves were cooled ambiently to room temperature in the closed oven for 23 hours. The product in each Teflon® liner were mixed together .
To this was added 0.1 M HC1 and allowed to settle, decanting the clear supernatant. This was repeated three times. After this, an excess of 0.1 M HC1 was mixed with the decanted product and filtered. By this procedure at least a part of the K+-ions was replaced by H+-ions. The sample was then filtered slowly over several days, washing with milliQ water until pH > 3. The sample was then air-dried.
The air-dried powders were then stirred in solutions of 0.001, 0.005, 0.01 and 0.05 M NaOH to exchange the hydrogen for sodium. The amount of solution was controlled so that the calculated amount of sodium, when fully exchanged would yield the following sodium contents of the exchanged titanates: 0.001 M - 1.6%; 0.005 M - 2.7%; 0.01 M - 6.0%; and 0.05 M - 26.9%.
The four samples exchanged at these four different concentrations plus the unexchanged titanate were then divided and heated to different temperatures up to 500 °C. After heating, the powders were then subject to Raman spectroscopy. The samples include the sample heated to 400°C shown in Figure 1, 450°C shown in Figure 2 and the 500°C shown in Figure 3. Along with an unshown figure run at 350°C, these data from Figures 1, 2 and 3 are then used to calculate a bronze stability indicator, BSI shown in Figures 4 and 5. From these spectra, the bronze stability indicator, BSI was calculated using the following method. First, a background was subtracted from all spectra according to the average spectral intensity above the zero-peak and the first intensity from the sample. This background average was flat and equal to the intensity at 75 cm-1 . Next the peak height of a bronze indicator peak, B at 201.69 cm-1 was divided by the peak height of an anatase indicator peak, A at 148.68 cm-1. These peaks could easily be identified as inside the ranges of wavenumbers. This is the bronze/anatase ratio value or BAR = B/A. The BAR value was normalized to a value of 1.3, which was obtained by making the same procedure for a pure bronze phase. This gave the bronze stability indicator value or BSI, which was found to be a representative value of BAR for pure or nearly pure bronzes made using this hydrothermal method. Therefore, higher values of BAR or BSI indicate higher levels of bronze compared with anatase. Please note this is not quantitative in terms of exact amount of bronze, but systematically increases with increasing bronze to anatase, or systematically decreases with increasing anatase fraction.
This method of stabilization can be performed on small fractions of a batch of samples in order to find the BSI as a function of Na exchange and temperature. Such information will likely vary somewhat depending upon the quality and nature of the starting titanate material.
In the case where one would prefer to find an optimized stability condition as a function of temperature and Na content, say for use in a lithium ion battery anode material, the desire for thermal stability of bronze is high (high BSI) since full conversion of the titanate to TiO2 is best achieved above 300-350 °C, but the desire for high sodium content is low, since it will impact the capacity of the anode. So one can use this method to find an optimum amount of stabilizer that is high enough to give stability at a desired temperature, say 400 °C, but not too high that the capacity for lithium is negatively affected. The capacity of a battery is negatively affected by a high content of other metal ions such as Na because the other metal ions take the place of Li-ions contributing to the capacity of the battery . Example 2
Using the same titanate powder as in example 1, other ions of were exchanged in place of the H, by exchanging in solutions of LiOH, CsOH, ZnC12 and LaCls respectively at approximately 0.001, 0.005, 0.01 and 0.05 M concentrations each.
The corresponding ratios R for each case, i.e. for Li, Cs, Zn and La at the four different concentrations of 0.001 M (very low) , 0.005 M (low) , 0.01 M (high) and 0.05 M (very high) of the metal solutions. In the experiments these were target concentrations and the actual concentrations differed slightly from the target concentrations. Since the concentrations are not exact they are given as very low, low, high, and very high instead of actual values.
Figure imgf000058_0001
The underlined values fall within the formula (0.029*AWmetal - 0.10*X) ≤ R ≤ ( 0.82 * AWmetal - 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence.
Each solution contained 0.35 ± 0.03 g of the dry titanate, and 10 g of solution, and 10 g solution of varying metal content. Exact weights were recorded and the following weight and atomic ratios (relative to the air-dried titanate) were used. For each concentration of Li solution, the weight-% of Li relative to the airdried titanate was: 0.49, 0.91, 4.60 and 8.81 wt% respectively. For the Cs solution: 13.8, 17.1, 48.0 and 64.9 wt% respectively. For the Zn solution: 4.32, 8.86, 31.88 and 48.32 wt%, respectively. For the La solution: 9.55, 16.7, 50.5 and 65.3 wt%, respectively. For the ion exchange, all solutions were stirred magnetically together with the titanate samples for 20 minutes at room temperature and then transferred to an oven heated to 70 °C for an additional 30 minutes without stirring. The exchanged powders were collected by triple decantation and centrifugation with deionized water in 45 ml centrifuge tubes, and air-dried. All of the airdried, exchanged samples were then heated in air at 350 °C for 2 hours plus 400 °C for 1 hour. The samples were then split, and the splits subjected to an additional 1 hour of heating in air at 450 °C. Raman spectroscopy was run on all 32 samples. Additionally, the non-exchanged titanate was also heated in air at 350 °C for 2 hours plus 400 °C for 1 hour at the same time as the other samples. Most samples displayed Raman spectra characteristic of bronze or a bronze-like phase with either zero or trace anatase when measured in multiple spots. Two exceptions were found, one being that a consistent albeit small amount of anatase was detected in the heated, non-exchanged sample. The other was the Li exchanged samples. These displayed 1-5% anatase when heated to 400 °C (as judged by the size of the anatase peak near 150 cm-1) , although no anatase was detected in the sample exchanged in the highest concentration. For the higher temperature run, the anatase fraction increased from 1-5% at high exchange concentration, to 10-20% for the lowest exchange concentrations. Taken together these results indicate that Li is not effective in stabilizing bronze from transitioning to anatase in these samples whereas Cs, Zn and La do have a stabilizing effect .
Example 3
Stabilised anode material preparation
A stabilised bronze material was prepared by an exchange reaction similar to example 1 but now using 1 g of air dried hydrogen titanate and adding it to approximately 125g of 0.01M NaOH.
The so obtained t itanate/NaOH dispersion was stirred magnetically at room temperature for 30 minutes followed by 30 minutes heating without stirring, in an oven preheated to 65 °C, followed by a second stirring of approximately 15 minutes.
The sample was then washed in deionized water to remove excess ions and subsequently air dried.
Chemical analysis showed the atomic ratio of titanium to alkali metal (R) in the stabilized material to be 6.5, with the Na/K atomic ratio of 0.9, the potassium being unremoved alkali metal during the initial acid exchange .
The material was used in an electrode of a coin cell and its electrochemical properties were measured.
Anode preparation
A dispersion was made with the material as follows:
Samples were prepared using
1.002g third structure comprising TiO2 0.124g Super C 65 carbon black (Imerys®)
0.126g Kynar® PVDF (polyvinylidene fluoride) .
2.377g n-methylpyrrolidone (NMP)
All slurries were homogenised using a RETCH Mixer Mill MM 200 with stainless steel jars.
First the carbon black was dispersed in a 5 wt% PVDF solution for 10 min. Afterwards the active material and additional NMP was added and the slurry was homogenised for 30 min.
The slurries were coated using a K control coater with a meter bar designed to leave a wet film deposit of 100 pm .
After coating the electrode sheets were dried at 60 °C, roll pressed and dried again at 100 °C under vacuum for 10 hours. 12 mm 0 electrodes were punched and transferred to an Ar filled glovebox.
2016 coin-cells (6 cells per sample) were assembled using Li as counter electrode a Celgard 2400 PP separator and 40 pL LP40 electrolyte (IM L1PF6 in EC/DEC 1: 1 wt . ) EC/DEC is Ethylene Carbonate : Diethyl Carbonate.
Electrochemical characterisation
Electrochemical charge and discharge experiments were carried out on a Maccor 4200 and a LANHE CT2001A in a voltage window of 1-2.5 V vs. Li/Li+. 1C was defined as 330 mA/ g (TiO2) .
Two different test programs were applied. In the first program, the rate acceptance was assessed. The cells were charged and discharge at C/10, C/3, C/2, 1C, 2C, 5C, 10C and C/10 again for 5 cycles each. The last step at low currents was applied to analysed the capacity recovery.
In the second program, the cycle-life at C/2 was assessed for 200 cycles. Prior to the cycle life analysis the cells underwent 3 cycles at a low current of C/10.
Electrochemical results
All results are given in mAh per gram TiO2- The coulombic efficiency is calculated by dividing the delithiation capacity by the lithiation capacity. The lowest applied current was 33 mA/ g (C/10) and the highest 3300 mA/ g (10C) . This would translate to about 20C for LTO.
A diagram from a test cycle is shown in Figure 10.
Initial capacity at C/10 cycle 3: 175 mAh/g
Capacity at 5C (cycle 30) : 95 mAh/g
Capacity at 10C (cycle 35) : 65 mAh/g
Recovered capacity: 170 mAh/g
Capacity after 500 cycles at 3C: 130 mAh/g (160 mAh/g initial )
Coulombic efficiency in both tests: converged to > 99.5% after initial cycling.
Example 4
Niobium doped TiO2(B) was prepared with a composition identical to Example 1, except with the addition of 0.5g Nb2O5 stirred into the 37% TiO2 dispersion until well homogenised, prior to addition of 10 M KOH. The sample was divided equally into four 30 ml Teflon- lined steel autoclaves and heated at 145 °C for 44.5 hours. The sample was acid exchanged by repeated centrifugation, decantation and re- suspens ion in distilled water.
A niobium-doped bronze material was obtained by heating 2.065 g of the washed and dried acid exchanged material from example 4. The sample was calcined by heating at 140 °C for 20 minutes, 225 °C for 1 hours, 350 °C for 30 minutes and 450 °C for one hour in air. The cooled sample was weighed and the weight loss during heating was 17.5%. The sample was hand ground in a mortar and pestle and subject to x-ray diffraction and Raman spectroscopy. The sample was found to be consistent with the bronze phase of TiO2, with no detectable anatase
The calcined R value of this niobium-doped TiO2 bronze materials was 13.5. The potassium present due to incomplete removal during the acid exchange step.
Four 0.042g samples of the air-dried hydrogen titanate obtained prior to the conversion to bronze were reexchanged with 0.05M, 0.01M, 0.005M and 0.001M NaOH, respectively to obtain four metal stabilised, niobium doped titanates in the same way as example 1, with the same final target Na contents for each as was targeted in example 1.
These sodium exchanged, niobium doped titanates were calcined by heating at 140 °C for 20 minutes, 300 °C for 45 minutes, 350 °C for one hour and 450 °C for 30 minutes, 500 °C for 30 minutes and 550 °C for 30 minutes. The cooled samples were then subject to Raman spectroscopy .
The Ti/Nb ratio of the input mixture was determined as 17 and the measured ratio in the so-made bronze was also determined to be 17 by electron dispersive x-ray analysis on three separate areas of the sample indicating a homogeneous reaction of Ti and Nb oxides with KOH. A Ti:Nb ratio of 17 is within the limitation that Nb ions are added up to a Ti:Nb ratio of 8. So the Ti/K ratio and Ti/Nb ratio is considered identical in the metal stabilised niobium-doped bronzes and the niobium doped bronze with residual potassium.
A result from the example can be seen in figure 11 showing Raman spectra corresponding to metal stabilised niobium-doped bronze materials with very high to very low contents of sodium stabilisation.
It appears that with metal stabilization of niobium doped TiO2(B) at 17:1 Ti:Nb, the thermal stability of the unstabilised (or minimally stabilized) material is so improved that the need for stabilizing metal ions becomes less the more Nb is present in the precursor bronze structure likely due to a separate thermal stabilisation of the bronze arising through niobium doping. Nonetheless stabilisation originating from sodium and or potassium ions is still readily apparent in the 17:1 Ti:Nb metal stabilised bronze material of this example, but only at relatively high Na content. It is likely that the destabilization of bronze to anatase can occur for longer thermal treatments for a given temperature, therefore metal stabilization of niobium doped bronzes made by hydrothermal processing is best taken advantage at longer heating times than for non-doped bronzes, the exact temperature depending on the intrinsic thermal stability of the non-stabilised niobium-doped bronze, which is likely to be a higher temperature than for a non-niobium-doped bronze.
Example 5 Niobium doped bronze anode preparation and electrochemical characterization
Anode preparation
Anodes were prepared using the niobium-doped TiO2 bronze of example 5, calcined at a maximum temperature of 450
C .
Two electrode slurries were prepared using the following : 0.7000 g of the active material component (TiO2) . 0.2000g Super C65 carbon black (Imerys®)
2.000 g of a 5wt% solution of Kynar® PVDF polyvinylidene fluoride) 5% in n-methylpyrrolidone (NMP) and extra NMP to adjust viscosity.
These would yield a final dry cast composition of 70:20:10, TiC^icarbon black: binder calculated by weight .
To form the first slurry: i) A first mixture was made by combining 0.2g of carbon black dispersed in the 2.0 g of binder solution in a mixing cup using a vacuum centrifugal mixer running at 2000rpm for 10 minutes and then degassing under vacuum for 30 seconds . ii) A second mixture was obtained by adding 3.0 g of NMP solvent and 0.70g of active Nb-doped TiO2 material to the mixing cup containing the first mixture, followed by mixing for 5 minutes at 2000 rpm followed by degassing for 30 seconds under vacuum . iii) The second mixture was then transferred into a stainless-steel vial (10ml volume) with 1 ball (6.5g mass) and mixed in a Retsch MM 400 mixer mill at 25Hz for 10 minutes iv) Extra NMP was added to adjust viscosity for casting in 1.5g steps, with a further 2 minutes mixing at 25Hz .
To form the second slurry: i. A first mixture was made by combining 0.2g of carbon black, 0.7g of the active Nb-doped TiO2 and 3.0g NMP solvent in a stainless steel vial (10 ml) . One ball (6.5g mass) was added to the stainless steel vial and the vial shaken in a Retsch MM 400 mixer mill at 25 Hz for 5 minutes. ii. A second mixture was obtained by adding 2.0g of binder solution to the first mixture contained in the stainless steel vial obtained after (i) above and the vial was shaken in a Retsch MM 400 mixer mill at 25 Hz for 10 minutes. iii. Extra NMP was added to adjust viscosity for casting in 1.5g steps, with a further 2 minutes mixing at 25Hz .
Coating Procedure
The freshly made slurries were coated onto 20 micron thick Al foil using a K control coater with a Zhentner applicator frame designed to leave a wet film deposit of 200 micrometers.
After coating the electrode sheets were dried at 60 °C for 48 hours. For testing, 14 mm 0 electrodes were punched from the dry electrode sheet and dried at 120 °C under vacuum for 14 hours in a glove box mini chamber and transferred to an Ar filled glove box.
Coin cell assembly
2016 coin-cells (9 cells per sample) were assembled using Li metal (16 mm 0) as counter electrodes. Additionally in each cell, a Celgard 2400 PP was used as a separator, 35 pL LP4O (1M LiPF6 in EC/DEC 1:1 wt . from Sigma Aldrich) as the electrolyte and a pre-weighed punched electrode comprising the Nb-doped TiO2 bronze. The mass of the coated electrode material was determined by subtracting an average mass value for 10 punched disks of the uncoated Al foil sheet from which the electrodes were cast.
Electrochemical characterisation
A LANHE CT2001A tester was used in cycling the half cells. 1C was defined as 330 mA/ g (TiO2) .
Two different test programs were applied.
In the first program, operating on several coin cells made from electrodes obtained from the first slurry, cells were charged and discharged for 32 cycles at C/10.
In the second program, operating on several coin cells from the second slurry, cells were charged and discharged at C/10 (cycles 1-2) , C/2 (cycles 3-12) , 1C (cycles 13-22) , 2C (cycles 23-32) , 5C (cycles 33-42) and 10C (cycles 43-52) and then back to C/2 (cycles 53-62) and C/10 (cycles 63-64) to assess recovered capacity after iterated cycling and then to 1C (cycles 65-264) for assessing capacity for extended further cycling.
Electrochemical results
All results are given in mAh per gram (mAh/g) of the active Nb-doped bronze material. The coulombic efficiency is calculated by dividing the delithiation capacity by the lithiation capacity. The lowest applied current was 33 mA/ g (C/10) and the highest 3300 mA/ g (10C) . The latter would translate to about 20C for LTO.
Diagrams of the electrochemical characterisation results from two representative cells made as described above are given in Figures 12, 13 and 14.
A diagram from a test cycle for a cell made from the first slurry is shown in Figure 12.
Capacity at C/10 cycle 3: 242 mAh/g
Capacity at C/10 cycle 32: 216 mAh/g
Coulombic efficiency: 1st cycle: 89.9%; 32nd cycle: 98.8%
A diagram of the rate cycling for a cell made from the second slurry is shown in Figures 13 and 14. Figure 14 is a zoomed out view of Figure 13.
Initial capacity at C/10 (cycle 2) : 257 mAh/g
Capacity at C/2 (cycle 12) : 226 mAh/g
Capacity at 1C (cycle 22) : 213 mAh/g
Capacity at 2C (cycle 32) : 195 mAh/g
Capacity at 5C (cycle 42) : 151 mAh/g
Capacity at 10C (cycle 52) : 109 mAh/g
Recovered capacity at C/2 (cycle 62) : 218 mAh/g Recovered capacity at C/10 (cycle 64) : 229 mAh/g Recovered capacity at 1C (cycle 100) : 203 mAh/g Recovered capacity at 1C (cycle 264) : 195 mAh/g
Initial coulombic efficiency: (cycle 1) : 84.3%
Converged Coulombic efficiency: cycle 264: 99.8%
Example 6
The starting materials were a commercial TiOCl2 solution, NaOH and citric acid and deionized water. The TiOCl2 solution was received with composition of approximately 35-26% TiOCl2 , hydrochloric acid 22-24% and water 40-43%. The measured density of the TiOCl2 solution at 20°C was 1.5605 ± 0.0010 g.cm-3. 5.01g of water was added to 10.02g TiOCl2 solution with stirring and cooling to below 25 °C to obtain a diluted TiOCl2 solution. To the diluted TiOCl2 solution was added 43.85g of a solution comprising 10% by weight NaOH in water, with stirring and cooling to maintain a temperature below 25 °C. This resulted in a suspension of white titanium-containing precipitate of approximately pH 5. To this suspension was added 23.33 g of TiOCl2 solution, keeping the temperature below 25 °C until the solution became completely transparent. To this transparent or "clear" solution 0.759 g of citric acid was added under stirring until the citric acid was dissolved. To this solution 95.88g of 10% NaOH solution was added resulting in a second suspension of titanium bearing precipitate at approximately pH 4. Stirring was continued for approximately 15 minutes after the last addition of 10% NaOH.
Approximately 100 ml of the second suspension was then placed into two 50 ml centrifuge tubes and centrifuged and decanted multiple times for 2 minutes at 3000 rcf (relative centrifugal force) , each followed by addition of deionized water and resuspension after each decantation. This was repeated until the NaCl content was substantially decreased obtaining a washed precipitate. The washed precipitate was then dried in air until the material was dry and was ground to uniformity using an agate mortar and pestle to obtain a fine powder. The fine powder was then subject to analysis by Raman microscopy and X-ray powder diffraction. These analyses indicated the fine powder was substantially free of anatase. Approximately 0.3g of the fine powder was then heated in air at 350 °C for one hour to obtain a calcined powder sample. The calcined powder sample was then subject to analysis using a Raman spectrometer, yielding a spectrum indicating a high fraction of anatase. The sample was then analysed by energy dispersive x-ray analysis (EDX) using a Zeiss scanning electron microscope. The atomic titanium to sodium ratio (Ti/Na) was determined to be 4.910.75.
Example 6b
Approximately 5 g of the washed precipitate of Example 1 was suspended in an excess of 0.1 M HC1 solution and stirred overnight to replace any Na in the titanium dioxide with H ions to obtain a suspension of acid exchanged titanium dioxide. The acid exchanged titanium dioxide was then washed by repeated centrifugation and decantation to obtain a neutral suspension of washed, acid-exchanged titanium dioxide at pH 5-6. The. The washed acid-exchanged titanium dioxide was then air dried, ground and found to have a tap density of 0.8 gcnr3. The sample was then heated at 350 °C for 1 hour and its phase determined as close to 100% anatase.
Example 6c 2.974g of powder from example lb was added to a mixture of 0. IM 37.8g NaOH and 61.3g deionized water. The mixture was magnetically stirred for 15 minutes and then transferred to an oven for 1 hour, the temperature being 40°C at the end, and without stirring. The pH after removal from the oven was near neutral. The sample was then washed by centrifugation and decantation multiple times and air dried. The sample was split into two, one was clcined at 300°C for 2 hours and the other at 350°C for 1 hour, with anatase content estimated at 5-20% for the former and 5-10% for the latter.
Example 7a 6.13g of water was added to 12.27g T1OCl2 solution with stirring and cooling to below 25°C to obtain a diluted TiOCl2 solution. To the diluted T1OCl2 solution was added 54.00g of a solution comprising 10% by weight NaOH in water, with stirring and cooling to maintain a temperature below 25°C. This resulted in a suspension of white titanium containing precipitate of approximately pH 5. To this suspension was added 28.71 g of TiOCl2 solution, keeping the temperature below 25°C until the solution became completely transparent. To this transparent solution 0.925g of citric acid was added under stirring until the citric acid was dissolved. To this solution 102.035g of 10% NaOH solution was added resulting in a second suspension of titanium bearing precipitate at approximately pH 10. Stirring was continued for approximately 15 minutes after the last addition of 10% NaOH. The suspension was adjusted to approximately pH 4-5 with the addition of 4M HCl. Approximately 200 ml of the second suspension was then placed into 4 x 50 ml centrifuge tubes and centrifuged and decanted multiple times for 2 minutes at 3000 ref, each followed by addition of deionized water and resuspension after each decantation. This was repeated until the NaCl content was substantially removed obtaining a washed precipitate comprising a titanate. The washed precipitate was then dried in air and ground to uniformity using an agate mortar and pestle to obtain a fine titanium dioxide powder with tap density approximately 1.2 g.cm-3.
Example 7b
The fine powdered titanium dioxide of example 2a was then subject to analysis by Raman microscopy and X-ray powder diffraction. These analyses indicated the fine powder was a titanium dioxide phase similar in structure to H-titanium dioxide or Na-titanium dioxide and free of any detectable anatase. Approximately 0.3g of the fine powder was then heated in air at 350 °C for one hour to obtain a calcined powder sample. The calcined powder sample was then subject to analysis using Raman spectroscopy and x-ray powder diffraction, yielding curves indicating up to 5-20% anatase and 80-95% bronze and minor NaCl. The sample was then analysed by energy dispersive x-ray analysis using a Zeiss SEM. The atomic titanium to sodium ratio (Ti/Na) was found to be 2.13: 1 when subtracting away Na that was bonded to Cl in residual NaCl, here all Cl was assumed to be in NaCl, so the amount of Na subtracted from the total was equivalent to the atomic % of Cl.
Example 7c The calcined sample of Example 2b was washed to remove remaining soluble salt such that NaCl was not detected via XRD, and was then dried at 70 °C overnight. This sample was then analysed by Raman spectroscopy and found to have approximately 50% anatase and 50% bronze phases.
Example 7d
By addition of a conducting material (carbon black, TIMCAL™ SUPER C65 Conductive Carbon Black) and a binder ( a =fluoride , Kynar PVDF RC - 10215), the dried sample of example 2c was made into an electrode and tested in an electrochemical half-cell. The composition was applied in a slurry was 8: 1:1 act ive : carbon black:binder and the active loading of calcined material was between 2.7 and 3.2 mg cm-2. "Active" denotes the calcined material comprising titanium dioxide in bronze form. A copper foil of the electrode used was 20 pm thick with average weight 16.1 mg cur2. The capacity at cycle 3 was approximately 92 mAh/g at C/10 (see Figure 15) and an approximately stable capacity of 80 mAh/g and a Coulombic efficiency levelling out at 100% after about 5-10 cycles out to 250 cycles at C/2 (see Figure 16) .

Claims

Claims
1. A method for manufacturing a component material of a battery electrode, the material comprising TiO2, wherein the TiO2 comprises a fraction of TiO2(B) , titanium dioxide in bronze phase, the method comprising the steps of: a) providing an aqueous solution comprising TiOCl2, HC1, and an alpha-hydroxy acid, b) increasing the pH of the solution until a precipitate is obtained, wherein the temperature is above 0 °C and below 55 °C, and c) calcining the obtained precipitate during a time range of 5 minutes to 48 hours at a temperature in the interval 110-600 °C to obtain a calcined material comprising the titanium dioxide bronze material.
2. The method according to claim 1, wherein the aqueous solution comprising TiOCl2 is provided by at least partial hydrolysis of TiCl4.
3. The method according to claim 1, wherein the aqueous solution comprising TiOCl2 is provided by dissolving at least one titanic acid with the general formula TiOx (OH) 4-2x, wherein x is 0 or 1, in an aqueous solution comprising at least one compound selected from the group consisting of TiOCl2, TiCl4 and HCl so that a clear solution is obtained, while keeping the temperature below 30 °C.
4. The method according to claim 3, wherein the at least one titanic acid is made from TiOCl2 by addition of an aqueous solution of a base until precipitation.
5. The method according to any one of claim 1-4, wherein the obtained precipitate is washed in water between steps b) and c) .
6. The method according to any one of claim 1-5, wherein the method is carried out at a pressure p being ambient pressure ±20%.
7. The method according to any one of claims 1-6, wherein pH is increased in step b) by addition of NaOH.
8. The method according to any one of claims 1-7, wherein the at least one alpha hydroxy acid is citric acid .
9. The method according to any one of claims 1-8, wherein the aqueous solution provided in step a) is clear .
10. The method according to any one of claims 1-9, wherein the precipitate is dried and optionally ground between steps b) and c) .
11. The method according to claim 10, wherein the precipitate is dried at a temperature of between 300 and 500 °C.
12. The method according to any one of claims 10- 11, wherein the precipitate is dried for a time period of between 1 and 2 h.
13. The method according to any one of claims 5-12, wherein step b) further comprises the washed precipitate being suspended in an aqueous acid solution with a pH lower than 3 and stirred to replace at least a part of the cations in the titanium dioxide with H+ ions to obtain a suspension of acid exchanged titanium dioxide.
14. The method according to claim 13, wherein step b) further comprises the acid exchanged titanium dioxide being washed by repeated centrifugation and decantation.
15. The method according to any one of claims 1-14, wherein the obtained precipitate in step b) is separated from the remaining liquid between steps b) and c) .
16. The method according to any one of claims 1-15, wherein no transition metal ions except titanium ions are added in step a) or b) .
17. The method according to any one of claims 1-16, wherein at least one type of ions selected from the group consisting of Na+, K+, Rb+ and Cs+, are added at any point before step c) .
18. The method according to any one of claims 1-17, wherein Nb-ions are added at any point before step b) .
19. The method according to any one of claims 1-18, wherein the pH in step b) is increased also after the precipitate is obtained and wherein the pH is increased to a value in the range 7-10.
20. The method according to any one of claims 1-19, wherein the calcination in step c) is carried out at a temperature in the interval 300-450 °C.
21. The method according to any one of claims 1-19, wherein the calcined material is washed to reduce the content of soluble ions and then dried.
22. The method according to any one of claims 1-21, wherein at least one conducting material and least one binder is added to the calcined material to obtain an electrode material for a battery.
23. The method according to any one of claims 1-22, wherein at least one precursor for a conducting material is added before the calcination to obtain an electrode material for a battery.
24 . The method according to claim 22, wherein the conducting material is carbon black.
25. The method according to claim 22 or 24, wherein the at least one conducting material, the at least one binder and the calcined material are mixed in a slurry.
26. The method according to any one of claims 22, 24 or 25, wherein the content of the calcined material in the electrode material is 70-90 wt%.
27. The method according to any one of claims 1-26, wherein a BET specific surface area of the calcined material according to ISO 9277 is in the range of 2-30 m2/g .
28. The method according to any one of claims 1-27, wherein: the aqueous mixture obtained in step a) comprises a titanium dioxide bronze precursor with the general formula A2TinO2n+1 • mH2O, and an anatase precursor, wherein A is hydrogen or a metal in cationic form, n is an integer from 3 to 6, m is a number from 0 to 2.5, wherein the content of metal ions is in the range 1.5 to 30 wt%, wherein the metal ions are at least one type of ions of a metal selected from the group consisting of rare earth metals, alkaline earth metals, transition metals, sodium, potassium, rubidium, caesium, zinc, lanthanum, indium, tin, lead, bismuth, calcium, magnesium, titanium, niobium, rubidium, lithium, silver, copper, and cadmium.
29. The method according to claim 28, wherein the temperature in step c) is in the interval 300-500 °C and content of metal ions is in the range 1.5 - 30 wt%.
30. The method according to claim 28, wherein the temperature in step c) is in the interval 300-400 °C and content of metal ions is in the range 1.5 - 6 wt%.
31. The method according to any one of claims 28-
30, wherein the content of metal ions is adjusted to the desired value by ion exchange.
32. The method according to any one of claim 28-31, wherein the content of metal ions is adjusted by additions of the desired metal ions during the manufacture of the aqueous mixture.
33. The method according to any one of claim 1-32, wherein the manufactured component material of the battery electrode comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AWmetal - 0.10*X) ≤ R ≤ ( 0.82 *AWmetal - 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence.
34. The method according to any one of claim 1-33, wherein the obtained calcined material is utilized as a component in an electrode for a battery, when a battery is manufactured, said battery comprising at least one electrochemical cell, and wherein the at least one electrochemical cell comprises at least two electrodes (1,2) and at least one electrolyte (7) , wherein at least one of the electrodes (1,2) comprises a) the obtained calcined material, b) at least one conducting material, and c) at least one binder.
35. A component material of a battery electrode, the material comprising TiO2, wherein the TiO2 comprises a fraction of TiO2 , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, wherein the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AWmetal > 0.10*X) ≤ R ≤ ( 0.82 *AWmetal - 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence.
36. The material according to claim 35, wherein the metal ions are at least one type of ion of a metal selected from rare earth elements.
37. The material according to claim 35, wherein the metal ions are at least one type of ion of a metal selected from transition metals, which can give rise to cations with an incomplete d sub-shell.
38. The material according to claim 35, wherein the metal ions are at least one type of ion of a metal selected from alkaline earth metals and transition metals .
39. The material according to claim 35, wherein the metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium, caesium, zinc and lanthanum.
40. The material according to claim 35, wherein the metal ions are at least one type of ion of a metal selected from the group consisting of indium, tin, lead, and bismuth.
41. The material according to any one of claims 35-
40, wherein the Ti:metal atomic ratio R in the material is greater than 4:1.
42. The material according to any one of claims 35-
41, wherein a BSI (Bronze stability indicator) value is above 0.8 for the TiO2, wherein the BSI value is calculated from laser Raman spectroscopy of the TiO2, according to the following method: the instrument is calibrated against a silicon wafer standard, the intensity for the Bg(2) bronze peak located in the interval 190 - 205 cm-1 minus the background intensity is divided by the intensity for the Eg ( 1 ) anatase peak located in the interval 140 - 160 cm-1 minus the background intensity and then the resulting ratio is divided with a normalization factor which is calculated as the intensity of the Eg ( 1 ) anatase peak minus the background intensity divided by the intensity for the Bg ( 2 ) bronze peak minus the background intensity for pure TiO2 (B) , wherein the background intensity as calculated as the average intensity in the region with a wavenumber higher than the zero-peak and lower than the intensity originating from the sample.
43. The material according to any one of claims 35-
42, wherein the metal ions are of at least one type of ion selected from the group consisting of sodium, and potassium.
44. The material according to any one of claims 35-
43, wherein the material comprises Nb ions.
45. The material according to any one of claims 35-
44, wherein the material comprises Nb ions so that the Ti:Nb ratio is 8: 1 or lower.
46. The material according to any one of claims 35-
45, wherein the material comprises at least one type of ion selected from the group consisting of calcium and magnesium.
47. The material according to any one of claims 35- 46, wherein the material comprises at least one type of ion selected from the group consisting of silver, copper, and cadmium.
48. The material according to any one of claims 35- 47, wherein the material comprises at least one rare earth metal .
49. The material according to any one of claims 35-
48, wherein the BET specific surface area according to ISO 9277 of the TiO2 is in the range 2-30 m2/g.
50. The material according to any one of claims 35-
49, wherein R fulfils:
( 0.20*AWmetal - 0.10*X) ≤ R ≤ ( 0.82*AWmetal - 0.10*X) .
51. The material according to any one of claims 35-
50, wherein the TiO2 constitutes 70-90 wt% of the electrode material.
52. A battery comprising at least one electrochemical cell, said at least one electrochemical cell comprises at least two electrodes (1,2) and at least one electrolyte (7) , wherein at least one of the electrodes (1,2) comprises a) a material comprising TiO2, wherein the TiO2 comprises a fraction of TiO2 , titanium dioxide in bronze phase, wherein the material comprises at least one type of metal ion, b) at least one conducting material, and c) at least one binder, wherein for the material the Ti to metal ion atomic ratio R fulfils the following condition ( 0.029*AWmetal > 0.10*X) ≤ R ≤ ( 0.82*AWmetal - 0.10*X) , wherein AWmetal is the atomic weight of the metal and X is the metal valence .
53. The battery according to claim 52, wherein the metal ions are at least one type of ion of a metal selected from rare earth elements.
54. The battery according to claim 52, wherein the metal ions are at least one type of ion of a metal selected from transition metals, which can give rise to cations with an incomplete d sub-shell.
55. The battery according to claim 52, wherein the metal ions are at least one type of ion of a metal selected from alkaline earth metals.
56. The battery according to claim 52, wherein the metal ions are at least one type of ion of a metal selected from the group consisting of sodium, potassium, rubidium, caesium, zinc and lanthanum.
57. The battery according to claim 52, wherein the metal ions are at least one type of ion of a metal selected from the group consisting of indium, tin, lead, and bismuth.
58 . The battery according to any one of claims 52-
57, wherein the Ti:metal atomic ratio R in the material is greater than 4:1.
59. The battery according to any one of claims 52- 58, wherein a BSI value is above 0.8 for the TiO2, wherein the BSI value is calculated from laser Raman spectroscopy of the TiO2, according to the following method: the instrument is calibrated against a silicon wafer standard, the intensity for the Bg(2) bronze peak located in the interval 190 - 205 cm-1 minus the background intensity is divided by the intensity for the Eg ( 1 ) anatase peak located in the interval 140 - 160 cur 1 minus the background intensity and then the resulting ratio is divided with a normalization factor which is calculated as the intensity of the Eg ( 1 ) anatase peak minus the background intensity divided by the intensity for the Bg ( 2 ) bronze peak minus the background intensity for pure TiO2 (B) , wherein the background intensity as calculated as the average intensity in the region with a wavenumber higher than the zero-peak and lower than the intensity originating from the sample.
60. The battery according to any one of claims 52- 59, wherein the metal ions are of at least one type of ion selected from the group consisting of sodium, potassium.
61 . The battery according to any one of claims
Figure imgf000083_0001
60, wherein the material comprises Nb ions.
62 . The battery according to any one of claims 52- 61, wherein the material comprises Nb ions so that the Ti:Nb ratio is 8: 1 or lower.
63. The battery according to any one of claims 52- 62, wherein the material comprises at least one type of ion selected from the group consisting of calcium and magnesium.
64 . The battery according to any one of claims 52- 63, wherein the material comprises at least one type of ion selected from the group consisting of silver, copper, and cadmium.
65. The battery according to any one of claims 52- 64, wherein the material comprises at least one rare earth metal .
66. The battery according to any one of claims 52-
65, wherein the BET specific surface area according to
ISO 9277 of the TiO2 is in the range 2-30 m2/g.
67 . The battery according to any one of claims 52-
66, wherein R fulfils:
( 0.20*AWmetal - 0.10*X) ≤ R ≤ ( 0.82*AWmetal - 0.10*X) .
68 . The battery according to any one of claims 52-
67, wherein the conducting material is carbon black.
69. The battery according to any one of claims 52-
68, wherein the TiO2 constitutes 70-90 wt% of the electrode material.
70. The battery according to any one of claims 52-
69, wherein the wt% ratio between the conducting material and the binder is in the range 1:1 to 7:3.
71. The battery according to any one of claims 52-
70, wherein the battery is comprised in a vehicle or machine .
72. The battery according to claim 71, wherein the vehicle is chosen from the group consisting of cars, motorcycles, buses, bikes, ferries, boats, trains, tractors, cranes, fork-lifts, drilling vehicles, hoists, trams, trolleys, fork-lifts, loaders, bulldozers, excavators, graders, scrapers, boring machines and trenchers.
73. The battery according to any one of claims 52- 70, wherein the battery is comprised in a consumer electronic device.
74. The battery according to claim 73, wherein the consumer electronic device is chosen from the group consisting of digital telephones, laptops, pads and tablets, digital audio devices and headphones, portable speakers and amplifiers, cameras, radio devices, displays and screens, vacuum cleaners, power blocks, lighting devices, wearable devices, drones and radiocontrolled devices.
75. The battery according to any one of claims 52- 70, wherein the battery is comprised in a portable power tool .
76. The battery according to claim 75, wherein the portable power tool is chosen from the group consisting of drills, drivers, circular saws, reciprocating saws, jigsaws, band saws, miter saws, power hammers, sanders, grinders, routers, LED lighting, power packs, vacuum devices, soldering units, power wrenches and ratchets, multi-tools, cordless fans and blowers, trimmers, mowers, snow shovels, chain saws, polishers and buffers.
77. The battery according to any one of claims 52- 70, wherein the battery is comprised in an energy storage device.
78. The battery according to claim 77, wherein the energy storage device is comprised of one or more items in the group consisting of modules, packs, racks, containers, computer controllers, thermal management systems, mechanical stabilizers, shock absorbers, frames, bus bars, fire protection and thermal runaway systems, filters and gas detectors.
79. The battery according to claim 77, wherein the energy storage device is comprised in one or more of systems related to - solar energy storage, wind energy storage, hydroelectric energy, wave energy, municipal storage, industrial plant energy storage, household energy storage, recovered energy storage, energy utility provider storage.
80. A slurry for making a battery electrode comprising at least one conducting material, at least one binder and a calcined material manufactured according to any one of claims 1-34.
81. A battery electrode comprising a mixture of at least one conducting material, at least one binder and a component material according to any one of the component material claims 35-51.
82. The battery electrode of claim 81, wherein the mixture is in a slurry state prior to its setting and forming of the electrode.
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