Classifications

• • 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
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/134—Electrodes based on metals, Si or alloys
• • 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
  • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
  • H01M4/386—Silicon or alloys based on silicon
• • 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
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/624—Electric conductive fillers
  • H01M4/625—Carbon or graphite
• • 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
• • 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
  • H01M2004/021—Physical characteristics, e.g. porosity, surface area
• • 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
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/027—Negative electrodes
• • 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
  • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
• • 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
  • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
  • H01M4/387—Tin or alloys based on tin
• • 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
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the invention relates to anodes of lithium-ion batteries with porous anode coatings.
• Rechargeable lithium-ion batteries are now the practical electrochemical energy storage devices with the highest gravimetric energy densities of, for example, up to 250 Wh / kg.
• lithium-ion batteries during removal or storage of electrical energy, lithium ions are transported between the anode, sometimes called the negative electrode, and the cathode of the battery.
• the electrode material must contain pores in which electrolyte is used as a medium for lithium-ion transport. The amount of electrolyte thus determines the minimum porosity of such batteries.
• Conventional lithium-ion batteries contain graphitic carbon as electrode active material for storage of lithium ions. Graphite carbon undergoes no significant change in volume during storage or during the removal of lithium ions, so that no additional porosity is required for this purpose.
• a disadvantage of graphitic carbon is its relatively low electrochemical capacity which, in the case of graphite, is at most 372 mAh per gram, corresponding to only about one tenth of the lithium metal theoretically achievable electrochemical capacity.
• alternative materials for anodes have long been sought, in particular in the area of lithium-alloyed (semi-) metals, such as silicon, tin or lead, compared to graphite (372 mAh / g) have particularly high material capacities of up to 4200 mAh / g.
• a major challenge for the use of these materials is their large volume change in the course of storage or removal of lithium, since this increases the volume of, for example, silicon, tin or lead by up to 300%.
• Such extreme volume changes lead to a strong mechanical stress on the electrode structure, whereby the anode / electrode structure and thus the lithium-ion battery is damaged more and more during the charging and discharging cycles.
• the electrodes are provided with additional pores, which are intended to absorb the increase in volume of the active material when storing the lithium ions.
• this strategy inevitably involves the disadvantage that because of the additional pores, the electrodes have a correspondingly reduced material density and thus also a lower volumetric capacity or corresponding cells have a lower energy density. This goes against the goal of increasing the electrochemical capacities of the lithium-ion batteries, which was the starting point for the replacement of graphitic carbon by (semi-) metals with high lithium material capacities, such as silicon, tin or lead.
• the lithium Ion-storing active material encapsulated in a composite solution in porous composites To solve the problems associated with the high volume expansion of the anode active material, the lithium Ion-storing active material encapsulated in a composite solution in porous composites.
• the pores of a composite are designed to absorb volume expansion of the lithium-ion-storing active material without changing the volume of a composite particle.
• the production of such composites is complicated.
• US2014030599 AA describes a porous silica-based composite as an active material, wherein lithium is dispersed in the composite and the silicon oxide core is coated with carbon.
• the inherent porosity of the composite material is 5 to 90%.
• US2015380733 AA describes a porous active material for the negative electrode of a lithium-ion battery based on a core of silicon and a metal silicide and a sheath of porous silicon.
• the inner porosity of the shell is in the range of 20 to 80%.
• a carbon layer can be applied to the surface.
• inherently porous active materials are employed to provide the free volume to buffer the volume expansion of the lithium ion-storing active material.
• No. 9196896 B describes a silicon-based active material which contains an Si phase, an SiO x phase (0 ⁇ x ⁇ 2) and a SiO 2 phase and which has a porosity of 7-71%.
• US 2015072240 A describes porous silicon or Si-O x (0 ⁇ x ⁇ 2) with open, non-linear pores in the surface of the particles, wherein the porosity of the particles are in the range of 5 to 90% and by BET measurements or mercury porosimetry can be determined. Porosities of the electrode coatings containing these materials are not mentioned.
• WO2016 / 092335 describes an electrode for a metal-ion battery which consists of a Abieiter and an active material layer containing porous particles of an electrochemically active material, such as silicon, tin or aluminum, which are 0.5 to 18 m in size and have an internal porosity of 30 to 90%. In addition, there are 2 to 30% in the electrodes Porosity between electrode components (defined by the area fraction of interparticle pores in an EM image from the cross-section of the electrode). However, the electrodes described have only volumetric capacities of less than 600 mAh / cm 3 , so that the desired increase in the
• the electrode coatings themselves are provided with a porosity.
• the pores are located between the constituents of the electrode coating, ie between the active material particles and the other electrode constituents.
• the active material particles themselves are generally largely non-porous.
• Such anode coatings are thus based on mere blends of active material particles, binders and other customary additives.
• Such coatings are also referred to as physical mixtures.
• US 2016006024 A describes negative electrodes based on non-graphitizable carbon-coated silicon-based active material and a non-fluorinated binder, wherein the electrode structure has a porosity of 30 to 80%.
• 3,039,152 B describes a negative electrode layer consisting of nanoparticles, which can consist of silicon or tin, for example, and which react with lithium in the form of an alloy formation and interpose matrix nanoparticles, such as cobalt oxide, which react with lithium in the form of a conversion reaction which have pores defining a total porosity of between 5 and 80%, preferably between 10 and 50%.
• US 2015228980 A describes a method for producing an electrode structure having a porosity of 20 to 80%, wherein the silicon-based active material particles are surface-functionalized and the functional groups are reacted with a suitable binder.
• the size of the silicon particles used is rich from 100 nm to 100 ⁇ , the particles are almost spherical with an aspect ratio of ⁇ 10.
• US Pat. No. 9012066 BB describes an electrode structure with a pore structure described by mercury porosimetry, wherein the distribution of the pore sizes against the mercury intrusion rate has pore sizes in the range from 30 to 10000 nm one or more maxima.
• active material silicon particles are used with a size of 0.5 to 20 ⁇ .
• the total porosity of the anode layer is in the range of 4 to 70%.
• the binder used is, in particular, crosslinked polyimide by heating, which leads to very low increases in the electrode thickness.
• the object of the present invention was to provide lithium-ion batteries with active material, such as silicon, tin or lead containing anodes, the highest possible volumetric capacity and after charging and discharging a stable electrochemical behavior with the least possible decrease have the reversible capacity (fading).
• active material such as silicon, tin or lead containing anodes
• this object has been achieved by providing the anode of the lithium-ion batteries with a well-defined porosity.
• An object of the invention are anodes of lithium-ion batteries,
• anodes comprise porous anode coatings with volumetric capacities of> 800 mAh / cm 3 and current collector and the porous anode coatings on at least one active material (AM) in the form of particles, one or more binders, optionally graphite, optionally one or more further electrically conductive components and optionally one or more additives,
• A active material
• the active material-containing particles to at least 90 wt .-%, based on the total weight of the active material-containing particles, made of an element selected from the group consisting of silicon (Si), tin (Sn) and lead (Pb), characterized in that
• porous anode coatings having a degree of lithiation in the range of 0.20 to 0.50
• porous anode coating having an active material content of 60 to 85% by weight, based on the total weight of the porous anode coating, have a porosity ⁇ in the range of 23 to 72% by volume; or d) porous anode coatings having a degree of lithiation ⁇ of 0.95 to 1.00 and
• porous anode coating having an active material content of 5 to 30% by weight, based on the total weight of the porous anode coating, have a porosity ⁇ in the range of 11 to 61% by volume.
• the porous anode coatings have a porosity ⁇ in the range of 6 to 61% by volume and preferably 7 to 56% by volume.
• the porous anode coatings having a degree of lithiation ⁇ from the range of 0.50 to ⁇ 1.00 and having an active material content of 5 to 20 wt .-%, based on the total weight of the porous anode coating, a porosity ⁇ in the range of preferably 6 to 48 vol .-% and particularly preferably 7 to 44 vol .-%.
• the porous anode coatings having a degree of lithiation ⁇ have a range from 0.50 to ⁇ 1.00 and an active material content of 20 to 30% by weight, based on the total weight of the porous anode coating, a porosity ⁇ in the range of preferably 20 to 61 vol .-% and particularly preferably 23 to 56 vol .-%.
• the porous anode coatings have a porosity ⁇ in the range of 19 to 71% by volume and preferably 21 to 66% by volume.
• the porous anode coatings having a degree of lithiation ⁇ have a range of from 0.30 to 0.70 and an active material content of from 30 to 45
• the porous anode coatings have a degree of lithiation in the range of 0.30 to 0.70 and an active material content of 45 to 60
• the porous anode coatings have a porosity ⁇ in the range of 23 to 72 vol .-% and preferably
• the porous anode coatings have a degree of lithiation in the range from 0.20 to 0.50 and with an active material content of 60 to 72
• a porosity ⁇ in the range of preferably 23 to 66 vol .-% and particularly preferably 26 to 61 vol .-%.
• the porous anode coatings have a degree of lithiation in the range of 0.20 to 0.50 and with an active material content of 72 to 85
• the porous anode coatings have a porosity ⁇ in the range of 11 to 61 vol .-%, and preferably 12 to 56 vol. -%.
• the porous anode coatings have a degree of lithiation in the range of 0.95 to 1.00 and with an active material content of 5 to 20 wt .-%, based on the total weight of the porous anode coating, a porosity ⁇ in the range of preferably 11 to 48 vol .-% and particularly preferably 12 to 44 vol .-%.
• the porous anode coatings having a degree of lithiation ⁇ have from the range of 0.95 to 1.00 and with an active material content of 20 to 30
• a porosity ⁇ in the range of preferably 32 to 61 vol .-% and particularly preferably 36 to 56 vol .-%.
• the porosity ⁇ of the porous anode coatings can be determined, for example, by means of Hg porosimetry (Porotec, Pascal 140/440) to DIN 66133.
• Hg porosimetry Porotec, Pascal 140/440
• a sample of the completely delithiated anode with a base area of 25 ⁇ 350 mm 2 is preferably used.
• Another object of the invention are anodes of lithium-ion batteries,
• anodes comprise porous anode coatings with volumetric capacities of 800 mAh / cm 3 and current collector and the porous anode coatings on at least one active material (AM) in the form of particles, one or more Bindinde, optionally graphite, optionally one or more further electrically conductive Components and optionally one or more additives,
• AM active material
• active material-containing particles to at least 90 Wt .-%, based on the total weight of the active material-containing particles, of an element selected from the group consisting of silicon (Si), tin (Sn) and lead (Pb) consist, characterized in that
• the porous anode coatings have a porosity ⁇ which is in the range of 0.9 * ⁇ f> 0p t ⁇ ⁇ ⁇ 1.3 * ⁇ opt, in which ⁇ ⁇ according to the following formula I
• c AM is the percentage by volume of unlithiated active material in the total volume of the unlithiated porous anode coating
• Another object of the invention are lithium-ion batteries containing the aforementioned anodes with inventive, porous anode coating.
• the porosity ⁇ generally assumes values greater than 0 and less than 75.
• 6 to 72% by volume is preferred, 7 to 66% by volume is particularly preferred, and 26 to 66% by volume is most preferred.
• the porosity ⁇ is in the range of 0.9 * ⁇ 0 ⁇ ⁇ 1.3 * ⁇ 0pt and preferably 1.0 * ⁇ 0pt ⁇ 1.2 * ⁇ 0 ⁇ .
• the symbol * in the formula I stands for the mathematical operator of multiplication.
• the parameter ⁇ represents the volume change of the active material as a result of the transition from the non-lithiated state to the state of complete lithiation.
• the parameter ⁇ is a material constant and is generally given for 20 ° C and atmospheric pressure.
• the degree of lithiation ⁇ expresses that the active material of the porous anode coating in the fully charged lithium-ion battery can be completely lithiated or partially lithiated.
• the active material of the porous anode coating is partially lithiated.
• unlithiated, delithiated and not lithiated are used interchangeably in the present specification.
• completely lithiated, fully lithiated and lithiated maximum are used interchangeably in the present specification.
• Fully charged indicates the state of the lithium-ion battery in which the porous anode coating of the lithium-ion battery has its highest lithium loading.
• Partial lithiation of the porous anode coating means that the maximum lithium uptake capacity of the active materials in the porous anode coating is not exhausted. In the case of partial lithiation, therefore, the capacity of the active material for lithium is not fully utilized.
• the maximum lithium absorption capacity of the silicon particles generally corresponds to the formula Li 4 . 4 Si and thus is generally 4.4 lithium atoms per silicon atom. This corresponds to a maximum specific capacity of 4200 mAh per gram of silicon.
• the maximum lithium uptake capacity generally corresponds to the formula Li 4 . 4 Sn and thus is generally 4.4 lithium atoms per tin atom. This corresponds to a maximum specific capacity of 993 mAh per gram of tin.
• the maximum lithium uptake capacity generally corresponds to the formula Li 4 , 5 Pb and is thus generally 4.5 lithium matome per lead atom. This corresponds to a maximum specific capacity of 582 mAh per gram of lead.
• the ratio of the lithium atoms to the active material atoms (AM) in the porous anode coating of a lithium-ion battery can be adjusted, for example, via the electric charge flow.
• the degree of lithiation of the porous anode coating or of the active material particles contained in the porous anode coating is proportional to the electric charge that has flowed.
• the capacity of the porous anode coating for lithium is not fully utilized. This results in partial lithiation of the anode.
• the Li / AM ratio of a lithium-ion battery is set by the cell balancing.
• the lithium-ion batteries are designed so that the lithium absorption capacity of the anode is preferably greater than the lithium emitting capacity of the cathode.
• the lithium uptake capability of the anode is not fully utilized, i. that the porous anode coating is only partially lithiated.
• the Li / AM ratio with partial lithiation of the porous anode coating in the fully charged state of the lithium ion battery is preferably 2,2 2.2, more preferably 1 1.98, and most preferably 1,7 1.76.
• the Li / AM ratio in the fully charged state porous anode coating of the lithium ion battery is preferably 0.22, more preferably 0.44, and most preferably 0.66.
• the capacity of the active material of the porous anode coating of the lithium-ion battery is preferably used at ⁇ 50%, more preferably at 45% and most preferably at 40%, based on the maximum capacity per gram of active material. rial.
• the maximum capacity per gram of silicon is 4200 mAh
• the maximum capacity per gram of tin is 993 mAh
• the maximum capacity per gram of lead is 582 mAh.
• the degree of lithiation ⁇ of the active material can be determined, for example, by the following formula III:
• ß area-related delithiation capacity of the active material-containing anode at the respective charge end voltage of the lithium-ion battery
• the lithium-ion battery is transferred to the electrically charged state by applying the constant current (CC) method with a constant current of 5 mA / g (equivalent to C / 25) until reaching the voltage limit of 4, 2V is charged.
• the anode is lithiated.
• the electrolyte used is a 1.0 molar solution of lithium hexafluorophosphate in a 3: 7 (v / v) mixture of fluoroethylene carbonate and ethyl methyl carbonate, which is mixed with 2.0% by weight of vinylene carbonate.
• the construction of the cell is generally carried out in a glove box ( ⁇ 1 ppm H 2 0 and 0 2 ).
• the water content of the dry matter of all starting materials is preferably below 20 ppm.
• the electrochemical measurements on full and half cells are carried out at 20 ° C.
• the above constant current refers to the weight of the positive electrode coating.
• the percentage volume fraction of the active material in the total volume of the porous anode coating (p M from formula I can be calculated using the following formula II
• P AM stands for the true density of the active material.
• the weight percentage m of the active material in the porous anode coating can be determined by first wet-digesting the porous anode coating and then by percent inductively coupled plasma (ICP) OES, the percent weight fraction Q m , as exemplified below for silicon described:
• the percent Si weight fraction ⁇ 3 ⁇ is determined by means of ICP-OES (inductively coupled plasma) emission spectrometry (measuring instrument: Optima 7300 DV, Fa, Perkin Elmer; sample introduction system: atomizer Meinhard with cyclone spray chamber; calibration range: 0.1 to 20.0 mg / 1 Si; standard Si stock Certipur from Merck with 1000 mg / 1 Si (certified)).
• ICP-OES inductively coupled plasma emission spectrometry
• the true density P A of the active material is a material constant.
• the pure density p m is generally: 2.3 g / cm 3 for silicon; 5.77 g / cm 3 for tin of the modification); 7.27 g / cm 3 for tin of modification ⁇ ); and 11.34 g / cm3 for lead.
• the density of the porous anode coating p B can be determined by first determining the weight of the porous anode coating gravimetrically and the thickness of the porous anode coating with the measuring instrument Mitutoyo (1 ⁇ m to 12.7 mm) with precision measuring table. The density of the porous anode coating p B is then obtained by dividing the weight of the porous anode coating by the thickness of the porous anode coating.
• the stated values for the porosity and also formula I generally relate to electrolyte-free or substantially electrolyte-free porous anode coatings in the delithiated state.
• the porous anode coatings with silicon as active material have a density (p B ) of preferably 0.92 to 2.31 g / cm 3 and more preferably 0.99 to 2.08 g / cm 3 .
• the porous anode coatings with silicon as the active material have a density (p B ) of preferably
• the porous anode coatings have Silicon as the active material has a density (p B ) of preferably 0.92 to 1.92 g / cm 3 and particularly preferably 0.99 to 1.73 g / cm 3 .
• the porous anode coatings with silicon as the active material have a density (p B ) of preferably
• the porous anode coatings with silicon as active material have a density (p B ) of preferably 0.89 to 1.96 g / cm 3 and more preferably 0.97 to 1.77 g / cm 3 .
• the porous anode coatings with silicon as the active material have a density (p B ) of preferably from 0.77 to 1.78 g / cm 3, and more preferably from 0.84 to 1.60 g / cm 3 .
• the porous anode coatings with silicon as the active material have a density (p B ) of preferably 0.77 to 1.84 g / cm 3, and more preferably 0.83 to 1.65 g / cm 3 .
• the porous anode coatings with silicon as the active material have a density (p B ) of preferably
• the porous anode coatings with silicon as the active material have a density (p B ) of preferably 0.77 to 1.75 g / cm 3 and more preferably 0.83 to 1.57 g / cm 3 .
• the porous anode coatings with silicon as the active material have a density (p B ) of preferably 0.92 to 2.18 g / cm 3 , particularly preferably 0.99 to 1.96 g / cm 3 .
• the porous anode coatings with silicon as the active material have a density (p B ) of preferably from 1.08 to 2.18 g / cm 3 , more preferably from 1.17 to 1.96 g / cm 3 .
• the porous anode coatings with silicon as the active material have a density (p B ) of preferably 0.92 to 1.60 g / cm 3 , particularly preferably 0.99 to 1.44 g / cm 3 .
• the volumetric capacity of the porous anode coatings is accessible by the use of the above-described chen-related delithiation capacity ß divided by the thickness of the porous anode coating.
• the thickness of the porous anode coating can be determined with the measuring instrument digital gauge Mitutoyo (1 ⁇ im to 12.7 mm) with precision measuring table.
• the volumetric capacity is preferably 900 mAh / cm 3 , more preferably 1000 1000 mAh / cm 3, and most preferably 11 1100 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably at least 800 to 1986 mAh / cm 3 and more preferably 850 to 1788 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably 800 to 1752 mAh / cm 3, and more preferably 850 to 1577 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably 928 to 1986 mAh / cm 3, and more preferably 1006 to 1788 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably at least 842 to 2112 mAh / cm 3, and more preferably 912 to 1901 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably from 842 to 1950 mAh / cm 3 and particularly preferably from 912 to 1755 mAh / cm 3.
• the porous anode coatings have a volumetric capacity of preferably 927 to 2112 mAh / cm 3, and more preferably 1004 to 1901 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably at least 806 to 2018 mAh / cm 3, and more preferably 873 to 1817 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably 806 to 1933 mAh / cm 3, and more preferably 873 to 1740 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably 834 to 2018 mAh / cm 3, and more preferably 904 to 1817 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably at least 805 to 1986 mAh / cm 3, and more preferably 872 to 1788 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably 805 to 1752 mAh / cm 3, and more preferably 872 to 1577 mAh / cm 3 .
• the porous anode coatings have a volumetric capacity of preferably 1189 to 1986 mAh / cm 3, and more preferably 1288 to 1788 mAh / cm 3 .
• the active material-containing particles are preferably at least 95 wt .-% and particularly preferably at least 97 wt .-%, based on the total weight of the active material-containing particles, of an element selected from the group comprising silicon (Si), tin (Sn) and Lead (Pb). Most preferably, the active material-containing particles consist exclusively of active material.
• the active material-containing particles are preferably not porous composites.
• active materials are usually incorporated into a matrix.
• the matrix can be based on carbon, for example.
• the matrix generally contains pores intended to at least partially accommodate the volume changes of the active material upon incorporation of lithium.
• the matrix may additionally be coated, for example with carbon or polymers.
• Preferred active material is silicon.
• the anode coatings preferably contain silicon particles.
• the volume-weighted particle size distribution of the silicon particles is preferably between the diameter percentiles of ⁇ 0.2 pm and d 90 20 20.0 pm, more preferably between 0 0 0,2 0.2 pm and d 90 10 10.0 pm, and most preferably between di 0 ⁇ 0.2 pm to d 90 ⁇ 5.0 pm.
• the silicon particles have a volume weighted particle size distribution with diameter percentiles preferably ⁇ 10 pm, more preferably> 5 pm, even more preferably> 3 pm and most preferably ⁇ 1 pm.
• the silicon particles have a volume-weighted particle size distribution with diameter percentiles d 90 of preferably.
• the aforementioned d 90 - ert is preferably 5 pm.
• the volume-weighted particle size distribution of the silicon particles has a width d 90 -di 0 of preferably -S 15.0 pm, more preferably ⁇ 12.0 pm, even more preferably ⁇ 10.0 pm, more preferably ⁇ 8.0 pm and am most preferably ⁇ 4.0 pm.
• the volume-weighted particle size distribution of the silicon particles has a width d 90 -di 0 of preferably 0,6 0.6 ⁇ m, more preferably 0,8 0.8 ⁇ m, and most preferably 1,0 1.0 ⁇ m.
• the volume-weighted particle size distribution of the silicon particles has diameter percentiles d 50 of preferably 0.5 to 10.0 ⁇ m, more preferably 0.6 to 7.0 ⁇ m, even more preferably 2.0 to 6.0 ⁇ m, and most preferably 0.7 to 3.0 pm.
• Twice to five times, in particular two to three times the aforementioned d 50 values is preferably smaller than the layer thickness of the anode coating.
• the layer thickness of the anode coating is given below. This proviso is helpful in virtually eliminating oversize grain.
• the volume-weighted particle size distribution of the silicon particles can be determined by static laser scattering using the Mie model with the Horiba LA 950 measuring instrument with ethanol as the dispersing medium for the silicon particles.
• the volume-weighted particle size distribution of the silicon particles is preferably monomodal.
• the volume-weighted particle size distribution of the silicon particles is generally narrow, as can be seen from the d 10 or d 90 values and d 90 -d 10 values.
• the silicon particles are preferably not aggregated, particularly preferably not agglomerated and / or not nanostructured.
• Aggregated means that spherical or largely spherical primary particles, such as those initially formed in gas phase processes during the production of the silicon particles, grow together in the further course of the gas phase process to form aggregates. These aggregates can form agglomerates in the further course of the reaction. Agglomerates are a loose aggregate of aggregates. Agglomerates can be easily split again into the aggregates using typically used kneading and dispersing processes. Aggregates can not be decomposed with these methods or only to a small extent into the primary particles.
• Non-nanostructured silicon particles generally have characteristic BET surfaces.
• the BET surface areas of the silicon particles are preferably 0.01 to 30.0 m 2 / g, more preferably 0.1 to 25.0 m 2 / g, particularly preferably 0.2 to 20.0 m 2 / g and most preferably 0.2 to 18.0 m 2 / g.
• the BET surface area is determined according to DIN 66131 (with nitrogen).
• the silicon particles have a sphericity of preferably 0.3 ⁇ 0.9, more preferably 0.5 ⁇ 0.85 and most commonly preferably 0.65 ⁇ ⁇ 0.85. Silicon particles having such sphericities become accessible in particular by production by means of milling processes.
• the sphericity ⁇ is the ratio of the surface of a sphere of equal volume to the actual surface of a body (definition of adell). Sphericities can be determined, for example, from conventional REM images.
• the silicon particles may consist of elemental silicon, a silicon oxide or a binary, ternary or multinary silicon / metal alloy (with, for example, Li, Na, K, Sn, Ca, Co, Ni, Cu, Cr, Ti, Al, Fe) exist. Preference is given to using elemental silicon, in particular since this has an advantageously high storage capacity for lithium ions.
• under elemental silicon is highly pure polysilicon, with a low proportion of impurities (such as B, P, As), specifically doped with impurity silicon (such as B, P, As), but also metallurgical silicon, which elemental contamination (such as Fe, Al, Ca, Cu, Zr, C).
• impurities such as B, P, As
• impurity silicon such as B, P, As
• metallurgical silicon which elemental contamination (such as Fe, Al, Ca, Cu, Zr, C).
• the stoichiometry of the oxide SiO x is preferably in the range 0 ⁇ x ⁇ 1.3. If the silicon particles contain a silicon oxide with a higher stoichiometry, then its layer thickness on the surface is preferably less than 10 nm.
• the surface of the silicon particles may optionally be covered by an oxide layer or by other inorganic and organic groups.
• Particularly preferred silicon particles carry on the surface Si-OH or Si-H groups or covalently attached organic groups, such as alkoxy or alkyl groups.
• the organic groups can be used, for example, to control the surface tension of the silicon particles and, in particular, to control the solvents or binders. be adjusted if necessary, which are used in the production of anode coatings.
• the proportion of active material, in particular the silicon content, in a porous anode coating is preferably between 40% by weight and 95% by weight, more preferably between 50% by weight and 90% by weight and most preferably between 60% by weight. and 85% by weight based on the total weight of the porous anode coating.
• the silicon particles can be produced, for example, by milling processes.
• silicon particles having the preferred properties are obtainable, for example with advantageous sphericity, such as fracture surfaces which are advantageous in the application, in particular sharp-edged fracture surfaces, or, for example, splinter-shaped silicon particles.
• the particle size distributions of the silicon particles which are essential to the invention and non-aggregated silicon particles are also very easily accessible by milling processes.
• milling processes for example, dry or wet grinding processes come into consideration.
• jet mills such as counter-jet or impact mills, or stirred ball mills are used.
• the grinding in the jet mill is preferably carried out with nitrogen or noble gases, preferably argon, as the grinding gas.
• the jet mills preferably have an integrated air classifier, which may be static or dynamic, or they are operated in the circuit with an external air classifier.
• one or more organic or inorganic liquids or liquid mixtures may be used.
• such liquids or liquid mixtures at room temperature have a viscosity of preferably below 100 mPas and in particular ders preferred below 10 mPas.
• the liquids or liquid mixtures are inert or slightly reactive towards silicon.
• the liquid is particularly preferably organic and contains less than 5% by weight of water, more preferably less than 1% by weight of water.
• organic liquids hydrocarbons, esters or, in particular, alcohols are preferred.
• the alcohols preferably contain 1 to 7 and more preferably 2 to 5 carbon atoms. Examples of alcohols are methanol, ethanol, propanol and butanol.
• Hydrocarbons preferably contain 5 to 10 and more preferably 6 to 8 carbon atoms. Hydrocarbons may be, for example, aliphatic or aromatic. Examples of hydrocarbons are toluene and heptane. Esters are generally esters of carboxylic acids and alkyl alcohols, such as ethyl acetate.
• the porous anode coatings are preferably based on a mixture comprising at least one active material in the form of particles, in particular silicon particles, one or more binders, optionally graphite, optionally one or more further electrically conductive components and optionally one or more additives.
• the further electrically conductive components in the porous anode coatings can reduce the contact resistances within a porous anode coating and between porous anode coating and current collector, which improves the current-carrying capacity of the lithium-ion battery.
• Preferred further electrically conductive components are conductive black, Carbon nanotube or metallic particles, for example copper.
• a porous anode coating preferably contains 0 to 40 wt%, more preferably 0 to 30 wt%, and most preferably 0 to 20 wt% of one or more other electrically conductive components, based on the total weight of the porous anode coating.
• Preferred binders are polyacrylic acid or its alkali metal salts, in particular lithium or sodium salts, polyvinyl alcohols, cellulose or cellulose derivatives, polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, polyimides, in particular polyamido-imides, or thermoplastic elastomers, in particular ethylene-propylene-diene Terpolymers.
• polyacrylic acid polymethacrylic acid or cellulose derivatives, in particular carboxymethylcellulose.
• alkali especially lithium or sodium salts
• the alkali salts especially lithium or sodium salts, polyacrylic acid or polymethacrylic acid. It may be present all or preferably a portion of the acid groups of a binder in the form of salts.
• the binders have a molecular weight of preferably 100,000 to 1,000,000 g / mol. It is also possible to use mixtures of two or more binders.
• graphite generally natural or synthetic graphite can be used.
• the graphite particles preferably have a volume-weighted particle size distribution between the diameter percentiles di 0 > 0.2 pm and d 90 ⁇ 200 ⁇ .
• additives are pore formers, dispersants, leveling agents or dopants, for example elemental lithium.
• Preferred formulations for the production of porous anode coatings contain preferably 5 to 95% by weight, preferably 60 to 85% by weight, of active material, in particular siliconpar- Tikel; 0 to 40 wt .-%, in particular 0 to 20 wt .-% further electrically conductive components; 0 to 80 wt .-%, in particular 5 to 30 wt .-% graphite; 0 to 25% by weight, in particular 5 to 15% by weight, of binder; and optionally 0 to 80 wt .-%, in particular 0.1 to 5 wt .-% additives; where the data in% by weight relate to the total weight of the formulation and the proportions of all constituents of the formulation add up to 100% by weight.
• the proportion of graphite particles and further electrically conductive components is at least 10% by weight, based on the total weight of the formulation.
• the processing of the constituents of the formulation into an anode ink or paste can be carried out, for example, in a solvent such as water, hexane, toluene, tetrahydrofuran, N-methylpyrrolidone, N-ethylpyrrolidone, acetone, ethyl acetate, dimethyl sulfoxide, dimethylacetamide or ethanol, or solvent mixtures
• a solvent such as water, hexane, toluene, tetrahydrofuran, N-methylpyrrolidone, N-ethylpyrrolidone, acetone, ethyl acetate, dimethyl sulfoxide, dimethylacetamide or ethanol, or solvent mixtures
• rotor-stator machines high energy mills, planetary kneaders,
• the anode ink or paste has a pH of preferably 2 to 7.5 (determined at 20 ° C, for example with the pH meter of WTW pH 3 Oi with probe SenTix RJD).
• the anode ink or paste may be strung on a copper foil or other current collector.
• Other coating methods such as e.g. Spin-coating, roller, dip or slot die coating, brushing or spraying can also be used.
• the coatings thus obtained can be dried at room temperature or preferably at elevated temperature.
• the drying temperature depends, as usual, on the components used and the solvent used.
• the drying temperature is preferably between 20 ° C and 300 ° C, more preferably between 50 ° C and 180 ° C.
• the drying temperature should preferably be lower than the glass transition temperature or the pour point of constituents of the anode coating.
• the drying may be carried out under reduced pressure or, preferably, at ambient pressure. Common devices can be used, such as belt dryers, suspended dryers, air flow dryers, such as hot gas dryers or hot gas dryers, or IR dryers.
• the drying can thus be done in a conventional manner. Generally it is dried to constant weight.
• the coatings thus obtained can be further treated. This may be useful for obtaining the porosity ⁇ according to the invention or for other purposes.
• the coatings can be compacted.
• known devices and methods can be used, such as calendering or pressing.
• the compression can be carried out at room temperature or at elevated temperatures.
• the selected temperature should preferably be lower than the glass transition temperature or the pour point of constituents of the anode coating.
• the layer thickness that is to say the dry layer thickness of the porous anode coating, is preferably 2 .mu.m to 500 .mu.m, more preferably from 10 .mu.m to 300 .mu.m.
• a lithium-ion battery generally comprises a first electrode as a cathode, a second electrode as an anode, a membrane arranged as a separator between the two electrodes, two electrically conductive connections on the electrodes, a housing accommodating said parts and an electrolyte containing lithium ions, with which the separator and the two electrodes are impregnated, wherein a part of the second electrode is the anode according to the invention containing the porous anode coating.
• Anodes according to the invention can be processed with other conventional materials and materials by known methods into lithium-ion batteries, analogously as described, for example, in WO 2015/117838.
• lithium-ion batteries with active material such as tin, lead and in particular
• the lithium-ion batteries according to the invention are thus characterized by advantageous cycle behavior and at the same time by high volumetric energy densities.
• the silicon powder was prepared according to the prior art by grinding a coarse Si-split from the production of solar silicon in a fluidized-bed jet mill (Netzsch-Condux CGS16 with 90 m 3 / h of nitrogen at 7 bar as milling gas).
• the dispersion was applied to a 0.030 mm thick copper foil (Schlenk Metallfolien, SE-Cu58) by means of a film drawing frame with 0.10 mm gap height (Erichsen, Model 360).
• the anode coating thus prepared was then dried for 60 minutes at 80 ° C and 1 bar air pressure.
• the dried anode coating had an average basis weight of 2.90 mg / cm 2 and a layer thickness of 32 ⁇ .
• Table 1 Anode coatings of (comparative) Examples 2a, 2b and 2c:
• Porosity ⁇ range of 31.2 to 45.1%
• Porosity ⁇ range of 43.6 to 62.9%.
• the anode 2a is thus according to the invention, while the anodes 2b and 2c are not.
• Lithium-ion battery with the anode of Example 2a Lithium-ion battery with the anode of Example 2a:
• the electrolyte used consisted of a 1, 0 molar solution of lithium hexafluorophosphate in a 3: 7 (v / v) mixture of fluoroethylene carbonate and ethyl methyl carbonate, which was mixed with 2.0 wt .-% vinylene carbonate.
• the construction of the cell took place in a glove box ( ⁇ 1 ppm H 2 0, 0 2 ), the water content in the dry matter of all components used was below 20 ppm.
• the electrochemical testing was carried out at 20 ° C.
• the cell was charged in constant current / constant voltage (cc / cv) mode with a constant current of 5 mA / g (C / 25) in the first cycle and 60 mA / g (C / 2) in the following Cycles and after reaching the voltage limit of 4.2 V with constant voltage to below a current of 1.2 mA / g (corresponds to C / 100) or 15 mA / g (corresponds to C / 8).
• cc / cv constant current / constant voltage
• the cell was discharged in the cc (constant current) method with a constant current of 5 mA / g (equivalent to C / 25) in the first cycle and 60 mA / g (equivalent to C / 2) in the subsequent cycles until reaching the voltage limit of 3.0 V.
• the selected specific current was based on the weight of the positive electrode coating.
• the lithium ion battery was operated by cell balancing with partial lithiation of the anode.
• Fig. 1 shows the discharge capacity of a full cell based on the anode coating of Example 2a as a function of the number of cycles.
• the full cell has a reversible capacity of 2.21 mAh / cm 2 in the first cycle (C / 25).
• the area-related delithiation capacity ⁇ is 2.46 mAh / cm 2 , the degree of lithiation ⁇ is 28.8%, the volumetric anodization the capacity is 1116 mAh / cra 3 .
• the area-related delithiation capacity ⁇ , the degree of lithiation ⁇ and the volumetric anode capacity were determined according to the methods given above in the general description.
• Example 3 had a high volumetric capacity and showed little fading.
• Lithium-ion battery with the anode of example 2b Lithium-ion battery with the anode of example 2b:
• Example 2b The anode of Example 2b was tested as described in Example 3.
• Fig. 2 shows the discharge capacity of a full cell on the basis of the anode coating of Example 2b as a function of Zyk ⁇ leniere.
• the full cell has in the first cycle (C / 25) has a reversible capacity Capa ⁇ of 2.19 mAh / cm 2.
• the area-related delithiation capacity ⁇ is 2.43 mAh / cm 2 , the degree of lithiation ⁇ is 28.5%, and the volumetric anode capacity is 759 mAh / cm 3 .
• Lithium-ion battery with the anode of example 2c Lithium-ion battery with the anode of example 2c:
• Example 2c The anode of Example 2c was tested as described in Example 3.
• Fig. 3 shows the discharge capacity of a full cell based on the anode coating of Example 2c as a function of the number of cycles.
• the full cell has a reversible capacity of 2.25 mAh / cm 2 in the first cycle (C / 25).
• the area-related delithiation capacity ⁇ is 2.50 mAh / cm 2 , the degree of lithiation a 29.3%, the volumetric anode capacity 1561 mAh / cm 3 .
• Comparative Example 5 Although the full cell of Comparative Example 5 had a high volumetric capacity, it disadvantageously exhibited high fading.
• Table 2 summarizes the results of examinations of Example 3 and Comparative Examples 4 and 5.
• the lithium ion battery of Example 3 surprisingly exhibits both a very high volumetric anode capacity (cycle 1) and a more stable electrochemical behavior in the subsequent cycles compared to the lithium ion batteries of comparative examples 4 and 5.

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• 2016
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