SE544707C2

SE544707C2 - Manufacture of a titanium dioxide bronze material

Info

Publication number: SE544707C2
Application number: SE2050955A
Authority: SE
Inventors: Anders Teigland; Andreas Westermoen; Hjørdis Skår; Robert Corkery
Original assignee: Tiotech As
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2022-10-18
Also published as: SE2050955A1

Abstract

The present invention relates to 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 a 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, 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).

Description

MANUFACTURE OF A TITANIUM DIOXlDE BRONZE MATERIAL Technical Field The invention relates to a method for manufacturing a material comprising titanium dioxide in bronze form, In particular, it relates to a methqd of stabilizing the material during the manufacture anß prevent the formation of titanium dioxide in anatase form thereby increasing the frection of titanium dioxide in bronze form.

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 temperaturemaking TiO2(B) process step, greater than approx. °C to make a bronze precursor or c) 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% Thus, loss on first cycle. the bronze polymorph lO 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 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.

Summary objec: of the present invention to alleviate at least some of the problems in the prior art and to provide a method for manufacturing titanium dioxide in bronze form. It has been discovered that it is possible to improve the manufacture of a TiO2(B) bronze material. It has been discovered that addition 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 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 A2Ti¿bnHJmH2O, and an anatase precursor, wherein A is a 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, caesium, rubidium, zinc, lanthanum, and tin, and CT 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)L wherein at least one conducting material and at least one binder is added to the calcined material to obtain an electrode material for a battery.

In a second aspect there is provided a battery having an electrode comprising a calcined material manufactured according to the method.

In a seeend-third aspect there is provided an 'lm-w nw M4. +4+-»»n411m A4 4A LJ. LL/LLILL/LLLL \J._L .LLA lectrode material for a O battery, wherein the material contains 70-90 wt 6 of calcined titanium dioxide bronze having a BET specific surface area according to ISO 9277 in the range 2-manufactured according to the method of any one and 30 - ITQ/q, of method claims 1-17, 10 wt% of a mixture of a conducting material and a binder.-manufaetured 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 increased.

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 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* in the 0 M spectrum is assigned to anatase. The peak at “B' near 200 cm* is assigned to a bronze or bronze- like phase of titanium dioxide. A *bronze stability indicator' is calculated dividing the peak height of B by the peak height at A and normalizing by a factor of 1.3. The spectra at NaOH concentrations > 0M have a flat or nearly flat background between 130-180 cm*, indicating no or little transition of the bronze or bronze like phase to anatase at 400°C. 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 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 spectra at NaOH concentrations > 0.005 M have a flat or nearly flat background between 130-180 cmﬂ, indicating no or little transition of the bronze or bronze like phase to anatase at 450°C.

Figure 3 shows representative Raman spectra of hydrogen titanate powders 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 spectra at NaOH concentrations 0.05M has a flat or nearly flat background between 130-180 cm*, indicating no or little transition of the bronze or bronze like phase to anatase at 500°C. 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. Note lO 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, independent of the starting NaOH concentration. Here the BSI and clearly goes up as a function of sodium exchange into the titanate.

Figure 5 shows the same data as in Figure 4 was re- plotted 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 according to the invention comprising a working anode (l), a counter electrode (2), (3), casing (4), (5), and a gasket (6). In this particular embodiment the working anode (l) a separator a lower an upper casing comprises an electrode material made by the method according to the invention.

Figure 7 shows a flow chart of the method according to the present invention.

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 101, 275-295 (1992) Mater. 17, State Chem. and for example by Zukalova et al., Chem. 1248-1255 (2005), both of which are explicitly incorporated herein by reference. Feist and Davies note that layered bronze precursor titanates of formula A2Ti¿bnH comprise titanate sheets that stack in an ABA sequence. Also considering the water molecules, the general formula is A2Ti¿bnH_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 TiOoctahedra, 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, Na2Tiﬂh with n=3 is a step 3 layered titanate with AAA stacking, and H2Tiﬂh, K2Ti4b, H2Ti4b.H2O and Cs2Ti5OU H2Ti5OU.H2O are step 3, 4 and 5 layered titanates with ABA sequence, respectively.

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). An intermediate formed at 140°C in the conversion of H2Ti¿h, is an ABA stacked (non-layered) tunnel structure with formula EhTi6OU, and then a bronze-like structure forms on further heating to 225°C with formula H@¿Ti30@25, which on further heating above 280°C forms TiO2(B).

Other ABA stacked intermediates occur in the heating lO of step 4 and 5 layered titanates. At or above about 500° C bronze converts to anatase.

*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 where [ ] formula HXTi;X[ represents a crystal ix/Ål 04/ vacancy with sheets of flat rather than corrugated TiO6 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.

Thus 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 300-500°C by heating these anatase precursors, any bronze will be converted to lO anatase because the anatase can act as a nucleation site and is more stable than bronze.

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 lOcm path-length of the solution held in a glass pipe. *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.

In the first aspect there is provided 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 A2Ti¿bnH_mH2O, and an anatase precursor, wherein A is a 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, 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).

The titanate is a compound comprising Ti covalently bound to O, where cations are associated and bound by electrostatic forces. In the general formula for the titanate A2Ti¿bnﬂ mH2O, it is thus conceived that A is in ionic form, whereas Ti and O are covalently bound. The hydrogen or a metal in cationic form is thus a proton or a positively charged metal ion. Such cations including protons can be exchanged by ion exchange. For instance, a proton can be exchanged for another cation such as a sodium cation. n is an integer from 3 to 6. The resulting titanates H2T13O7, H2T14O9, H2T15O11, and H2T16O13 aIG knOWn in thG aIt.

The content of cations is calculated as wt% based on the total weight of the titanate.

As can be seen from the experimental data, if the temperature is higher more cations are required for the stabilization, but if the temperature is kept low, a lower amount of cations is required. In one embodiment, the temperature in step b is in the interval 300 - 500 °C lll and content of metal ions is in the range l.5 - 30 wt%. In an alternative embodiment, the temperature in step b is in the interval 300 - 400 °C and content of metal ions is in the range l.5 - 6 wt%. In yet another alternative embodiment the temperature in step b is in the interval 350 - 450 °C. In still another alternative the temperature in step b is in the interval 400 - 500 °C. The content of metal ions can be adjusted to the desired value in several ways. In one embodiment the content of metal ions is adjusted during the manufacture of the titanate by use of suitable amounts of the desired ions. This has the advantage the desired amount of metal ions are achieved directly without an addition ion exchange step. Alternatively, the content of metal ions is adjusted by an ion exchange step, where for instance protons are exchanged with the desired metal ions. Also a combination of adjustment methods are envisaged.

The titanate starting material, i.e. the material with the general formula A2Ti¿bnHJmH2O can be provided in several ways. There are commercially available titanates, which can be purchased. Alternatively, the titanate can be made from other substances. In one embodiment, the titanate is obtained by providing an aqueous solution comprising TiOCl2, and HCI, and thereafter increasing the pH and/or the temperature of the solution until a precipitate comprising the titanate is obtained. In one embodiment, the precipitate is washed in water. In another embodiment, the precipitate is dried. In a further embodiment, the precipitate is dried and ground.

In one embodiment, the aqueous solution comprises an alpha hydroxy acid in addition to TiOCl2, and HCI. In one embodiment the aqueous solution is clear.In another embodiment, the aqueous solution comprising TiOCl2 is provided by at least partial hydrolysis of TiCl In another embodiment the aqueous solution comprising TiOCl2 is provided by dissolving at least one titanic acid with the general formula TiOX(OH)44X, wherein X is 0 or 1, in an aqueous solution comprising at least one compound and selected from the group consisting of TiOCl2, TiClM HCl so that a clear solution is obtained, while keeping the temperature below 30 °C. In one embodiment, 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.

The calcination, i.e. a heat treatment is carried out so that the organic material including the alpha- hydroxy acid is removed. Water is also removed during heating. 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 such as in the interval 300-400 °C together with a longer calcination time, or a higher temperature in the interval 300-500 °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 thecalcination is in one embodiment, 5 minutes tohours. As a guidance, a shorter calcination time is suitably selected for very small samples and a longer calcination time is suitably selected for larger batches.

In one embodiment, the method is carried out at a pressure p being ambient pressure f20%. In a variant embodiment, the method is carried out at ambient pressure. Ambient pressure is the atmospheric pressure at which the method is carried out.

In one embodiment, the at least one alpha hydroxy acid is citric acid.

In one embodiment, no transition metal ions except titanium ions are added.

Lighter ions are suitably chosen if the final material is to be made lightweight. Thus, for instance sodium ions are preferred over caesium ions if the weight of the final material is the most important factor.

In one embodiment, Nb-ions are added at any point before step c). Suitably 0.1 to 20 wt% Nb-ions could be added calculated based on the total weight of the material. The Nb-ions have the advantage of improving the conductivity.

In one embodiment, the pH in step b) is increased 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 material is reversed to become negative so that cations are more attracted to the material.In order to obtain an electrode material for use in a least one added to battery, in one embodiment, of the method at conducting material and least one binder are 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 the calcined material, 6-7 wt% carbon black and 4-3 wt% binder.

In one embodiment, 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. In another embodiment, the metal ions are at least one type of ions of a metal selected from the group consisting of sodium, potassium, zinc, caesium, and lanthanum.

In the second aspect there is provided a battery having an electrode comprising a calcined material manufactured according to the method.

In one embodiment, the BET specific surface area of the manufactured calcined material is in the range 2- m?/g, according to ISO 9277. Such a small specific area in a battery electrode material has the O ”v” f* -'\ I: fal/ii. J. LJUVÉ, advantage that various side reactions are suppressed.

In the third aspect there is provided 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 H9/g, manufactured according to the method of any one of claims 1-20, and 30 - 10 wt% of a mixture of a conducting material and a binder.

In one embodiment the wt% ratio between the conducting material and the binder is in the range 1:1 to 7: In one embodiment the conducting material is carbon black.

In one embodiment the 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. In one embodiment the calcination temperature when manufacturing the titanium dioxide bronze is in the range 300-500 °C. In one embodiment the calcination temperature when manufacturing the titanium dioxide bronze is in the range 300-400 °C. In one embodiment the calcination temperature when manufacturing the titanium dioxide bronze is in the range 400-500 °C. In one embodiment the calcination temperature when manufacturing the titanium dioxide bronze is in the range 400-500 °C. In one embodiment the calcination temperature when manufacturing the titanium dioxide bronze is in the range 350-450 °C. In one embodiment the calcination temperature when manufacturing the titanium dioxide bronze is in the range 450-500 °C.

In one embodiment the titanium dioxide bronze comprises at least one type metal ion of selected from the group consisting of ions of sodium, potassium, caesium, rubidium, zinc, lanthanum, and tin. Examples The invention is further described by the following non-limiting examples.

ExampleAn acidic, 10 wt% TiO2 dispersion of pH <1 was prepared by mixing 2.5 parts of titanic acid suspendedin water with 1 part of TiOCl2 solution (22-24 wt % TiO2, density 1.5-1.6 g.cm*) 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 The subsequent rapid cooling. 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: The ion and water content were adjusted to pH 1 to 1.and 20 wt% TiO2 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® (polytetraflouroethene) 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 for23 hours. The product in each Teflon® liner were mixed together.

To this was added 0.1 M HCl and allowed to settle, decanting the clear supernatant. This was repeated three times. After this, an excess of 0.1 M HCl was mixed with the decanted product and filtered. By this procedure at least a part of the K*-ions were 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 500 °C. After heating, the powders were then subject to Raman spectroscopy. The Raman spectra are shown in the figures below. From these spectra, a bronze stability indicator, BSI was calculated. First a background was subtracted from all spectra according to the spectral intensity nearcm*. Next the peak height of a bronze indicator peak, B at 201.69 cm* was divided by the peak height of an This is the anatase indicator peak, A at 148.68 cm*. bronze/anatase ratio value or BAR = B/A. The BAR valuewas normalized to a value of 1.3 to obtain 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 effected by a high content of other metal ions such as Na because the other metal ions take theplace of Li-ions contributing to the capacity of the battery.

ExampleUsing 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, ZnCl2 and LaClrespectively at 0.001, 0.005, 0.01 and 0.05 M concentrations each. Each solution contained 0.35f0.g of the dry titanate, and 10g of solution. For each concentration of Li solution, the weight % of Li relative to the air-dried 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.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 air-dried, exchanged samples were then heated in air at 350 °C °C for 1 hour. for 2 hours plus 400 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 The was detected in the heated, non-exchanged sample. 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*), 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% to 10-20% at high exchange concentration, 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.

Claims

1. A method for inhibiting the formation of anatase during manufacture of a material comprising wherein the method TiO2(B), titanium dioxide bronze, comprising the steps of: a)providing an aqueous mixture comprising a titanium dioxide bronze precursor with the general formula AQTinOmH¿.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, 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), wherein at least one conducting material and least one binder is added to the calcined material to obtain an electrode material for a battery.

2. The method according to claim 1, 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%.

3. The method according to claim 1, 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%. lO

4. The method according to any one of claims l-3, wherein the aqueous mixture is obtained by providing an aqueous solution comprising TiOCl2, and HCl, and thereafter increasing the pH and/or the temperature of the solution until a precipitate comprising the aqueous mixture is obtained.

5. The method according to claim 4, wherein the aqueous solution comprising TiOCl2 is provided by at least partial hydrolysis of TiCl

6. The method according to claim 4, wherein the aqueous solution comprising TiOCl2 is provided by dissolving at least one titanic acid with the general formula TiOX(OH)44X, wherein x is O or l, in an aqueous solution comprising at least one compound selected from and HCl so that a the group consisting of TiOCl2, TiClh clear solution is obtained, while keeping the temperature below 30 °C,

7. The method according to claim 6, wherein the at least one titanic acid is made from TiOCl2 by addition of an aqueous solution of a base until precipitation.

8. The method according to any one of claim l-7, wherein the content of metal ions is adjusted to the desired value by ion exchange.

9. The method according to any one of claim l-7, wherein the content of metal ions is adjusted by additions of the desired metal ions during the manufacture of the aqueous mixture.

10. The method according to any one of claim 1-9, wherein the method is carried out at a pressure p being ambient pressure f20%.

11. The method according to any one of claims 1- 10, wherein no transition metal ions except titanium ions are added.

12. The method according to any one of claims 1- 11, wherein Nb-ions are added at any point.

13. The method according to any one of claims 1: 12, wherein the conducting material is carbon black.

14. The method according to any one of claims-12 er 1:13, wherein the at least one conducting material, the least one binder and the calcined material are mixed in a slurry.

15. The method according to any one of claims 12- 14, wherein the content of the calcined material is 70-90 Wt%.

16. The method according to any one of claims 1- 15, wherein a BET specific surface area according to ISA 9277 of the calcined material is in the range of 2-30 m?/g.

17. The method according to any one of claims 1- 16, wherein the metal ions are at least one type of ions of a metal selected from the group consisting of zinc, caesium, lithium and sodium, potassium, lanthanum.

18. A battery having an electrode comprising a calcined material manufactured according to any one of method claims 1-

19. The battery according to claim 18, wherein the BET specific surface area according to TSG 9277 of the calcined material is in the range 2-30 m?/g.

20. 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 H9/g, manufactured according to the method of any one of method claims 1-17, and 30 -wt% of a mixture of a conducting material and a binder.

21. The electrode material of claim 20, wherein the wt% ratio between the conducting material and the binder is in the range 1:1 to 7:

22. The electrode material of any one of claim 20 or 21, wherein the conducting material is carbon black.

23. The electrode material of any one of claims 20 - 22, 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.

24. The electrode material of any one of claims 20- 23, wherein the titanium dioxide bronze comprises at least one type metal ion of selected from the group consisting of ions of sodium, potassium, caesium, rubidium, zinc, lanthanum, and tin.