Triweekly Patent Update

A solid-state battery with enhanced cycling stability was developed by incorporating a porous graphene functional layer between the negative electrode and solid electrolyte (Li₆PS₅Cl, see Figure). The battery comprises a positive electrode layer, negative electrode layer, functional layer on at least one surface of the negative electrode, and solid electrolyte layer between the functional layer and positive electrode.

The functional layer includes porous graphene-like materials with individual sheet porosity of 3-9% and average pore diameter of 0.2-15 nm. At ≤10% state of charge (SOC), the porous graphene-like material comprises 91-100 mass% of the functional layer.

Porous reduced graphene oxide was synthesized by oxidizing graphene powder (average flake diameter: 50 μm, average thickness: 2 nm) in mixed oxidizing solution containing hydrogen peroxide solution (20%) and ammonia solution (25%) at 40°C for 1.5 h, followed by reduction with hydrazine hydrate at 90°C for 2 h. The resulting material (5% individual sheet porosity, 2 nm average pore diameter, 50 μm average flake diameter) was spin-coated onto copper foil to form a 300 nm functional layer.

Full cells with NCM811 positive electrodes and lithium metal negative electrodes exhibit 82% capacity retention after 200 cycles (0.5 C charge/discharge, 25°C, 2-4.35 V).

1211: positive electrode current collector
1212: positive electrode active layer
122: solid electrolyte layer
124: functional layer
1231: negative electrode current collector
1232: negative electrode active layer

A solid electrolyte membrane for all-solid-state batteries was developed using an asymmetric lithium salt to enhance mechanical flexibility and ionic conductivity. The membrane comprises Li₆PS₅Cl (LPSCl, D₅₀: 3 μm), binder blend (polyvinylidene fluoride/hexafluoropropylene copolymer and acrylic polymer, mass ratio 1 : 1), and asymmetric lithium salt (FSO₂)LiN(SO₂CF₃) with mass ratio 96.21 : 3.00 : 0.15 (see Figure).

The asymmetric lithium salt features different fluorinated groups (R₁ = -F, R₂ = -CF₃), lowering the melting point to 100°C compared to symmetric LiTFSI (235°C). An 8 mass% binder solution in octyl acetate was prepared, followed by LPSCl and lithium salt addition, then mixed. The slurry was applied onto a nonwoven fabric using a bar coater. First drying was performed in a convection oven (110°C, 15 min), followed by second drying in a vacuum oven (90°C, 4 h). During second drying, the lithium salt melts and diffuses between sulfide electrolyte particles with the binder.

The resulting membrane exhibits an ionic conductivity of 8.3 × 10^-4 S/cm at 25°C, compared to 6.4 × 10^-4 S/cm without lithium salt, 6.5 × 10^-4 S/cm with symmetric LiTFSI, and 7.4 × 10^-4 S/cm with Li(SO₂C₄F₉)₂. Binder content is 2-25 mass% (10-15 mass% preferred), with binder to lithium salt mass ratio of 20 : 1. No electrochemical cycling data was identified.

PAM: positive electrode active material (NCM, NCA, or LFP)
SE2: second solid electrolyte (Li₆PS₅Cl or Li₆PS₅Br)
BND2: second binder (polyvinylidene fluoride or styrene butadiene rubber)
LTS2: second lithium salt ((FSO₂)LiN(SO₂CF₃))
SE1: first solid electrolyte (Li₆PS₅Cl)
BND1: first binder (PVdF-HFP and acrylic polymer)
LTS1: first lithium salt ((FSO₂)LiN(SO₂CF₃))
120: positive electrode active material layer
300: solid electrolyte layer

A solid-state electrolyte (SSE) was developed comprising a dense Li₇La₃Zr₂O₁₂ (LLZO) membrane with a thickness of 15-45 µm. The membrane exhibits a density ≥90% of theoretical density. Preferably, the LLZO is aluminum-doped (Al-LLZO).

The membrane was heated (800-900°C) in argon atmosphere to remove surface contaminants, particularly Li₂CO₃. An antimony (Sb) coating with a thickness of 5-10 nm was deposited on the cleaned surface using RF magnetron sputtering. During deposition, a first Li-Sb alloy formed at the interface between the Sb coating and LLZO membrane through solid-state diffusion of lithium from the LLZO into the Sb layer.

For battery assembly, a lithium metal negative electrode was placed adjacent to the Sb-coated surface. The assembly was compressed isostatically (71 MPa for 45 µm membranes) and heated (200-300°C) in argon atmosphere. This formed a second Li-Sb alloy at the lithium metal/Sb interface.

The SSE exhibits an interface resistance of 5.35 Ω·cm² at room temperature and 0.129 Ω·cm² at 75°C. The critical current density reaches 3.62 mA/cm² at room temperature and 70 mA/cm² at 75°C for the 45 µm membrane. Symmetric lithium cells demonstrated stable cycling for 1,730 cycles (≈1,800 h) at 75°C and 4 mA/cm².

Porous carbon (BET surface area: 1,940 m²/g, pore volume: 1 cm³/g) was heated to 150°C under nitrogen flow. The material contains OH groups and C_xH_y groups at active sites, with CO gas detected at ≈8,000 ppm in the exhaust.

Monosilane gas was introduced at 365-380°C under pressurized atmosphere (50 kPa). CO gas from active sites enables low-temperature monosilane decomposition, depositing silicon oxide with dangling bonds. Oxygen atoms from active sites bond with silicon, forming Si-O structures internally.

After cooling, oxidation was performed under 20 kPa pressurized atmosphere using nitrogen-diluted oxygen (1 mass% O₂), creating low-valence nano-silicon oxide with a defect-rich SiO_x structure at the surface. The material was then heat-treated to partially crystallize the Si.

The material was heated to 600°C to form Si-C bonds in the bulk interior. Carbon layer deposition was performed at 580°C using acetylene gas under reduced pressure (10 kPa, 8 h). At the interface, oxygen transfer creates C=O or C-O bonds.

The material exhibits an Si grain size of 4.6 nm. In half-cells, the material exhibits a discharge capacity of 1,860 mAh/g, initial efficiency of 89%, and 1,000-cycle retention of 81%. ²⁹Si MAS-NMR analysis confirms the presence of both Si-C bonds and amorphous Si / low-valence silicon oxide (see Figure).

Si-C: Si-C bonds
非晶質Si: Amorphous Si

A multi-staged metallothermic reduction process was developed to produce silicon nanoparticles with reduced thermal moderator requirements.

A first mixture containing silica (SiO₂) precursor, thermal moderator (e.g., NaCl, MgCl₂), and a first fraction of magnesium (Mg) metal reducing agent was provided to a rotary tube furnace. The mixture was pre-treated under continuous rotation in an inert atmosphere (argon or nitrogen).

A first thermal treatment was performed by heating to 490-530°C to initiate the reduction reaction:
SiO₂ + 2Mg → Si + 2MgO

After cooling, a second fraction of Mg was added to the treated first mixture to form a second mixture. A second thermal treatment was performed at 530-760°C to complete the conversion to silicon nanoparticles.

For a two-step process, the first Mg fraction ranges from 10-60 mass% and the second fraction from 40-90 mass%. The mass ratio of SiO₂ to total Mg is 1 : 1 to 1 : 1.1. The thermal moderator : reactants ratio is ≤1 : 1, compared to 4 : 1 in one-step processes. The approach increases silicon nanoparticle production throughput by up to 50%, reduces water consumption for post-processing, and improves recovery of valuable MgCl₂ byproduct.

100: rotary tube furnace
101: pedestal
102: material inlet
104: reactant feed hopper
105: feeding speed control
106: rotating tube
106A: first opening (inlet side)
106B: second opening (outlet side)
108: material outlet
110: product hopper
112: magnetic fluid sealing element (inlet)
114: magnetic fluid sealing element (outlet)
116: chiller (for sealing elements)
122: gas inlet
124: pressure gauge
130: mixing module
132: screw feeder
134: motor and bearings
138: rotation speed control
140: mass flow readout device
142: chiller (for motor)
146: temperature gauge
148: slide sealing element
150: heating module
152: heating elements
153: controller
154: insulating chamber
155: chamber door
156: locks
162: tilting element
164: tilting control
170: vacuum module
172: vacuum pump
174: vacuum gauge
180: control panel
190: emergency stop
HZ1, HZ2, HZ3: heating zones with independent temperature control

A silicon-carbon composite material was prepared comprising a carbon phase with a silicon phase dispersed within the carbon phase. The patent describes synthesis pathways including direct mixing and sintering of metallurgical silicon with carbon sources, or monosilane gas deposition on porous carbon followed by magnesium vapor reduction, but does not specify which method was used for the tested examples. The composite exhibits a single particle fracture strength of 340 MPa (average particle diameter D₅₀: 7.1 μm, specific surface area: 3.7 m²/g). X-ray diffraction analysis exhibits a peak at 2θ ≈ 28.0° attributed to the Si (111) plane with a full width at half maximum of 6.4°, corresponding to Si crystallite sizes of approximately 1.3 nm (calculated using the Scherrer equation with K = 0.9 and Cu Kα radiation).

A negative electrode slurry was prepared by mixing graphite and silicon-carbon composite (90 : 10 mass ratio, total 98 mass%), carbon nanotube (CNT) conductive agent, styrene-butadiene rubber (SBR) binder (1 mass%), and carboxymethyl cellulose (CMC) thickener (1 mass%) in water. The CNT exhibits a length of 5.2 μm, a diameter of 1.6 nm, and a Raman G/D ratio of 94. The CNT content was 0.015 parts by mass per 100 parts of negative electrode active material.

A positive electrode was prepared with Li_1.05Ni_0.80Co_0.15Al_0.05O₂ (98 mass%), carbon black (1.4 mass%), and polyvinylidene fluoride (PVDF, 0.6 mass%).

Full cells were assembled with a polyethylene separator and an electrolyte consisting of ethylene carbonate (EC) / dimethyl carbonate (DMC) (1 : 3 by volume) with 5 mass% vinylene carbonate (VC) and 1.5 mol/L LiPF₆.

After 1,000 cycles (0.2 C charge / discharge, 4.1 V charge cutoff, 3.0 V discharge cutoff, 25°C), cells exhibit a cycle retention of 98%, as compared to 84% for comparative cells using the same silicon-carbon composite but with shorter CNT fibers (1.8 μm length instead of 5.2 μm).

A hydroxide precursor Ni_0.96Co_0.01Mn_0.03(OH)₂ was synthesized via co-precipitation (50-60°C, pH 10-12, 1,000 rpm). The precursor was mixed with LiOH (Li to transition metal molar ratio of 1.01), Al(OH)₃ (0.1 mol), ZrO₂ (0.1 mol), and deionized water (3-6 mass%), followed by compression molding (see Figure).

The molded bodies were sintered in a roller hearth kiln without using sintering vessels (oxygen atmosphere, ramp to 700-900°C, hold 8-10 h) to obtain Ni_0.966Co_0.01Mn_0.03O₂ doped with Zr and Al. The sintered bodies were crushed using a jet mill (1.2-2 bar) to obtain cathode active material powder comprising single particles.

The material exhibits an XRD (003) plane grain size of 237 nm compared to 85-91 nm for comparative material.

In half-cells, the material exhibits a discharge capacity of 214.5 mAh/g (0.2 C, 25°C, 2.5-4.25 V vs. Li⁺/Li), a first cycle efficiency of 86.4%, and a capacity retention after 50 cycles of 86.8% (0.5 C / 1 C charge / discharge).

100: molded sintered body (green body)
30: drive roller

Elemental nickel, manganese and cobalt metals were used as precursors in a sequential digestion process. Equal molar amounts of manganese and cobalt were first dispersed in oxalic acid (1.00-1.05 molar excess) and stirred at room temperature (≈20 h) to form metal oxalates without peroxide addition. Nickel metal was then added (4 moles Ni per combined mole of Mn and Co), followed by simultaneous addition of oxalic acid (1.00-1.03 molar excess) and hydrogen peroxide (1.33:1 molar ratio) over ≈1 h, maintaining temperature below 60°C. Lithium carbonate was added after nickel digestion completion (≈1.2 moles Li per mole of peroxide). The mixture was stirred (≈4 h), dried, and calcined to produce LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) with rock-salt crystal structure.

The inventors claim that sequential digestion (Mn/Co first without peroxide, then Ni with peroxide) improves transition metal homogeneity in the precursor compared to methods where all metals are added simultaneously, though specific TEM-EDX data is not provided in the patent. The oxalate precursor decomposes at ≈300°C without additional oxygen, enabling better calcination temperature control compared to acetate-based methods. No electrochemical performance data is provided in this patent application.

LiMn_0.7-0.8Fe_0.3-0.2PO₄ was synthesized via a two-step precursor method using ferromanganese as the metal source. Ferromanganese (Fe : Mn molar ratio ≈20-30 : 70-80) was added to water, followed by dropwise addition of 85 mass% phosphoric acid. The mixture was stirred (200 rpm, 1 h) until hydrogen evolution ceased. The resulting slurry was pulverized (planetary mill, 5 mm beads, 15 min) and filtered (75 μm opening) to obtain first precursor particles.

The first precursor particles were mixed with lithium carbonate (added over 30 min) and stirred (200 rpm). Fructose was added as a carbon source, followed by stirring (30 min). The slurry was pulverized (bead mill, 0.1 mm beads, 90 min), filtered (75 μm opening), and spray-dried.

The resulting particles were calcined (5°C/min to 680°C, 3 h, argon atmosphere) to obtain the final LiMn_0.7-0.8Fe_0.3-0.2PO₄ material (see Figure). Electrochemical performance data was not identified in the patent.

A cellulose nanofibril (CNF) adhesive material was developed as a PFAS-free interface layer for polymer electrolyte membrane fuel cell (PEMFC) membrane electrode assemblies (MEAs).

The adhesive material comprises a colloidal dispersion of cellulose nanofibrils at a concentration of 2-10 g/l. The cellulose nanomaterial can be chemically modified to exhibit aldehyde groups (0.5-1 mmol/g dry nanomaterial), sulfonate groups (200-1500 μmol/g), or other functional groups such as carboxymethyl, phosphor, or sulfoethyl groups on the nanofiber surfaces.

Two commercial platinum gas diffusion electrodes were prepared. The cellulose dispersion was placed on one side of a cellulose-based proton exchange membrane and a Pt-GDE was added. The assembly was hot-pressed (70°C, 60 s). The cellulose dispersion was applied to the opposite membrane side, the second Pt-GDE was aligned, and hot-pressing was repeated (70°C, 60 s).

Fuel cell testing was performed with H₂ and air at 40°C and 80% relative humidity. The Pt-GDEs were activated at 300 mV. Polarization curves for MEAs assembled with the sulfoethylated cellulose nanofibril adhesive exhibit similar performance compared to conventional Nafion ionomer-based MEAs (see Figure).

membrane_SE: sulfoethylated cellulose ionomer MEA
membrane_SE_Nafion: Nafion ionomer MEA