Triweekly Patent Update – 2025-12-16

An anode-free all-solid-state battery was developed featuring an amorphous silicon layer on a copper current collector. The silicon layer exhibits a thickness of up to 500 nm (see Figure), resulting in Ns/P ratios (charge capacity of silicon layer to positive electrode) of less than 0.3.

The battery comprises a Li₆PS₅Cl (LPSCl) solid electrolyte separator and a positive electrode composite of NMC811 with LPSCl and vapor-grown carbon fiber (VGCF) (mass ratio : 66 : 31 : 3, 3 mAh/cm² loading). Amorphous silicon (500 nm) was deposited on Cu via sputtering. This stack was pressed at 370 MPa prior to cycling, while a stack pressure of 5 MPa was maintained during cycling.

During initial charging, silicon lithiation occurred up to 3.7 V (0.25 mAh/cm²), forming amorphous Li_xSi_1-x (0.5<x<0.79) with composition Li_0.7Si_0.3. Subsequent lithium metal plating (2.75 mAh/cm²) formed a dense lithium layer on the pre-lithiated silicon substrate. The lithiated silicon layer persists throughout cycling without further silicon participation.

Rate performance testing in the all-solid sulfide electrolyte cells exhibits stable cycling up to C/5 (0.6 mA/cm²). Thin-film cells with LiPON solid electrolyte demonstrate critical current densities up to 5.0 mA/cm², representing a five-fold improvement compared to bare Cu current collectors.

A solid-state electrochemical cell was developed featuring oriented pores with electronically conducting networks on sidewall surfaces (see Figure). The cell comprises a positive electrode, a negative electrode, and a solid-state electrolyte separator. The positive electrode active material is NMC and the negative electrode comprises lithium metal. The solid electrolyte is Li_6.95La_2.75Mg_0.15Sr_0.25Zr_2.0O₁₂.

Oriented pores were formed in both electrodes through multi-material pattern printing. A carbon precursor ink (sucrose or phenolic resin) was deposited in vertical patterns, while solid electrolyte ink was deposited surrounding the patterns. The structure was sintered to form oriented pores (pore width: 10-100 μm, sidewall length: 10-200 μm) with ionically conducting electrolyte strands extending through the electrode. During sintering, the carbon precursor decomposed to form pores while carbonizing to form electronically conducting network coatings on the pore sidewall surfaces.

The electronically conducting networks extend on pore sidewall surfaces from current collectors to the electrolyte separator. This enables entire electrode active material to function, rather than only material adjacent to current collectors. The positive electrode includes a filling aperture with a seal configured to isolate the negative electrode from cathode material.

105: ceramic electrolyte separator
150': ionically conducting solid electrolyte strands
160: oriented pores
162: pore sidewall surfaces
170: cathode active material
180: electronically conducting networks
1300: solid-state battery

A treatment process for yttrium-containing halide solid electrolytes was developed to stabilize the interface with lithium metal negative electrodes. The solid electrolyte Li₃Y(Cl,Br)₆ (LiYClBr, where the notation indicates variable Cl:Br ratios totaling 6 halogens, such as Li₃YCl₄Br₂) was contacted with lithium metal and heated (70°C, 3 cycles, C/20, 0.5 mAh/cm²).

Symmetric Li|LiYClBr|Li cells with treated electrolyte were cycled at 0.1 mA/cm^-1 and 0.5 mAh/cm² (C/5, 1,000 h). The overpotential is stable from the second cycle at 60 mV. At higher capacity (1 mAh/cm², 0.1 mA/cm^-2, C/2.5), the overpotential stabilizes at 60 mV from 100 h onward.

Post-mortem scanning electron microscopy analysis reveals that after 5 cycles, no evolution at the halide-lithium interface is observed. After 100 cycles, an yttrium-rich interlayer forms between the halide solid electrolyte and the lithium electrode. A gradient in yttrium content is noticeable within the electrolyte: less yttrium at the electrolyte surface and more in the bulk. The yttrium migrated from the halide to the lithium electrode to form a protective layer that stabilizes the interface.

Na ingots were cut into ≈5 mm pieces and mixed with Si powder in a Wonder Crusher (Si amount: 102 parts by mass per 100 parts Na). The Na ingots were added in three portions, followed by mixing for 1 min for each portion. The resulting mixture was placed in a stainless steel container, evacuated, and heated under argon flow (420°C, 40 h), which resulted in a Na-Si alloy.

AlF₃ particles were sieved with a 32 µm mesh to remove fine particles, followed by sieving with a 75 µm mesh to remove coarse particles, which resulted in an AlF₃ classified material with a D50 particle size of 56.1 µm (D10: 38.9 µm, D90: 80.2 µm).

The AlF₃ classified material was mixed with the Na-Si alloy (AlF₃ amount: 50-100 parts by mass per 100 parts Na-Si alloy). This mixture was placed in a stainless steel container, evacuated, and heated under argon flow (350°C, 60 h), resulting in silicon clathrate II.

The material exhibits a silicon clathrate II / silicon clathrate I ratio of 14.0 as measured by XRD (X-ray diffraction), as compared to 0.74 for a comparative material prepared without classification of AlF₃ particles (D50: 75.1 µm, D10: 37.6 µm, D90: 138.6 µm).

A silicon-carbon composite negative electrode material was developed based on controlled silicon loading within a highly porous carbon framework. The invention correlates silicon content mathematically to available pore volume to ensure partial pore occupancy, allowing internal accommodation of silicon expansion during lithiation.

A porous carbon framework (BET specific surface area: 1,860 m²/g, D₅₀: 3.1 μm) exhibits a P¹ pore volume of 0.88 cm³/g (P¹ represents the total volume of micropores and mesopores, i.e., pores with diameters from 0 to 50 nm, as measured by gas adsorption) with 54 mass% micropores and a PD₅₀ pore diameter of 1.4 nm (PD₉₀: 5.1 nm), confirming predominantly small mesopores and micropores suitable for silicon confinement.

Silicon was deposited via chemical vapor infiltration (CVI) in a fluidized bed reactor (83 mm diameter). The carbon framework was purged with nitrogen, heated to 400-500°C, and exposed to monosilane gas (4 vol% in nitrogen) at a flow rate sufficient to fluidize the particles. The silicon loading was controlled to achieve the target (silicon / carbon) × P¹ ratio of 1.2, corresponding to ≈35% volumetric pore occupancy.

The resulting composite exhibits 49.1 mass% silicon. Full coin cells were assembled with the silicon-carbon composite negative electrodes, NMC532-based positive electrodes (capacity ratio: ≈0.9), and 1 M LiPF₆ in EMC / FEC (7 : 3) with 3 mass% vinylene carbonate.

The material exhibits a first delithiation capacity of 1,620 mAh/g and a capacity retention of 83% after 150 cycles (C/2 charge / discharge). A comparative material (53.4 mass% silicon) exhibits 1,690 mAh/g delithiation capacity but a significantly lower and more variable capacity retention of 69-81% after 150 cycles.

A mixture of silicon-carbon composite active material, polyacrylonitrile (PAN, molecular weight: 80,000), single-walled carbon nanotubes (SWCNT), conductive flake graphite, and polyvinylidene fluoride (PVDF) was prepared in N-methyl-2-pyrrolidone (NMP). The slurry was coated on copper foil and dried (110°C, 12 h). This process results in negative electrodes with silicon-carbon composite material (78.5 mass%), PAN binder (13.5 mass%), SWCNT (0.5 mass%), conductive graphite (6.5 mass%), and PVDF (1.0 mass%). The drying temperature (110°C) ensured no nitrile group modification (no cyclization) in the PAN binder occurred.

Pouch cells were assembled with these negative electrodes paired against NMC₈₁₁ positive electrodes (3.1 mAh/cm², N/P ratio: 2.5). A carbonate-based electrolyte (1.2 M LiPF₆) was used.

In full cells, the material with unmodified PAN binder exhibits a first cycle efficiency of 89.4%, a cathode utilization of 95.4%, and a cycle life exceeding 1,300 cycles to reach 80% of initial discharge capacity (0.5 C charge / 0.5 C discharge, voltage range: 2.8-4.15 V, 25°C), as compared to 82.8%, 89.7%, and 1,100 cycles for comparative cells with fully cyclized PAN binder (100% nitrile group modification achieved through heat treatment at 330°C, 1.7°C/min ramp, 4 h hold).

A high-nickel Ni_0.89Co_0.04Mn_0.07(OH)₂ precursor with center-concentrated buffer pores was synthesized. Polypropylene particles (3 μm diameter) were added to a mixed metal sulfate solution (Ni : Co : Mn molar ratio of 0.89 : 0.04 : 0.07, 2.0 M, 50°C). The solution was stirred at 400 rpm while sodium hydroxide was added to maintain pH at 11.5-11.6, forming precursor seeds. The pH was decreased stepwise to 11.0-11.2, 10.7-10.9, and 10.3-10.5 while stirring speed increased to 1,000 rpm (5 h).

The dried precursor exhibits secondary particles (≈12 μm) with polypropylene concentrated in the core region. The precursor was mixed with lithium hydroxide (Li : transition metal molar ratio of 1.03 : 1) and sintered (5°C/min to 750°C, 17 h) to obtain LiNi_0.89Co_0.04Mn_0.07O₂.

During sintering, polypropylene decomposes to form buffer pores (≈3 μm) concentrated in the particle center (see Figure). Primary particles in the outer region exhibit radial crystalline structure oriented from center to surface.

In half-cells (lithium metal negative electrode, 0.5 C charge / 1 C discharge, 45°C), the material exhibits a discharge capacity of 210 mAh/g and capacity retention of 96.3% after 50 cycles, as compared to 210 mAh/g and 92.1% for material without buffer pores. The material exhibits 3.38 vol% of particles <1 μm after pressing, as compared to 5.71 vol% for comparative material.

Li₂CO₃, MnCO₃, FePO₄, NH₄H₂PO₄, and doping element sources (Al(OH)₃, H₃BO₃, MgO, Co(OH)₂) were mixed with Li : Mn : Fe molar ratio of 1 : 0.30000 : 0.70000. Sucrose (5 mass%) was added. The mixture was wet-milled with water (20 mass% solid content) to form a slurry (D₅₀ : 100 nm), followed by spray drying (inlet temperature : 230°C, outlet temperature : 95°C) and calcination (750°C, 8 h, nitrogen atmosphere) to obtain a lithium manganese iron phosphate compound with carbon coating.

Two compositions were synthesized. Example 1 comprises LiMn_0.29760Fe_0.69440Al_0.00400Mg_0.00400P_0.99800B_0.00200O₄ with Al (650 ppm), Mg (580 ppm), and B (130 ppm). Example 2 comprises LiMn_0.29700Fe_0.69300Al_0.00400Co_0.00200Mg_0.00400PO₄ with Al (650 ppm), Mg (580 ppm), and Co (700 ppm). Both materials exhibit manganese content of ≈30 mol% (excluding lithium) and include at least three doping elements from Al, B, Co, Mg, and Ni.

The materials exhibit average particle size (D₅₀) of 0.45-0.65 μm and crystallite size of 116-117 nm. In half-cell tests (45°C, 0.5 C charge to 4.25 V, 1.0 C discharge to 2.5 V), Example 1 exhibits capacity retention of 99.7% after 30 cycles, while Example 2 exhibits capacity retention of 99.5% after 30 cycles, as compared to 98.7-99.2% for comparative materials with fewer doping elements or improper manganese content.

Aluminum chloride solution (0.1 mol/L) was mixed with transition metal sulfate solution (Ni : Co : Mn = 88 : 5 : 7, 1.5 mol/L), adjusted to pH 11.0±0.5, and stirred (200 rpm, 20 min). The solution was atomized and fed into a spray pyrolysis tower (2 L/min, 200°C inlet, 400°C middle, 150°C outlet) to obtain Al-doped transition metal oxide powder.

The powder was mixed with lithium carbonate (Li to transition metal ratio 1.04) and sintered (500°C, 2 h then 740°C, 8 h). The material was mixed with nano-ZrO₂ (4,000 ppm) and calcined (800°C, 10 h).

The material exhibits Al enrichment x = 26% and depletion y = 36% by SEM-EDS mapping (see Figure), with Al >40 at% as enriched and <20 at% as depleted. The XRD 104 peak at 2θ = 44.38° indicates expanded interlayer spacing versus mechanically mixed materials (44.5°).

In half-cells, the material exhibits discharge capacity of 216 mAh/g (0.1 C, 25°C, 3.0-4.3 V vs. Li⁺/Li), first cycle efficiency of 90.6%, and capacity retention after 50 cycles of 92.3%, compared to 215 mAh/g, 88.8%, and 89.5% for mechanically mixed comparative material. DC resistance is 15 Ω and electrode expansion is 0.43%, versus 25 Ω and 1.15% for the comparative material.

A modified ionomer was developed for polymer electrolyte membrane fuel cell (PEMFC) cathode catalyst layers with enhanced oxygen transportability.

The ionomer comprises perfluorocarbon sulfonic acid polymer (Nafion EW : 1100) with sulfonic acid functional groups. A modifying layer containing 1,3,5-triazine forms ionic bonds with the acidic functional groups on the ionomer surface.

The ionomer material and modifier containing 1,3,5-triazine were mixed in water/ethanol solvent using an ultrasonic homogenizer and stirrer (15 min). The 1,3,5-triazine content was 3 mass% relative to total ionomer mass, corresponding to 34 mol% relative to acidic functional groups.

The modified ionomer was combined with platinum catalyst (48-50 mass% Pt on acetylene black support) to prepare cathode catalyst ink. The ink was coated onto polytetrafluoroethylene (PTFE) substrate and dried to form a catalyst layer (5-30 μm thickness, 0.1-0.6 mg-Pt/cm²). Membrane electrode assemblies (MEA) were fabricated using Nafion NR211 electrolyte membrane.

Performance testing (80°C, 80% relative humidity, 3.2 A/cm²) exhibits a cell voltage improvement of 64 mV as compared to unmodified ionomer MEA (absolute cell voltages were not disclosed). The electrode catalyst layer exhibits proton transport resistance of 0.043 Ω·cm² and oxygen diffusion resistance of 13 s/m, as compared to 0.062 Ω·cm² and 15 s/m for unmodified ionomer.