Triweekly Patent Update – Free Version

A dry-process method achieves solid electrolyte membranes at ≤10 μm through simultaneous biaxial stretching of a PVDF-HFP-based composite, enabling thinner membranes than conventional dry calendering approaches.

First, polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) and polyethylene oxide (PEO) were blended with dibutyl phthalate (DBP) plasticizer (160°C, 35 r/min); LLZO (Li_6.25La₃Zr₂Al_0.25O₁₂, garnet-type) and LATP (NASICON-type oxide) particles were then incorporated. Second, the mixture was melt-extruded (90–150°C zones, 400 rpm), T-die cast, and calendered (90°C, 50 MPa, 15 min) to a 100 μm primary film. Third, the film was simultaneously biaxially stretched (75°C, 350 mm/min, 3× in each direction) and heat-set under tension (100°C, 2 min). Fourth, supercritical CO₂ (45°C, 20 MPa, 4 h) removed DBP, yielding a porous 10 μm membrane.

The membrane was hot-laminated onto an LMO : NCM (7 : 3) positive electrode (130°C, 60 N/mm) and assembled into hybrid liquid electrolyte cells (wound, aluminum housing) with graphite negative electrodes and PE separators. Cells exhibit rate capacity retentions of 98.0% at 2 C and 98.7% at 3 C, and 91.6% cycle retention after 1000 cycles (1 C/1 C, 25°C). Cell energy is 304.69 Wh at discharge DCR of 0.443 mΩ, versus 285.70 Wh and 1.256 mΩ for cells with a polymer electrolyte membrane. Needle penetration tests confirm no ignition (temperature rise <90°C), versus thermal runaway (>700°C) in comparative liquid electrolyte cells with PE separator only.

A porous carbon matrix (BET: 1,940 m²/g, pore volume: 1.00 cm³/g, D₅₀: 9 μm) was exposed to humid air to introduce hydroxyl (OH) groups to active sites, then heated under nitrogen until CO gas was detected at ≈7,500 ppm in the exhaust. With CO still present, monosilane (SiH₄) was introduced at 350–360°C and 50 kPa, depositing amorphous low-valence nano-silicon oxide (SiO_x, 0–3 valence composite) partially bonded to the carbon's oxygen atoms.

After cooling, gradual oxidation with 1% O₂/N₂ over 48 h raised the bulk oxygen content to 2.5 mass%. Acetylene CVD at 580°C and 10 kPa for 8 h formed a carbon coating, generating Si–C bonds at dangling bond sites and C=O/C–O bonds at the oxide–carbon interface. The 0-valence Si grain size is 0.8 nm (XRD); the surface layer (0–50 nm) exhibits a Si phase structure distinct from the bulk interior.

In half-cells (0.03 C), the anode active material exhibits a capacity of 1,880 mAh/g and a first cycle efficiency of 88%, as compared to 1,825 mAh/g and 85% for material deposited without CO co-presence during silane introduction (bulk phase: Si⁰⁺ + SiO₂). In full cells (0.7 C charge / 0.5 C discharge), 1,000-cycle retention is 80%, 4 C charge retention is 80% at 500 cycles, and slurry gas generation is 0.1 cc/g (60°C, 1 week), as compared to 72% retention, lithium plating (metallic lithium deposition on the anode surface) at 4 C / 500 cycles, and 2.1 cc/g for the comparative material.

A Ni_0.93Co_0.03Mn_0.04(OH)₂ precursor, LiOH, and ZrO₂ (molar ratio 1 : 1.05 : 0.001) were mixed in a high-speed mixer (1800 rpm, 30 min), sintered in ≥96% O₂ (3°C/min to 500°C for 2 h, then 740°C for 12 h), washed with deionized water (8°C, solid-liquid ratio 1.0, 700 rpm, 3 min), and vacuum-dried (160°C, 6 h) to yield matrix Li_1.01Ni_0.929Co_0.03Mn_0.04Zr_0.001O₂.

The matrix was mixed with Sb₂O₅ and PVDF (mass ratio 1 : 0.0027 : 0.0017) in a high-speed mixer (1800 rpm, 30 min), then sintered in O₂ (3°C/min) in three stages: 200°C for 2 h, 400°C for 4 h, and 600°C for 8 h, followed by natural cooling and sieving. Residual surface Li₂CO₃ reacts with Sb₂O₅ and PVDF to form a composite solid electrolyte coating comprising LiSbO₃, LiSbF₆, and Li₂CO₃.

The LiSbO₃ : LiSbF₆ : Li₂CO₃ coating (molar ratio 3 : 3.7 : 25.9, 0.86 mass%) also covers primary particle surfaces, as confirmed by EPMA mapping; the primary particle size is 190 nm and the residual lithium is 1114 ppm. In coin half-cells (4.35–3.0 V vs. Li⁺/Li), the material exhibits a 0.1 C discharge capacity of 234.3 mAh/g, a first coulombic efficiency of 94.2%, a rate capability of 92.2%, a DC internal resistance (DCR) of 15.8 Ω, and a capacity retention of 94.1% after 50 cycles at 45°C, as compared to 226.4 mAh/g, 91.5%, 89.6%, 25.3 Ω, and 85.1%, respectively, for the water-washed matrix without the solid electrolyte coating.

A post-treatment method for platinum alloy catalyst material (Pt_xM, M = Co, Ni, Fe, Cu; nanoparticle mean diameter <10 nm) was developed for PEMFC (proton exchange membrane fuel cell) cathodes, targeting pre-emptive extraction of transition metal from deeper particle layers to reduce in-operando contamination.

The catalyst powder is suspended in an acid solvent (nitric, sulfuric, hydrochloric, acetic, and/or formic acid) in a stirred flask at 5–150°C (preferably 25–80°C). O₂-rich gas (G1, 0.01–100 vol.% O₂) and H₂-rich gas (G2, 1–100 vol.% H₂), each with N₂ or Ar balance, are fed alternately through a glass frit and microcontroller-operated dosing valves at 1–10 bar; cycle duration 5 s to 24 h (preferably 30 s to 30 min). An optional post-annealing step can promote crystal lattice rearrangement.

The alternating gas atmosphere induces chemical potential cycles differing by ≥0.5 V (preferably ≥1 V) on the catalyst surface, replicating in-cell voltage cycling to dissolve transition metal from particle layers that near-surface dealloying methods cannot reach. The O₂/H₂ gas-cycle post-treated catalyst (6) deliberately releases more transition metal during post-treatment than the untreated reference (6_Ref): metal extracted at this stage is no longer available to contaminate the ionomer during cell operation, reducing proton conductivity losses at high current densities (>1000 mA/cm²), where the treated catalyst demonstrates markedly higher cell voltage (Figure). No specific transition metal M is identified for the experimental data shown.

6: Post-treated platinum alloy catalyst material
6_Ref: Untreated reference platinum alloy catalyst material
Left chart y-axis (0–2): Normalized transition metal release (arbitrary units)
Right chart axes: Cell voltage U [V] vs. current density I [mA cm^-2]