Triweekly Patent Update – Free Version

An all-solid-state secondary battery was developed featuring an intermediate layer between the negative electrode and solid electrolyte layer to suppress crack formation during initial cycling.

The intermediate layer comprises fibrillated PTFE (polytetrafluoroethylene) and Li₆PS₅Cl (argyrodite-type sulfide electrolyte) in a 5 : 95 mass ratio. The mixture was rolled at 23°C using 100 mm diameter rollers to form a 0.30 mm thick sheet (subsequently compressed during final assembly at 6000 kgf/cm²), with the rolling process inducing fibrillation of PTFE particles into fibrous structures.

The negative electrode comprises TiNb₂O₇, graphene, carbon nanotubes, PTFE particles, and Li₆PS₅Cl in a 68 : 8.8 : 0.2 : 2 : 21 mass ratio. The positive electrode contains LiCoO₂ coated with a LiNbO₃ reaction inhibition layer (2 mass% loading), mixed with vapor-grown carbon fibers and Li₆PS₅Cl (66 : 4 : 30 ratio).

The solid electrolyte layer consists of Li₆PS₅Cl pressed at 1000 kgf/cm². The complete assembly was formed by sequential pressing of positive electrode, solid electrolyte layer, intermediate layer, and negative electrode in a powder molding die (6000 kgf/cm², room temperature).

The battery exhibits a first-cycle coulombic efficiency of 84.5% (0.1 C charge to 3.2 V with constant voltage cutoff at 0.01 C, followed by 0.1 C discharge, 25°C). Comparative cells without the intermediate layer show significantly lower efficiency (79.3%). No cycle life metrics were identified.

Phenolic resin was heat-treated in two stages to prepare a carbon precursor. The resin was heated to 300°C at 10°C/min, held for 1 h, then heated to 500°C at 1°C/min, and held for 1 h.

The carbon precursor was mixed with KOH activator (1 : 3 mass ratio). Steam (2 mL/min flow rate) was introduced while heating to 600°C at 5°C/min for activation (8 h). The material was washed with 1 M HCl, rinsed with water, and dried, yielding porous carbon.

The porous carbon exhibits a symmetric vacancy defect signal peak in its EPR (electron paramagnetic resonance) spectrum with a linewidth ΔH of 50.4 G, intensity of 2.36 × 10⁴ a.u., and g-factor of 2.003. The material exhibits a micropore content of 92.29%, mesopore content of 7.71%, and total pore volume of 0.90 cm³/g.

The porous carbon was placed in a fluidized bed CVD reactor. Nitrogen carrier gas (20 L/min) and monosilane (5 L/min) were introduced at 550°C under 5 kPa pressure for silicon deposition (8 h).

After purging the reactor with nitrogen, a carbon coating was deposited by introducing carbon source gas (4 L/min) and nitrogen (10 L/min) at 500°C for 2 h, yielding the silicon-carbon composite material.

The resulting material exhibits a Si content of ≈50 mass%, a powder resistivity of ≈2 Ω·cm at 30 MPa, and a D_v50 of 5-10 μm.

In half-cells, the material exhibits a discharge capacity of 2,095 mAh/g, a first cycle efficiency of 93%, and a capacity retention of 91% after 100 cycles (1 C charge / discharge), as compared to 1,613 mAh/g, 85%, and 87% for comparative materials prepared with excessive activation (EPR linewidth: 86.5 G, intensity: 8.96 × 10⁵ a.u., g-factor: 1.998, indicating excessive vacancy defect concentration), and 1,457 mAh/g, 81%, and 89% for materials prepared without controlled heat treatment (EPR linewidth: 15.7 G, intensity: 1.35 × 10³ a.u., indicating insufficient vacancy defects).

Ni_0.75Co_0.07Mn_0.18(OH)₂ precursor was mixed with lithium sources (Li₂CO₃ and LiOH at 7 : 1 molar ratio, Li to transition metal molar ratio: 1.4) and SrO (Sr content: 2000 ppm), followed by sintering (920°C, 18 h, oxygen atmosphere).

The base material was mixed with TiO₂ (Ti content: 12000 ppm) and stirred in air (60°C material temperature, 20-30°C ambient, 60-80% relative humidity, 300 rpm, 3 h) to convert unstable Li₂O and excess LiOH into Li₂CO₃, followed by sintering (650°C, 10 h, air atmosphere).

The resulting single-crystal material exhibits the composition Li_1.16Ni_0.75Co_0.07Mn_0.18Sr_0.002Ti_0.018O_2.09 with surface nanoparticles of Ti_0.049Li_1.9CO₃ (9.051 mass%) and residual LiOH (0.003 mass%). Ti is distributed both in the surface carbonate coating and within the bulk material. The Ti-doped carbonate decomposes irreversibly below 4.45 V during first charge, compensating for lithium loss at the negative electrode. The material exhibits a D₅₀ of 2.9 μm, SPAN of 1.10, and electronic conductivity of 0.029 S/cm.

In half-cells, the material exhibits a 0.1 C discharge capacity of 214.7 mAh/g , a 2 C / 0.2 C capacity retention of 92.3%, and a capacity retention after 50 cycles of 96.4% (1 C charge / discharge, 3.0-4.45 V vs. Li⁺/Li, 25°C).

A mesoporous Fe-N-C single atom catalyst was synthesized for polymer electrolyte membrane fuel cells (PEMFC) using a zeolitic imidazolate framework (ZIF-8) precursor with controlled pore architecture.

Zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) was dissolved in water (46 mM) to prepare the first precursor solution. A hydrophilic block copolymer (PEO-b-PS, polyethylene oxide-b-polystyrene) was dissolved in tetrahydrofuran to prepare the second precursor solution. The organic ligand 2-methylimidazole was dissolved in water (400 mM) to prepare the ligand solution.

The three solutions were mixed via stirring (1,000 rpm) at ambient temperature to form mesoporous ZIF-8. The material was separated via centrifugation, washed with methanol, and vacuum-dried (60°C, 12 h). The dried precursor was subjected to thermal activation in a tube furnace (900-1,100°C, 1.5-2.5 h, no atmosphere details provided) to form the Fe-N-C catalyst with edge-hosted Fe-N₄ active sites.

The resulting catalyst exhibits mesopores with diameters of 5-50 nm, with a predominant pore size of approximately 10 nm confirmed through nitrogen adsorption-desorption analysis. X-ray absorption spectroscopy confirms formation of distorted Fe-N₄ single atom active sites without Fe-Fe bonding, indicating atomically dispersed iron.

Electrochemical testing in oxygen-saturated 0.5 M H₂SO₄ solution demonstrates a half-wave potential (E_1/2) of 0.80 V vs. RHE (reversible hydrogen electrode), representing a 20 mV improvement compared to non-mesoporous Fe-N-C catalyst (0.78 V). The optimized catalyst prepared at 900°C exhibits minimal H₂O₂ selectivity (1%), indicating a nearly ideal four-electron oxygen reduction pathway that directly produces water while avoiding peroxide intermediates that cause catalyst degradation via Fenton reactions.

The Fe utilization rate increases from 20% to 40% due to mesopore-enabled exposure of Fe active sites at carbon edge positions, where geometric distortion of Fe-N₄ sites optimizes oxygen intermediate binding energies. Durability testing at 0.7 V for 50 h shows 70% current density retention for the catalyst activated at 1,000°C.

D-Fe-N-C: Fe-doped ZIF-8 without mesopores (Comparative Example 1)
D-Meso-Fe-N-C: Fe-doped mesoporous ZIF-8 (Comparative Example 2)
Meso-Fe-N-C: Mesoporous ZIF-8 with edge-hosted Fe sites (Example)
E_1/2: Half-wave potential
E_onset: Onset potential
Utilization rate: Percentage of total Fe atoms serving as active sites