Triweekly Patent Update – Free Version

A solid-state lithium metal battery cell incorporates a poly(ionic liquid) layer between the solid electrolyte layer and the lithium metal anode. The layer combines a poly(ionic liquid) with a lithium salt to conduct Li⁺ across the interface while reducing side reactions between the lithium metal and the sulfide solid electrolyte and lowering dendrite-growth risk.

The interlayer comprises an acrylate-based imidazolium poly(ionic liquid) and LiTFSI at a monomer-to-salt molar ratio of 4 : 1, formed by in-situ thermal polymerization. A precursor solution of the imidazolium monomer and LiTFSI was combined with azobisisobutyronitrile (AIBN) initiator at 3 mass% of the monomer, drop-cast onto the Li₆PS₅Cl solid electrolyte pellet, and contacted with the lithium metal anode. The cell was polymerized under argon (60°C, 12 h), forming a 30 μm interlayer. The positive electrode comprises LiNbO₃-coated NCM811 with Li₆PS₅Cl, nitrile butadiene rubber (NBR) binder, and carbon black (70 : 27.5 : 1.5 : 1).

The poly(ionic liquid)-interlayer cell exhibits a first discharge capacity of 172 mAh/g, a first-cycle coulombic efficiency of 90.1%, and a 100-cycle capacity retention of 92% (0.33 C, 25°C, 5 MPa, 2.6–4.3 V), compared to 142 mAh/g, 74.3%, and 30.2% for a cell without the interlayer. Incorporating a non-polymerized ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide) into the layer raises these values to 175 mAh/g, 92.1%, and 94%. No interlayer ionic conductivity data was identified.

A core-shell silicon-carbon nanowire anode material with a crystalline silicon core and an amorphous carbon shell was developed, with nanowire growth and carbon coating completed sequentially in a single high-temperature vacuum furnace. Silicon dioxide (SiO₂) powder and charcoal powder serve as the silicon and reductant sources, and polyimide serves as the carbon shell precursor.

SiO₂ powder (300 mesh) and charcoal powder were mixed at a molar ratio of 1 : 3 with anhydrous ethanol and pressed at 4 MPa into a compact. The compact was purged with nitrogen, evacuated to −10 Pa, and heated at 10°C/min to 1,100°C with a 240 min hold. At high temperature the charcoal reduces SiO₂ to gaseous SiO and carbon monoxide, which migrate to the furnace condensation zone where crystalline silicon nanowires grow.

The furnace was cooled to 300°C, and vaporized polyimide precursor was carried into the chamber by argon (60 sccm) and deposited onto the nanowires for 60 min. After stopping the precursor and purging, the chamber was heated to 800°C and held for 90 min to decompose and carbonize the polymer into the amorphous carbon shell. The resulting material exhibits a silicon content of 50 mass%, a silicon core diameter of 10–20 nm, and a carbon shell thickness of 15 nm.

In half-cells, the material exhibits a first-cycle charge capacity of 1,650 mAh/g, a first-cycle efficiency of 89.5%, and a capacity retention of 89.2% after 50 cycles, as compared to 2,300 mAh/g, 70%, and 45% for a comparative silicon nanowire material prepared without the carbon shell.

Figure: HR-TEM (high-resolution transmission electron microscopy) image of the core-shell silicon-carbon nanowire (Example 1), showing the crystalline silicon core enclosed by the amorphous carbon layer (scale bar: 5 nm).

A polycrystalline NMC precursor (D₅₀: 10–20 μm) was mixed by low-shear mixing with unmilled lithium hydroxide (D₅₀ ≥ 150 μm), avoiding the lithium-source milling used in prior work. The mixture was preheated (200–300°C) to remove water, heated at a homogenizing temperature (250–500°C) below the sintering temperature, and sintered (700–900°C, 8–14 h).

At the homogenizing temperature, the large lithium hydroxide particles melt and coat the precursor, which the patent identifies as the source of uniform lithiation without prior milling. Thermogravimetric and differential scanning calorimetry confirm lithium hydroxide melting at 400–490°C. SEM shows uniform NMC after homogenization with unmilled lithium hydroxide.

In assembled cells (0.05 C, 2.7–4.3 V), the homogenized material exhibits a 0.05 C discharge capacity of 224.5 mAh/g, a 0.33 C discharge capacity of 207 mAh/g, and a 1.0 C charge capacity of 198.2 mAh/g, as compared to 224.6, 207, and 198.4 mAh/g for material from milled lithium hydroxide.

Figure: SEM image of the NMC material after homogenization with unmilled lithium hydroxide, showing uniform morphology.

A carbon nitride (CN) coated, nitrogen-doped platinum–nickel oxygen reduction reaction (ORR) catalyst was developed for proton exchange membrane fuel cell (PEMFC) cathodes, addressing the poor durability of platinum-alloy catalysts whose transition metal leaches under acidic conditions and contaminates the membrane.

The catalyst has a core–shell structure: a nitrogen-doped Pt/Ni core enclosed by a thin platinum shell (1–4 Pt monolayers) and an exterior carbon nitride layer, loaded on a mesoporous carbon support (MPC-HPDA; pores mostly 2.0–8.0 nm). The coating is CN_x with an N : C molar ratio of 0.1 ≤ x ≤ 4; nanoparticle average diameter is 1.5–8.0 nm.

CN_x-PtNiN was synthesized by dispersing platinum and nickel acetylacetonates, urea, and the mesoporous carbon in acetone, then annealing under flowing argon at ~500°C for ~2 h at a nickel : urea ratio of 1 : 5 to 1 : 10. X-ray diffraction gave particle sizes of 1.8–3.0 nm (samples S1–S5), and X-ray photoelectron spectroscopy (XPS) detected C–N bonds without C–C bonds, confirming the carbon nitride coating (top Figure).

Nitrogen doping is proposed to modify the platinum electronic structure, while the carbon nitride coating is believed to protect the nanoparticles against agglomeration, dissolution, and ionomer poisoning. After an accelerated stress test (10,000 square-wave cycles, 0.6–1.0 V), CN_x-PtNiN showed 14% higher mass activity retention than an uncoated PtNiN comparative (Sample S6, annealed under NH₃ without urea) (bottom Figure). No absolute mass activity or polarization-curve data are reported.

CN_x-PtNiN: Carbon nitride coated nitrogen-doped PtNi catalyst
PtNiN: Uncoated nitrogen-doped PtNi comparative catalyst (Sample S6)
Top Figure: XPS C 1s spectrum (x-axis: binding energy [eV]; y-axis: intensity [a.u.]) showing a C–N peak without a C–C peak, confirming the carbon nitride coating
Bottom Figure: Mass activity retention (%) after accelerated stress testing for uncoated PtNiN versus CN_x-PtNiN (14% improvement)