Triweekly Patent Update – Free Version

A solid-state battery incorporates a high-entropy oxyhalide solid electrolyte as an additive within the positive active material layer, paired with a high-voltage positive electrode charged to a cutoff of at least 4.3 V. Combining several cations of differing valence raises the lattice disorder and oxidative stability of the electrolyte, improving Li⁺ transport and interfacial compatibility with the positive electrode during high-voltage cycling.

The electrolyte follows the composition Li_3-2a-bA_aB_bC_cD_dE_eO_nCl_6-m-2nF_m, where A is a pentavalent metal (Ta, Nb, or V), B a tetravalent metal (Zr or Hf), and C, D, and E are three independent trivalent metals, with oxygen and fluorine partially replacing chlorine. In the worked embodiment Li_1.4Ta_0.5Zr_0.3In_0.1Y_0.1Er_0.1O_0.5Cl_4.9F_0.1, precursor lithium salts and metal chlorides (TaCl₅, ZrCl₄, InCl₃, YCl₃, ErCl₃) were ball-milled (500 rpm, 20 h) and annealed (200°C, 5 h, argon), giving particles of 0.3–5.2 μm. This electrolyte was blended with an LiNi_0.83Co_0.07Mn_0.08O₂ (Ni83) cathode and vapor-grown carbon fiber (70 : 27 : 3 by mass) and assembled against a Li-In electrode with a Li₆PS₅Cl sulfide separator layer.

Cells were cycled at 25°C between 2.8–4.8 V (vs. Li⁺/Li) after 0.1 C formation, then at 0.33 C. The Ni83 cell using Li_1.4Ta_0.5Zr_0.3In_0.1Y_0.1Er_0.1O_0.5Cl_4.9F_0.1 as the cathode-layer additive exhibits a 50-cycle capacity retention of 98.79%, compared to 89.83% for an otherwise identical cell using conventional oxyhalide LiTaOCl₄ and 90.17% for conventional halide LiTaCl₆. No ionic conductivity data was identified.

A dry-processed negative electrode plate blends three engineered active materials, each addressing a distinct limitation: a low-orientation natural graphite for fast charging, artificial graphite for cycle life, and a silicon-carbon composite for volumetric capacity.

The natural graphite was prepared by crushing flake graphite into primary particles (major axis 30 μm), folding them into small secondary particles (D₅₀ 7 μm), coating with amorphous carbon (graphite : carbon = 90 : 10 by mass), and heat-treating at 3,000°C. It exhibits an orientation degree of 60 – the XRD intensity ratio I(002)/I(110), below the specified ≤90 – and a d₀₀₂ spacing of 3.3569 Å. The artificial graphite is spherical (D₅₀ 15 μm).

The silicon-carbon composite is a metallurgical, top-down material rather than a silane-deposited one: micrometer-scale silicon particles (≈8 μm) were ball-milled into silicon nanoparticles (D₅₀ 100 nm), spray-dried with a stearic-acid dispersant into porous secondary aggregates (D₅₀ 7 μm), combined with petroleum pitch (silicon : carbon = 60 : 40 by mass), cold-isostatic-pressed at 10 MPa, and carbonized at 1,000°C under nitrogen — converting the pitch to a ≈30 nm soft-carbon coating over the aggregate surface and through its interparticle pores. The finished coated particle (D₅₀ 8.2 μm; D₁₀ 4.7 μm, D₉₀ 13.7 μm) exhibits a sphericity of 0.98 and a mesopore-to-total-pore-volume ratio of 68%. The three actives were blended at 47 : 47 : 6 by mass, dry-mixed with 1.5 mass% polytetrafluoroethylene (PTFE) binder, and calendered into a 150 μm solvent-free electrode.

In lithium half-cells, the electrode exhibits a discharge capacity of 435 mAh/g and a first-cycle efficiency of 91% (0.1 C). At cell level, it exhibits an energy density of 760 Wh/L, a fast-charge cycle life of 1,500 cycles (cycles to 80% state of health under repeated 8–80% state-of-charge charging), and an electrode swelling of 5% after 50 cycles (0.5 C / 0.5 C, 45°C), as compared to 760 Wh/L / 750 cycles / 8% for a comparative whose natural graphite has an orientation degree of 110 (outside ≤90), and 740 Wh/L / 800 cycles / 10% for a comparative using silicon oxide in place of the silicon-carbon composite.

A Fe_0.45Mn_0.55(OH)₂ precursor was prepared by co-precipitation, mixed with LiOH·H₂O at a lithium-excess Li/(Fe+Mn) molar ratio of 1.55, and sintered (800°C, air) to yield the lithium-excess oxide Li_1.22Fe_0.35Mn_0.43O₂ (spherical secondary particles, D50 8 μm; primary particle 0.8 μm), without carbon coating.

The material has a structure combining layered domains with cation-disordered rocksalt domains, characterized by an I(003)/I(104) ratio of 0.94 and a single broad superstructure peak. The co-precipitated powder has a sphericity of 0.91, a tap density of 2.23 g/cm³, and a pellet density of 2.81 g/cm³.

In coin half-cells, the material exhibits a 0.1 C initial discharge capacity of 162 mAh/g (2.0–4.4 V vs. Li⁺/Li, 25°C), a capacity retention of 96.4% after 50 cycles (2.0–4.65 V), a rate capability (1 C/0.1 C) of 89%, and a volumetric energy density of 563 Wh/L, as compared to 154 mAh/g and 432 Wh/L for conventional carbon-coated olivine LiFe_0.4Mn_0.6PO₄. Materials with Fe/Me above the range (0.5) or below it (0.1) gave 521 and 487 Wh/L, the low-iron material also showing a reduced rate capability of 74.3%.

A process for manufacturing catalyst-coated polymer electrolyte membranes (CCMs) by sequential additive-layer deposition was developed for proton exchange membrane fuel cell (PEMFC) and water electrolyser applications, eliminating membrane ionomer penetration into the underlying catalyst layer during coating.

A catalyst composition of a noble metal-containing electrocatalyst (such as platinum on carbon) and a catalyst layer sulfonic acid ionomer – characterised by its alpha transition temperature Tα – is applied to a support substrate and heat treated at Tα + 40°C to Tα + 120°C (preferably Tα + 40°C to Tα + 80°C) for 10 seconds to 20 minutes before the membrane ionomer is dispersion-cast directly onto it (top Figure). Below Tα + 40°C the membrane ionomer penetrates the catalyst layer; above Tα + 120°C the ionomer structure can be damaged.

Using a Pt/C catalyst layer with a short side chain perfluorosulfonic acid (PFSA) ionomer (Aquivion D79-25BS, Tα 100°C), the average membrane ionomer penetration measured by optical microscopy fell from ≈21% at 80°C (Tα − 20°C) to ≈4% at 120°C (Tα + 20°C), with no penetration at 160°C (Tα + 60°C) (bottom Figure). The reduction held across platinum loadings of 0.05–0.08 mg/cm² and membrane ionomer dispersion solids of 10–19 mass%.

Top Figure: Additive-layer manufacturing sequence – (i) first catalyst layer patches (2) on support substrate (1); (ii) coating with a membrane ionomer dispersion, forming the first membrane layer (3); (iii) build-up of the polymer electrolyte membrane (4); (iv) optional second catalyst layer (5) applied to the opposite face
Bottom Figure: Average membrane ionomer penetration (%) versus catalyst layer peak heat-treatment temperature (80, 120, 160°C)