Triweekly Patent Update – Free Version

A solid electrolyte layer for sulfide-based solid-state batteries incorporates an ionic plastic crystal that reduces its shear strength, measured via Surface And Interfacial Cutting Analysis (SAICAS), to 15–70 MPa, enabling stable cycling under low confining pressure (≤1.0 MPa).

The best-performing example combines Li₆PS₅Cl, PVDF binder, and 5-azoniaspiro[4,4]nonane 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide (SBPCFSI, top Figure; with 10 mol% LiTFSI) at a 96.5 : 1 : 2.5 mass ratio. A slurry in xylene / isobutyl isobutyrate was blade-coated onto a PET sheet, dried (40°C, 12 h vacuum), and isostatically pressed (490 MPa).

Full cells with a Li₂O-ZrO₂-coated LiNi_0.8Co_0.15Mn_0.05O₂ positive electrode (impregnated with SBPCFSI in dichloromethane) and a plating-type Ag / carbon black negative electrode were cycled at 0.3 MPa confining pressure (25°C, 2.5–4.25 V). Example 1 exhibits a shear strength of 49.0 MPa, a 100-cycle capacity retention of 93.2%, and an average coulombic efficiency of 99.9%, compared to 88.8 MPa, 10.1%, and 96.8% for a Li₆PS₅Cl / PVDF layer without plastic crystal. Replacing SBPCFSI with succinonitrile + 5 mol% LiTFSI (Example 12) achieves comparable performance (49.7 MPa, 93.1%).

Top Figure: Structures of the SBPCFSI cation (5-azoniaspiro[4,4]nonane, SBP⁺) and anion (1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide, CFSI^-).
Bottom Figure: 100-cycle capacity retention as a function of deemed shear strength for solid electrolyte layers of varying composition.
X-axis: 간주 전단강도 (MPa) = deemed shear strength (MPa); Y-axis: 100 사이클 용량 유지율 (%) = 100-cycle capacity retention (%)
실시예: Example
비교예: Comparative example

Porous polydisperse silica (SiO₂) microspheres (D₅₀: 2–4 μm) served as feedstock for a silane-free route to silicon-carbon composite anode materials. The microspheres were dehydrated at 600°C for 1 h under N₂.

Magnesiothermic reduction was carried out with a remote Mg source (≈150 μm Mg particles placed in a lower compartment and separated from the silica feedstock by a stainless steel mesh) at 600°C and ≈2 kPa for 8 h in Ar, forming intermediate particles comprising Si, MgO, and residual Mg₂Si. A silicide-removal anneal at 650°C and ≈0.13 kPa for 6 h in Ar decomposed the Mg₂Si.

A carbon termination layer was deposited by CVD (chemical vapor deposition) of propylene (33 vol% in N₂) at 630°C for 1 h to passivate the freshly reduced Si surfaces. The MgO byproduct was selectively removed by stirring in 1 M HCl for 60 min, and a final carbon sealing layer was deposited by CVD of propylene (33 vol% in N₂) at 630°C for 26 h to reduce the specific surface area.

In lithium-ion half-cells, the material exhibits a Si content of 65.2 mass%, a first cycle reversible capacity of 2,497 mAh/g, and a first cycle efficiency of 89.6%.

Figure: SEM (scanning electron microscope) micrograph at 50,000× magnification showing reduced Si particles dispersed within the carbon matrix of the silicon-carbon composite (scale bar: 200 nm).

A Ni_0.88Co_0.09Mn_0.03(OH)₂ precursor was synthesized by co-precipitation (NiSO₄, CoSO₄, MnSO₄; NaOH precipitant; transition metal : NaOH = 1 : 2 mol/mol). Mixing with LiOH in a dry high-speed mixer and two-step calcination (2°C/min to 850°C, 7 h; then 700°C, 12 h) yielded single-particle LiNi_0.88Co_0.09Mn_0.03O₂ (D50: 3 μm). Single-step calcination (2°C/min to 760°C, O₂ at 10 mL/min) of the same precursor mixed with LiOH yielded secondary-particle LiNi_0.88Co_0.09Mn_0.03O₂ (D50: 13 μm).

LiMn_0.60Fe_0.40PO₄ (irregularly-shaped secondary particles, D50: 1 μm) was synthesized by mixing FePO₄, Mn₂O₃, LiH₂PO₄, Li₂CO₃, and an additive in deionized water, followed by sand grinding, spray drying, first calcination (2°C/min to 850°C, N₂ at 10 mL/min), carbon source addition, grinding, spray drying, and second calcination (700°C).

The three fractions were dry-blended at 49 : 21 : 30 mass% (secondary-particle NMC : single-particle NMC : LMFP). In coin half-cells (4.3–2.0 V vs. Li⁺/Li, 25°C), the blend exhibits a volumetric energy density of 650 Wh/L (0.1 C) and a high-temperature cycle retention of 92.5% after 500 cycles (1 C / 1 C). In 30–50 Ah pouch full cells charged to 4.2 V and heated to 0 V in a 1000 L autoclave, the maximum autoclave pressure is 0.32 bar, as compared to 710 Wh/L, 75.5%, and 2.99 bar, respectively, for 100 mass% secondary-particle LiNi_0.88Co_0.10Mn_0.02O₂ without LMFP and without single-particle NMC.

A PEM (proton exchange membrane) of a PFSA (perfluorosulfonic acid) ionomer containing an MNFB (methoxy-nonafluorobutane) coated additive was developed for PEMFC (proton exchange membrane fuel cell) and water electrolyzer applications, targeting improved proton conductivity at intermediate and high relative humidity.

The additive — a Pt/C recombination catalyst or an inert particle (silica, carbon black, graphene, or carbon nanotubes; 20 nm–1 µm; specific surface area 10–1000 m²/g) — is wet-ground in methoxy-nonafluorobutane (NOVEC 7100 Engineering Fluid, 3M; 1–72 h), optionally with an alcohol, to coat the particle surfaces with 0.1–5 mass% MNFB (preferably 1–2 mass% of the MNFB + additive). The coated additive is filtered, dried (50–100°C, 5–30 min), and combined with a PFSA ionomer solution at a 1 : 10 to 1 : 2000 PFSA ionomer : coated additive weight ratio (preferred 1 : 100 to 1 : 300).

The dispersion is cast onto an expanded polytetrafluoroethylene (ePTFE) support membrane (1–10 µm) and dried at 60–180°C for 10–60 min; an optional second PFSA layer with coated additive is applied on the opposite ePTFE face. The preferred PEM comprises a 4–15 µm first PFSA layer, a 1–10 µm ePTFE reinforcement, and a 2–6 µm second PFSA layer (total 6–30 µm), with coated additive areal density of 5–100 µg/cm². Coated additive particles are dispersed throughout both PFSA layers, with the PFSA ionomer penetrating the ePTFE micropores (top Figure).

Four-probe EIS (electrochemical impedance spectroscopy) at 40–100% relative humidity shows that a PFSA membrane containing MNFB-coated Pt/C additive (A) achieves markedly higher in-plane proton conductivity than an otherwise identical membrane with unmodified Pt/C additive (B) at RH ≥ 50%, reaching ≈325 mS/cm at 100% RH versus ≈275 mS/cm for the unmodified reference (bottom Figure). Enhanced PFSA affinity for fluorocarbon molecules on the MNFB-coated additive surface is proposed to orient sulfonate ion clusters, improving proton transport.

A: PFSA membrane containing MNFB-coated Pt/C additive
B: PFSA membrane containing unmodified Pt/C additive (comparative)
Top Figure: Schematic cross-section of the PEM showing MNFB-coated additive particles (330) dispersed throughout the PFSA ionomer (302) first layer (322) and second layer (326), separated by an ePTFE reinforcement (312) whose micropores (310) are penetrated by ionomer; H⁺ transport direction indicated
Bottom Figure X-axis: Relative humidity (%)
Bottom Figure Y-axis: In-plane proton conductivity (mS/cm) measured by four-probe EIS