EP3507844A1

EP3507844A1 - Anodes of lithium ion batteries

Info

Publication number: EP3507844A1
Application number: EP16758165.1A
Authority: EP
Inventors: Jürgen Pfeiffer; Stefan Haufe
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 2016-08-30
Filing date: 2016-08-30
Publication date: 2019-07-10
Also published as: WO2018041339A1; CN109643789B; CN109643789A; KR20190042700A; KR102240050B1

Abstract

The invention relates to anodes of lithium ion batteries, the anodes comprising porous anode coatings with volumetric capacities of ≥ 800 mAh/cm³ and current collectors, the porous anode coatings being based on at least one active material (AM) in the form of particles, at least one binder, optionally graphite, optionally at least one other electroconductive component and optionally at least one additive, where the particles containing active material consist of at least 90 wt. %, in relation to the total weight of the particles containing active material, of an element selected from the group comprising silicon (Si), tin (Sn) and lead (Pb), characterised in that the porous anode coatings have a porosity φ in the region of 0.9 * Φ_Opt ≤ Φ φ_ΑΜ1.3 * Φ_Opt, in which Φ_Opt is determined according to the following formula I Φ_Opt = φ_ΑΜ * α * K (I), where φ_ΑΜ is the volume percent of the non-lithiated active material in relation to the total volume of the non-lithiated porous anode coating, α is the lithiation degree of the active material in the porous anode coating and can have values of 0 < α ≤ 1, and K represents the value of 3.00 for silicon, 2.44 for tin, and 2.22 for lead.

Description

Anodes of lithium-ion batteries

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. In 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. For this purpose, 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.

However, 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. In order to increase the electrochemical capacities of lithium-ion batteries, 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. This ultimately results in a further decrease in their capacity after each charging or discharging operation of the lithium-ion battery, which is also referred to as a decrease in the reversible capacity (fading).

In order to protect lithium-ion batteries from such damage, 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. However, 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 best graphite-based anodes of high-energy lithium-ion batteries today have volumetric electrode capacitances of 600 to 650 mAh / cm ³ . US2011183209 teaches high ionic density ionic ion anodes coatings with low porosities, for example 15%. Due to the high densification and the resulting low porosity, however, there are limitations with regard to the possible rate of introduction and removal of the lithium ions.

Against this background, there is a challenge to provide porous, silicon-containing anodes for lithium-ion batteries, which have the highest possible volumetric capacity and also suffer the least possible fading.

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. However, the production of such composites is complicated. In addition, it is a challenge to introduce the pores in the targeted places and in the expansion in the composite that the volume changes of each active material particle are completely absorbed. 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%. In addition, a carbon layer can be applied to the surface.

In another approach, 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

Energy density compared to established graphite-containing cells is not achieved. In addition, the improvement in cycle life of the battery described therein does not yet meet current practical requirements.

In another alternative approach for buffering the active material volume expansion, the electrode coatings themselves are provided with a porosity. In such porous electrode structures, 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%. US Pat. No. 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 μιη, 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. As active material silicon particles are used with a size of 0.5 to 20 μτη. 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. Thus, when using 5 μπι silicon particles in admixture with a polyimide as a binder (80/20 wt / wt) and a porosity of the electrode of 20% according to the invention a loss of 15% of the capacity after the hundredth cycle after the formation achieved. Although this represents a significant improvement compared to the comparative examples not according to the invention, it is by far not sufficient for technical applications, such as in electric vehicles. The importance of the volumetric capacity of the negative electrode layer for the achievable energy density of a lithium-ion cell is not discussed. Despite the improvements achieved by providing porosity in particular in O2016 / 092335 and in US9012066 B, it can thus be stated that satisfactory cycle strengths could not be achieved with sufficiently high volumetric electrode capacities at the same time to increase the cell energy density.

Against this background, 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). Surprisingly, 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,

wherein the 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,

wherein 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

a) porous anode coatings with a degree of lithiation α in the range of 0.50 to <1.00 and

having an active material content of 5 to 30% by weight, based on the total weight of the porous anode coating, have a porosity φ in the range of 6 to 61% by volume; or

b) porous anode coatings with a degree of lithiation α in the range of 0.30 to 0.70 and

having an active material content of 30 to 60% by weight, based on the total weight of the porous anode coating, have a porosity φ in the range of 19 to 71% by volume; or

c) porous anode coatings having a degree of lithiation in the range of 0.20 to 0.50 and

having an active material content of 60 to 85% by weight, based on the total weight of the porous anode coating, have a porosity φ in the range of 23 to 72% by volume; or d) porous anode coatings having a degree of lithiation α of 0.95 to 1.00 and

having an active material content of 5 to 30% by weight, based on the total weight of the porous anode coating, have a porosity φ in the range of 11 to 61% by volume.

In alternative a), the porous anode coatings have a porosity φ in the range of 6 to 61% by volume and preferably 7 to 56% by volume.

In a further alternative al), a preferred embodiment of alternative a), the porous anode coatings having a degree of lithiation α 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 φ in the range of preferably 6 to 48 vol .-% and particularly preferably 7 to 44 vol .-%.

In a further alternative a2), a preferred embodiment of alternative a), the porous anode coatings having a degree of lithiation α 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 φ in the range of preferably 20 to 61 vol .-% and particularly preferably 23 to 56 vol .-%.

In alternative b), the porous anode coatings have a porosity φ in the range of 19 to 71% by volume and preferably 21 to 66% by volume.

In a further alternative b1), a preferred embodiment of alternative b), the porous anode coatings having a degree of lithiation α have a range of from 0.30 to 0.70 and an active material content of from 30 to 45

Wt .-, based on the total weight of the porous anode coating, a porosity φ in the range of preferably 19 to 62 vol .-% and particularly preferably 21 to 57 vol .-%. In a further alternative b2), a preferred embodiment of alternative b), 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

Wt .-%, based on the total weight of the porous anode coating, a porosity φ in the range of preferably

25 to 71% by volume and more preferably 28 to 66% by volume.

In alternative c), the porous anode coatings have a porosity φ in the range of 23 to 72 vol .-% and preferably

26 to 66% by volume.

In a further alternative c1), a preferred embodiment of alternative c), 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

Wt .-%, based on the total weight of the porous anode coating, a porosity φ in the range of preferably 23 to 66 vol .-% and particularly preferably 26 to 61 vol .-%.

In a further alternative c2), a preferred embodiment of alternative c), 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

From 27 to 72% by volume and more preferably from 30 to 66% by volume.

In alternative d), the porous anode coatings have a porosity φ in the range of 11 to 61 vol .-%, and preferably 12 to 56 vol. -%.

In a further alternative d1), a preferred embodiment of alternative d), 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 φ in the range of preferably 11 to 48 vol .-% and particularly preferably 12 to 44 vol .-%.

In a further alternative d2), a preferred embodiment of alternative d), the porous anode coatings having a degree of lithiation α have from the range of 0.95 to 1.00 and with an active material content of 20 to 30

Wt .-%, based on the total weight of the porous anode coating, a porosity φ in the range of preferably 32 to 61 vol .-% and particularly preferably 36 to 56 vol .-%.

Preferred are the alternative c), in particular the alternatives cl) and c2). The porosity φ of the porous anode coatings can be determined, for example, by means of Hg porosimetry (Porotec, Pascal 140/440) to DIN 66133. For this purpose, a sample of the completely delithiated anode with a base area of 25 × 350 mm ² is preferably used.

Further information on the volumetric capacity parameters, the degree of lithiation a and the porosity φ can be found below. The novel anodes of lithium-ion batteries with the porous anode coatings according to the alternatives a) to d) can be summarized by the following formula I.

Another object of the invention are anodes of lithium-ion batteries,

wherein the 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,

wherein the 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 φ which is in the range of 0.9 * <f> _0p t ^ ψ ^ 1.3 * φ opt, in which φ <^ according to the following formula I

φορ = ΑΜ * * K (I) determines where

c AM is the percentage by volume of unlithiated active material in the total volume of the unlithiated porous anode coating,

represents the degree of lithiation of the active material in the porous anode coating and can assume values of 0 <α <1 and

K for silicon (Si) the value of 3.00, for tin (Sn) the value of 2.44 and for lead (Pb) the value of 2.22 and.

Another object of the invention are lithium-ion batteries containing the aforementioned anodes with inventive, porous anode coating.

The porosity φ generally assumes values greater than 0 and less than 75. For the porosity φ, 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 φ is in the range of 0.9 * φ _0ρί <φ 1.3 * § _0pt and preferably 1.0 * § _0pt <φ 1.2 * φ _0ρί . The symbol * in the formula I stands for the mathematical operator of multiplication.

The parameter κ 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 κ is generally given by the difference between the volume of the fully lithiated active material (Vii _th .) And the volume of unlithiierten active material (V _un ii _t .) By the volume of unlithiier- active material (V _un i _lth ,) is divided; or expressed mathematically by the following equation: κ = (Vi _it h - _unlith V..) / V i _un _ith. The parameter κ is a material constant and is generally given for 20 ° C and atmospheric pressure.

The degree of lithiation α expresses that the active material of the porous anode coating in the fully charged lithium-ion battery can be completely lithiated or partially lithiated. For fully lithiated active material = 1, for unlithiated active material = 0, and for partially lithiated active material, 0 <<1. Preferably, the active material of the porous anode coating is partially lithiated. The terms unlithiated, delithiated and not lithiated are used interchangeably in the present specification. The terms 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. In the case of the tin particles, 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. In the case of the lead particles, 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 (Li / AM ratio) 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. In this variant, when charging the lithium-ion battery, the capacity of the porous anode coating for lithium is not fully utilized. This results in partial lithiation of the anode.

In an alternative, preferred variant, the Li / AM ratio of a lithium-ion battery is set by the cell balancing. Here, 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. As a result, in the fully charged battery, the lithium uptake capability of the anode is not fully utilized, i. that the porous anode coating is only partially lithiated.

In a preferred embodiment, 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, and the maximum capacity per gram of lead is 582 mAh. The degree of lithiation α of the active material can be determined, for example, by the following formula III:

SS 100

= - III, with

y-FG- <u _AM

ß: area-related delithiation capacity of the active material-containing anode at the respective charge end voltage of the lithium-ion battery;

γ: maximum capacity of the active material for lithium

(corresponds to 4200 mAh / g for silicon at a stoichiometry of Li _{/ 4} Si,

for tin at a stoichiometry of Li ₄ . ₄ Sn 993 mAh / g and for lead at a stoichiometry of Li ₄ . ₅ Pb 582 mAh / g);

FG: basis weight of the anode coating;

<x> _m % active material weight percentage in the anode coating. Determination of area-related delithiation capacity ß:

First, 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. In this case, the anode is lithiated. The thus charged lithium-ion battery is opened, removed the anode and built with this a button half-cell (type CR2032, Hohsen Corp.) with lithium counter electrode (Rockwood Lithium, thickness 0.5 mm, diameter = 15 mm). A glass fiber filter paper impregnated with 120 μΐ electrolyte (Whatman, GD Type D) can serve as a separator (diameter = 16 mm). 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 flax particle-related delithiation capacity β of the active material-containing anode coating is determined by charging the button half cell (working electrode = positive electrode = active material anode, counter electrode = anode = lithium) with C / 25 until the voltage limit of 1 is reached, 5 V. 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

ΦΑΜ = AM AM * PB / PAM (II), wherein is the percentage by weight of the active material in the porous anode coating,

p _B for the density of the porous anode coating and

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:

From a sample of completely delithiated porous anode coating (without current collector, such as Cu foil) is first washed out electrolyte with tetrahydrofuran. The sample is then acidified. For this purpose, 75 mg of the thus treated anode coating are transferred to a microwave digestion vessel (100 ml TFM liner from Anton Paar) and admixed with 5 ml HNO ₃ (65% strength, pa), 0.25 ml HCl (37% strength, pa ) and 1 ml HF (40%, suprapur). The microwave digestion vessel is capped, placed in a microwave oven (Multiwave 3000 Anton Paar) and treated for 45 min at 950W. The digestion is transferred completely into 50 ml tubes and made up to 50 ml with water. Of these, 0.50 ml are removed, mixed with 2.50 ml of 4% boric acid and made up to 50 ml again (dilution: Factor 100}. The percent Si weight fraction ω ₃ ι 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)).

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 β); 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 μm 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.

In the following, areas for the densities p _B are given by way of example for the active material silicon. In alternative a), 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 .

In alternative al), the porous anode coatings with silicon as the active material have a density (p _B ) of preferably

1.08 to 2.31 g / cm ^3, and more preferably 1.17 to 2.08 g / cm ³ . In alternative a2), 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 .

In alternative b), the porous anode coatings with silicon as the active material have a density (p _B ) of preferably

0.77 to 1.96 g / cm ³ and more preferably 0.84 to 1.77 g / cm ³ .

In alternative b1), 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 . In alternative b2), 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 . In alternative c), 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 .

In alternative cl), the porous anode coatings with silicon as the active material have a density (p _B ) of preferably

0.84 to 1.84 g / cm ^3, and more preferably 0.91 to 1.65 g / cm ³ . In alternative c2), 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 .

In alternative d), 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 . In alternative dl), 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 . In alternative d2), 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 . In alternative a) 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 .

In alternative al), 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 . In alternative a2), 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 .

In alternative b), 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 . In alternative bl), 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. In alternative b2), 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 .

In alternative c), 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 .

In alternative cl), 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 . In alternative c2), 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 .

In alternative d), 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 .

In alternative dl), 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 . In alternative d2), 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. In 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.

Below, by way of example, further parameters, such as particle size distributions, are given for the active material silicon. 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.

0.5 pm. In one embodiment of the present invention, 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 μm, more preferably 0,8 0.8 μm, and most preferably 1,0 1.0 μm.

The volume-weighted particle size distribution of the silicon particles has diameter percentiles d ₅₀ of preferably 0.5 to 10.0 μm, more preferably 0.6 to 7.0 μm, even more preferably 2.0 to 6.0 μm, 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. Due to their formation, aggregates and agglomerates inevitably have completely different spheres and grain shapes than the preferred silicon particles. The presence of silicon particles in the form of aggregates or agglomerates can be made visible for example by means of conventional scanning electron microscopy (SEM). By contrast, static light scattering methods for determining the particle size distributions or particle diameters of silicon particles can not distinguish between aggregates or agglomerates. 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 <ψ <0.85. Silicon particles having such sphericities become accessible in particular by production by means of milling processes. The sphericity ψ 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).

If the silicon particles contain a silicon oxide, then 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. By grinding 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.

As milling processes, for example, dry or wet grinding processes come into consideration. In this case, preferably planetary ball mills, 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.

For milling to produce the silicon particles in suspension, one or more organic or inorganic liquids or liquid mixtures may be used. Preferably, such liquids or liquid mixtures at room temperature have a viscosity of preferably below 100 mPas and in particular ders preferred below 10 mPas. Preferably, 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. As 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. Preferred are ethanol and 2-propanol. 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.

In the preparation of the silicon particles by Na milling in a suspension grinding media are preferably used whose average diameter is 10 to 1000 times greater than the d ₉₀ value of the distribution of the millbase used. Particularly preferred are grinding media whose average diameter is 20 to 200 times greater than the d ₉₀ value of the initial distribution of the millbase. 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. Particularly preferred are polyacrylic acid, polymethacrylic acid or cellulose derivatives, in particular carboxymethylcellulose. Particular preference is also the alkali, especially lithium or sodium salts, the aforementioned binder. Most preferred are 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.

As 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 μτη.

Examples of 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. In a preferred formulation for producing the porous anode coatings, 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 Preferably using rotor-stator machines, high energy mills, planetary kneaders, agitator ball mills, vibrating plates or ultrasonic devices.

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).

For example, 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.

Lower solvent or high solids content anode inks or pastes generally result in lower porosity coatings; a higher content of solvents or a low solids content generally leads to a higher porosity.

The coatings thus obtained can be further treated. This may be useful for obtaining the porosity φ according to the invention or for other purposes. For example, the coatings can be compacted. For this purpose, 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 person skilled in the art can determine the conditions for the drying and the possible compacting by means of less orienting preliminary tests using conventional methods.

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.

Advantageously, according to the invention lithium-ion batteries with active material, such as tin, lead and in particular

Silicon, accessible, which have high volumetric capacity and also show a stable electrochemical behavior even after loading and unloading cycles and thus have a high reversible capacity. 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 following examples serve to further illustrate the invention:

Example 1 :

Production of non-aggregated, splinter-shaped, μτη-sized silicon particles by milling:

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 measurement of the particle distribution on the product obtained by static laser scattering using the Mie model with a Horiba LA 950 in a highly diluted suspension in ethanol gave dlO = 2.23 μπι, d50 = 4.48 μτη and d90 = 7.78 μηι and a width (d90-dl0) of 5.5 μιτι. The product consisted of single, non-aggregated, sliver-shaped particles (SEM).

Example 2:

Anode with the silicon particles from Example 1:

29.709 g at 85 ° C to constant weight dried polyacrylic acid (Sigma-Aldrich, Mw -450,000 g / mol) and 751.60 g of deionized water were shakers (290 1 / min) for 2.5 h until complete solution the polyacrylic acid moves. Lithium hydroxide monohydrate (Sigma-Aldrich) was added portionwise to the solution until the pH was 7.0 (measured with pH meter WTW pH 340i and probe SenTix RJD). The solution was then mixed by means of a shaker for a further 4 h. 7.00 g of the silicon particles from example 1 were then dissolved in 12.50 g of the neutralized polyacrylic acid solution (concentration 4% by weight) and 5.10 g of deionized water by means of a dissolver at a circulation speed of 4.5 m / s for 5 min and from 12 m / s for 30 min with cooling at 20 ° C dispersed. After addition of 2.50 g of graphite (Imerys, KS6L C) was then stirred for a further 30 min at a peripheral speed of 12 m / s. After degassing, 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 μιτι. Samples (diameter = 15 mm) of the resulting anode were then compacted in a die (Specac, diameter = 20 mm) by means of a manual hydraulic press (Specac, 15 t) to obtain anodes with thicknesses of anode coatings, as shown in Table 1 indicated. Table 1: Anode coatings of (comparative) Examples 2a, 2b and 2c:

a) Thickness of the porous anode coating determined by means of the measuring device "digital dial gauge Mitutoyo" (1 μτη to 12.7 mm)

Feinmess table ·

b) density p _B : density of the porous anode coating; determined as indicated above in the general description; c) porosity φ determined by means of Hg porosimetry (Porotec,

Pascal 140/440) according to DIN 66133.

The formula I according to the invention gives for the anodes 2a to 2c, taking into account the respective degree of lithiation mentioned in Table 2, the following ranges for the porosity:

- Anode according to Example 2a:

Porosity φ: range of 31.2 to 45.1%;

- Anode according to Example 2b:

Porosity φ: range of 21.3 to 30.8%;

Anode according to Example 2c:

Porosity φ: range of 43.6 to 62.9%.

The porosities listed in Table 1, measured by Hg porosimetry, are only for the anode 2a in the porosity range according to formula I.

The anode 2a is thus according to the invention, while the anodes 2b and 2c are not.

Example 3:

Lithium-ion battery with the anode of Example 2a:

The electrochemical investigations were carried out on a coin cell (type CR2032, Hohsen Corp.) in 2-electrode arrangement. The electrode coating of Example 2a was used as a counter-electrode or negative electrode Ge ^¬ (diameter = 15 mm), a coating based on lithium-nickel-manganese Cobalt oxide 1: 1: 1 with a content of 94.0% and average basis weight of 14.5 mg / cm ² (supplied by the company Custom Cells) used as a working electrode or positive electrode (diameter = 15 mm). A 120 μΐ electrolyte soaked glass fiber filter paper (hatman, GD Type D) served as a separator (diameter = 16 mm). 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). 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.

Due to the formulation in Examples 2 and 3, 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 β is 2.46 mAh / cm ² , the degree of lithiation α is 28.8%, the volumetric anodization the capacity is 1116 mAh / cra ³ . The area-related delithiation capacity β, the degree of lithiation α and the volumetric anode capacity were determined according to the methods given above in the general description.

In the second cycle (C / 2) it has a reversible capacity of 2.03 mAh / cm ² and after 203 charge / discharge cycles it still has 80% of its capacity from the second cycle.

Thus, the full cell of Example 3 had a high volumetric capacity and showed little fading.

Comparative Example 4 (VBsp.4):

Lithium-ion battery with the anode of 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 ^¬ lenzahl.

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 β is 2.43 mAh / cm ² , the degree of lithiation α is 28.5%, and the volumetric anode capacity is 759 mAh / cm ³ .

In the second cycle (C / 2) it has a reversible capacity of 2.01 mAh / cm ² and after 194 charge / discharge cycles it still has 80% of its capacity from the second cycle.

The full cell of Comparative Example 4 had a much lower volumetric capacity and moreover a more pronounced fading than the full cell of Example 3.

Comparative Example 5 (VBs .5):

Lithium-ion battery with the anode of 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 β is 2.50 mAh / cm ² , the degree of lithiation a 29.3%, the volumetric anode capacity 1561 mAh / cm ³ .

In the second cycle (C / 2) it has a reversible capacity of 2.02 mAh / cm ² and after 50 charge / discharge cycles it still has 80% of its capacity from the second cycle.

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.

Table 2 s Examination results with the lithium ion batteries of (comparative) Examples 3, 4 and 5

* in the first cycle (C / 25)

Claims

claims

1. anodes of lithium-ion batteries,

the anodes comprise porous anode coatings with volumetric capacities of 800 800 mAh / cm ³ and current collectors, and

the porous anode coatings are based 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, the particles containing active material being at least 90% by weight. %, based on the total weight of the particles containing active material, of an element selected from the group consisting of silicon, tin and lead, characterized in that

with an active material content of 5 to 30 wt .-%, bezo ^¬ gene on the total weight of the porous anode coating, a porosity φ from the range 6-61 vol .-% have; or

have with an active material content of 30 to 60 wt .-%, bezo ^¬ gene on the total weight of the porous anode coating, a porosity φ from the range from 19 to 71 vol .-%; or

c) porous anode coatings having a degree of lithiation α in the range of 0.20 to 0.50 and

have with an active material content of 60 to 85 wt .-%, bezo ^¬ gene on the total weight of the porous anode coating, a porosity φ from the range from 23 to 72 vol .-%; or

d) porous anode coatings with a degree of lithiation of 0.95 to 1.00 and

with an active material content of 5 to 30% by weight, based on the total weight of the porous anode coating, have a porosity φ in the range of 11 to 61 vol .-%.

Anodes of lithium-ion batteries according to claim 1, characterized in that

the porous anode coatings a) having silicon as the active material have a density (p _B ) of 0.92 to 2.31 g / cm ³ ; and the porous anode coatings b) having silicon as active material have a density (p _B ) of 0.77 to 1.96 g / cm ³ ; and the porous anode coatings c) having silicon as the active material have a density (p _B ) of 0.77 to 1.84 g / cm ³ ; and the porous anode coatings d) having silicon as the active material have a density (p _B ) of 0.92 to 2.18 g / cm ³ .

Anodes of lithium-ion batteries,

the anodes comprising porous anode coatings with volumetric capacities of> 800 mAh / cm ³ and current collectors, and

the porous anode coatings based on at least an active material in the form of particles, one or more Bin demitteln ^¬ optionally graphite, optionally one or more further electrically conductive components, and optionally one or more additives, wherein the active material-containing particles composed of at least 90th %, based on the total weight of the particles containing active material, of an element selected from the group consisting of silicon, tin and lead, characterized in that

the porous anode coatings have a porosity φ in the range of 0.9 * φ ^ <φ <1.3 * φ <^, in which φ _0ρί according to the following formula I

φο _ρί = 9 _AM * * K (I) determines where

Φ _Α Μ for the percentage volume fraction of the unlithiated

Active material on the total volume of the unlithiated Porö ^¬ sen anode coating is

represents the degree of lithiation of the active material in the porous anode coating and can assume values of 0 <<1, and κ for silicon the value of 3.00, for tin the value of 2.44 and for lead the value of 2.22 and.

Anodes of lithium-ion batteries according to claim 3, characterized in that the porosity φ of porous anode coatings is greater than 0 vol% and less than 75 vol%.

Anodes of lithium-ion batteries according to claim 1 to 4, characterized in that the active material is silicon in the form of particles with volume-weighted particle size distribution between the diameter percentiles d _x0 ^ 0.2 μιη and d ₉₀ ^ 20.0 μιη present.

Anodes of lithium-ion batteries according to claim 1 to 5, characterized in that the active material is silicon in the form of particles having a volume-weighted particle size distribution d ₅₀ of 0.5 to 10.0 pm.

Anodes of lithium-ion batteries according to claim 1 to 6, characterized in that the porous anode coatings in the fully charged lithium-ion batteries are only partially lithiated.

Anodes of lithium-ion batteries according to claim 7, characterized in that in the partially lithiated porous anode coatings of the fully charged lithium-ion batteries, the ratio of the lithium atoms to the active material atoms is 0,2 0.22 and 2,2 2.2 ,

9. anodes of lithium-ion batteries according to claim 7 or 8, characterized in that

the capacity of the active material of the porous anode coatings of the lithium-ion batteries is used to ^ 50% based on the maximum capacity per gram of active material, the maximum capacity for silicon being 4200 mAh / g, for tin 993 mAh / g and for lead 582 mAh / g.

10. Lithium-ion batteries containing anodes with porous anode coatings according to claim 1 to 9.