# US 10,374,214 B2 · Method for the production of electrodes and electrodes made using such a method

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- Number: US 10,374,214 B2
- Document ID: US10374214B2
- Status: Granted
- Kind: B2
- Application number: 14/785,163
- Filed: 2014-04-16
- Published: 2016-03-31
- Granted: 2019-08-06
- Earliest claimed: 2013-04-16
- Assignees: ETH Zurich
- Applicants: Eth Zurich
- Inventors: Vanessa Wood; Martin Otto Johann Ebner
- Web page: https://patentgrep.com/patent/US10374214B2

## CPC

- H01M 4/04: Processes of manufacture in general
- C25B 11/031: Porous electrodes
- H01G 9/0029: {Processes of manufacture}
- H01G 9/042: characterised by the material (H01G11/22 takes precedence)
- H01G 9/055: Etched foil electrodes
- H01G 9/15: Solid electrolytic capacitors (H01G11/00 takes precedence)
- H01M 4/0404: {by coating on electrode collectors}
- H01M 4/0409: {by a doctor blade method, slip-casting or roller coating}
- H01M 4/13: Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M 4/139: Processes of manufacture
- H01M 4/8605: {Porous electrodes}
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 2004/021: {Physical characteristics, e.g. porosity, surface area}
- H01M 2220/20: Batteries in motive systems, e.g. vehicle, ship, plane
- H01M 2220/30: Batteries in portable systems, e.g. mobile phone, laptop
- Y02E 60/10: Energy storage using batteries
- Y02E 60/50: Fuel cells
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- C25B: ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR (anodic or cathodic protection C23F13/00; single-crystal growth C30B)
- H01G: CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE (selection of specified materials as dielectric H01B3/00; capacitors having potential barriers H10D1/62, H10K10/10)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A method for the manufacturing of electrodes with at least one porous surfacial layer comprising anisotropic electrochemically active particles. It also relates to electrodes made using such a method. The method comprises the following steps: (a) coupling of paramagnetic nanoparticles to said active particles for the generation of composites; (b) preparation of a slurry of said composites, including a solvent mixed with a binder able to release a volatile component; (c) application of said slurry to a substrate to form a film; (d) application of a magnetic field to the film and orienting said active particles leading to a substrate in which said active particles are arranged with their shortest axes aligned along a preferred axis parallel to said substrate; (e) during or after application of said magnetic field evaporation of said solvent with solidification of the binder and release of said volatile component under formation of said surfacial layer.

## Claims

### Claim 1

A method for the manufacturing of electrodes with at least one porous surfacial layer comprising anisotropically shaped electrochemically active particles having a longest axis which is at least 1.5 times longer than a shortest axis, and having a ratio of said longest axis to a second longest axis which is smaller than 2, comprising at least the following steps:
(a) coupling of paramagnetic nanometer-sized particles to the surface of said anisotropically shaped electrochemically active particles for the generation of composites of said paramagnetic nanometer-sized particles with said anisotropically shaped electrochemically active particles;
(b) preparation of a slurry of said composites of said paramagnetic nanometer-sized particles with said anisotropically shaped electrochemically active particles, said slurry including a solvent mixed with a binder or a liquid binder able to release a volatile or elutable component;
(c) application of said slurry to a planar substrate to form a film having a thickness in the range of 1-1000 micro-meter;
(d) application of a magnetic field at least to the film and orienting said composites of said paramagnetic nanometer-sized particles with said anisotropically shaped electrochemically active particles leading to a slurry-coated substrate in which said composites of said paramagnetic nanometer-sized particles with said anisotropically shaped electrochemically active particles are arranged in that their shortest axes are, at least region-wise, essentially aligned along a common preferred axis oriented parallel to said substrate in said region; and
(e) either during or after application of said magnetic field according to step (d), conducting at least one of:
(i) evaporation of said solvent with solidification of the binder,
(ii) solidification of the binder and release of said volatile component, and
(iii) solidification of the binder and subsequent elution of the elutable component,
under a condition that said surfacial layer is formed with a solid volume fraction below 100%.

### Claim 2 (depends on 1)

The method according to claim 1, wherein in step (c) a layer with a thickness of 5-500 micro-meter is applied.

### Claim 3 (depends on 1)

The method according to claim 1, wherein in step (d) a rotating magnetic field is applied across the slurry-coated electrode, wherein the magnetic field vector rotates in a plane perpendicular to the substrate plane.

### Claim 4 (depends on 1)

The method according to claim 1, wherein a magnetic field with a flux density in the range of 1-2000 mT is applied in step (d).

### Claim 5 (depends on 1)

The method according to claim 1, wherein in step (a) the paramagnetic nanometer-sized particles are attached to the surface of the anisotropically shaped electrochemically active particles by using electrostatic adhesion in a solvent or by in-situ generation of the paramagnetic nanometer-sized particles and attachment to the anisotropically shaped electrochemically active particles in the gas phase.

### Claim 6 (depends on 1)

The method according to claim 1,
wherein the anisotropically shaped electrochemically active particles have a ratio of the longest axis to the shortest axis which is >2, or
wherein the anisotropically shaped electrochemically active particles have a ratio of the longest axis to the second longest axis which is <1.4, or
wherein the largest axis of the anisotropically shaped electrochemically active particles on average is in the range of 1-100 micro-meters, or
wherein the shortest axis of the anisotropically shaped electrochemically active particles on average is in the range of 0.1-50 micro-meters, or
wherein the anisotropically shaped electrochemically active particles are selected from the group consisting of: intercalation compounds such as graphite, transition metal oxides, phosphates, conversion (displacement) reaction materials, Lithium alloys, or combinations thereof.

### Claim 7 (depends on 1)

The method according to claim 1,
wherein said slurry further comprises additives, including processing aids, conductivity agents, dispersion agents, and combinations thereof, or
wherein the binder used is a polymeric binder, including the ones selected from the group consisting of: styrene butadiene rubber; nitrile butadiene rubber; methyl (meth) acrylate butadiene rubber; chloroprene rubber; carboxy modified styrene butadiene rubber; modified polyorganosiloxane polymer; polyvinylidene Fluoride (PVDF) as well as derivatives and combinations thereof and wherein the solvent is at least one of an organic solvent or water, wherein the organic solvent includes those selected from the group consisting of: N methyl pyrrolidone (NMP), ethanol, acetone, water or derivatives or mixtures thereof.

### Claim 8 (depends on 1)

The method according to claim 1, wherein said planar substrate is electrically conducting.

### Claim 9 (depends on 1)

The method according to claim 1, wherein application of the slurry to the planar substrate in step (c) takes place by means of pasting, doctor-blading, web-coating, rolling, screen printing, solution casting, or spray deposition or a combination thereof.

### Claim 10 (depends on 1)

The method according to claim 1, wherein subsequent to step (e) the film is subjected to a heat annealing treatment, or wherein subsequent to step (e) the paramagnetic particles are removed from the layer.

### Claim 11 (depends on 1)

The method according to claim 1, wherein the paramagnetic nanometer-sized particles are selected to be superparamagnetic nanometer-sized particles.

### Claim 12 (depends on 1)

An electrode with at least one porous surfacial layer obtained or obtainable by using a method according to claim 1 or electric or electronic device, an energy storage or delivery device, an analytical device, a chemical synthesis device, or combinations thereof, comprising at least one such electrode.

### Claim 13 (depends on 1)

The method according to claim 1, wherein in step (c) a layer with a thickness of 10-50 micro-meter is applied.

### Claim 14 (depends on 1)

The method according to claim 1,
wherein in step (d) a homogeneous, rotating magnetic field is applied across the slurry-coated electrode,
wherein the magnetic field vector rotates in a plane perpendicular to a substrate plane of said planar substrate,
wherein the magnetic flux density (B) of the rotating magnetic field is adjusted such that the minimum of the total energy (UM+UG) given by the sum of the magnetic (UM) and gravitational (UG) energies occurs at out-of-plane aligned particles for an inclination angle thereof of Θ=π/2, and
wherein the required magnetic flux is calculated based on the following formulae for the value of a particle-based variable C1 and the magnetic (UM) and gravitational (UG) energies:
U
G
=
V
p
·
(
ρ
p
-
ρ
f
)
·
g
·
b
·
Sin
⁡
(
Θ
)
U
M
=
C
1
·
(
B
μ
0
)
2
·
Sin
2
⁡
(
π
2
-
Θ
)
C
1
=
2
⁢
π
3
·
[
(
a
+
Δ
)
·
(
b
+
Δ
)
2
-
a
·
b
2
]
·
μ
0
·
χ
p
2
χ
p
+
1
wherein B is the magnetic flux density of the rotating magnetic field, Θ is the inclination angle of the particles, Vp is the particle volume, ρp and ρf, are the particle and fluid densities, respectively, g is the gravitational acceleration, a is one-half the particle thickness, b is one-half the particle diameter, Δ is the paramagnetic nanometer-sized particle coating thickness, μ0 is the permeability of vacuum, and χp is an effective coating magnetic susceptibility.

### Claim 15 (depends on 1)

The method according to claim 1, wherein in step (d) a homogeneous, rotating magnetic field is applied across the slurry-coated electrode, wherein the magnetic field vector rotates in a plane perpendicular to the substrate plane, wherein the magnetic flux density (B) of the rotating magnetic field is adjusted such that the minimum of the total energy (UM+UG) given by the sum of the magnetic (UM) and gravitational (UG) energies occurs at out-of-plane aligned particles for an inclination angle thereof of Θ=π/2, wherein for disc-shaped particles the required magnetic flux is calculated based on the following formulae for the value of a particle-based variable C1 and the magnetic (UM) and gravitational (UG) energies:
U
G
=
V
p
·
(
ρ
p
-
ρ
f
)
·
g
·
b
·
Sin
⁡
(
Θ
)
U
M
=
C
1
·
(
B
μ
0
)
2
·
Sin
2
⁡
(
π
2
-
Θ
)
C
1
=
2
⁢
π
3
·
[
(
a
+
Δ
)
·
(
b
+
Δ
)
2
-
a
·
b
2
]
·
μ
0
·
χ
p
2
χ
p
+
1
wherein B is the magnetic flux density of the rotating magnetic field, Θ is the inclination angle of the particles, Vp is the particle volume, ρ2 and ρf, are the particle and fluid densities, respectively, g is the gravitational acceleration, a is one-half the particle thickness, b is one-half the particle diameter, Δ is the paramagnetic nanometer-sized particle coating thickness, μ0 is the permeability of vacuum, and χp is an effective coating magnetic susceptibility.

### Claim 16 (depends on 1)

The method according to claim 1, wherein a magnetic field with a flux density in the range of 100-500 mT is applied, and in case of a rotating magnetic field the rotation frequency is in the range of 1-10 Hz.

### Claim 17 (depends on 1)

The method according to claim 1,
wherein the anisotropically shaped electrochemically active particles have a ratio of the longest axis to the shortest axis which is larger than 5
wherein the anisotropically shaped electrochemically active particles have a ratio of the longest axis to the second longest axis which is smaller than 1.25, or
wherein the largest axis of the anisotropically shaped electrochemically active particles on average is in the range of 1-40 micro-meters, or
wherein the shortest axis of the anisotropically shaped electrochemically active particles on average is in the range of 1-10 micro-meters.

### Claim 18 (depends on 1)

The method according to claim 1, wherein said slurry further comprises additives, including processing aids, conductivity agents, dispersion agents, and combinations thereof or wherein the binder used is a polymeric binder, selected from the group consisting of: styrene butadiene rubber; nitrile butadiene rubber; methyl(meth)acrylate butadiene rubber; chloroprene rubber; carboxy modified styrene butadiene rubber; modified polyorganosiloxane polymer; polyvinylidene Fluoride (PVDF) as well as derivatives and combinations thereof and wherein the solvent is at least one of an organic solvent or water, wherein the organic solvent is selected from the group consisting of: N methyl pyrrolidone (NMP), ethanol, acetone, water or derivatives or mixtures thereof.

### Claim 19 (depends on 1)

The method according to claim 1, wherein said planar substrate is electrically conducting, in the form of a foil, grid, woven or non-woven based on carbon, electrically conductive polymer, copper, aluminum, titanium, nickel, silver, gold, stainless steel, or alloys thereof.

### Claim 20 (depends on 1)

The method according to claim 1, wherein paramagnetic nanometer-sized particles are selected from the group of coated or uncoated, surfactant stabilised or surfactant unstabilised, electrostatically stabilised or electrostatically unstabilised particles based on: iron oxide, such as Fe3O4, Fe2O3, cobalt, nickel, and derived alloy based particles.

### Claim 21 (depends on 1)

The method according to claim 1, wherein the paramagnetic nanometer-sized particles have a size range of 1-50 nm in diameter.

### Claim 22 (depends on 1)

An electrode with at least one porous surfacial layer obtained or obtainable by using a method according to claim 1.

### Claim 23 (depends on 1)

A device comprising at least one electrode with at least one porous surfacial layer obtained or obtainable by using a method according to claim 1.

### Claim 24 (depends on 1)

A battery comprising at least one electrode made using a method according to claim 1,
wherein the porous surfacial layer comprises anisotropically shaped electrochemically active particles having a longest axis which is at least 1.5 times longer than the shortest axis, and having a ratio of the longest axis to a second longest axis which is smaller than 1.5,
wherein the anisotropically shaped electrochemically active particles are embedded and held together by a binder and are arranged in said layer in that their shortest axes are, at least region-wise, essentially aligned along a common preferred axis oriented parallel to said planar substrate in said region, and
wherein said surfacial layer has a thickness in the range of 20-50 micro-meter and has a solid volume fraction in the range of 50-80%.

### Claim 25 (depends on 2)

The method according to claim 2, wherein in step (d) a rotating magnetic field is applied across the slurry-coated electrode, wherein the magnetic field vector rotates in a plane perpendicular to the planar substrate plane.

### Claim 26 (depends on 2)

The method according to claim 2,
wherein in step (d) a homogeneous, rotating magnetic field is applied across the slurry-coated electrode,
wherein the magnetic field vector rotates in a plane perpendicular to a substrate plane of said planar substrate,
wherein the magnetic flux density (B) of the rotating magnetic field is adjusted such that the minimum of the total energy (UM+UG) given by the sum of the magnetic (UM) and gravitational (UG) energies occurs at out-of-plane aligned particles for an inclination angle thereof of Θ=π/2, and
wherein the required magnetic flux is calculated based on the following formulae for the value of a particle-based variable C1 and the magnetic (UM) and gravitational (UG) energies:
U
G
=
V
p
·
(
ρ
p
-
ρ
f
)
·
g
·
b
·
Sin
⁡
(
Θ
)
U
M
=
C
1
·
(
B
μ
0
)
2
·
Sin
2
⁡
(
π
2
-
Θ
)
C
1
=
2
⁢
π
3
·
[
(
a
+
Δ
)
·
(
b
+
Δ
)
2
-
a
·
b
2
]
·
μ
0
·
χ
p
2
χ
p
+
1
wherein B is the magnetic flux density of the rotating magnetic field, Θ is the inclination angle of the particles, Vp is the particle volume, ρn and ρf, are the particle and fluid densities, respectively, g is the gravitational acceleration, a is one-half the particle thickness, b is one-half the particle diameter, A is the paramagnetic nanometer-sized particle coating thickness, μ0 is the permeability of vacuum, and χp is an effective coating magnetic susceptibility.

### Claim 27 (depends on 2)

The method according to claim 2,
wherein in step (d) a homogeneous, rotating magnetic field is applied across the slurry-coated electrode,
wherein the magnetic field vector rotates in a plane perpendicular to a substrate plane of said planar substrate,
wherein the magnetic flux density (B) of the rotating magnetic field is adjusted such that the minimum of the total energy (UM+UG) given by the sum of the magnetic (UM) and gravitational (UG) energies occurs at out-of-plane aligned particles for an inclination angle thereof of Θ=π/2, and
wherein for disc-shaped particles the required magnetic flux is calculated based on the following formulae for the value of a particle-based variable C1 and the magnetic (UM) and gravitational (UG) energies:
U
G
=
V
p
·
(
ρ
p
-
ρ
f
)
·
g
·
b
·
Sin
⁡
(
Θ
)
U
M
=
C
1
·
(
B
μ
0
)
2
·
Sin
2
⁡
(
π
2
-
Θ
)
C
1
=
2
⁢
π
3
·
[
(
a
+
Δ
)
·
(
b
+
Δ
)
2
-
a
·
b
2
]
·
μ
0
·
χ
p
2
χ
p
+
1
wherein B is the magnetic flux density of the rotating magnetic field, Θ is the inclination angle of the particles, Vp is the particle volume, ρp and ρf, are the particle and fluid densities, respectively, g is the gravitational acceleration, a is one-half the particle thickness, b is one-half the particle diameter, A is the paramagnetic nanometer-sized particle coating thickness, μ0 is the permeability of vacuum, and χp is an effective coating magnetic susceptibility.

### Claim 28 (depends on 1)

The method according to claim 1, wherein a rotating magnetic field with a rotation frequency in the range of 0.1-1000 Hz is applied in step (d).

### Claim 29 (depends on 1)

The method according to claim 1, wherein the paramagnetic nanometer-sized particles are selected to be superparamagnetic nanometer-sized particles, selected from the group of coated or uncoated, surfactant stabilised or surfactant unstabilised, electrostatically stabilised or electrostatically unstabilised particles based on: iron oxide, such as Fe3O4, Fe2O3, cobalt, nickel, and derived alloy based particles.