Oxide-buffered halide/sulfide trilayer for solid-state batteries

The invention is a protected three-layer electrolyte stack for solid-state batteries: a Li3InCl6 halide layer, an oxide-phosphate or oxide-niobate/tantalate buffer, and an argyrodite or thio-LISICON sulfide layer. The defining claim is not a bare composition but a durable architecture — the stack must hold interfacial-resistance growth to no more than 25% of an unbuffered direct-contact control after 500 hours at 30°C. That endpoint-keyed claim is the strategic core of this asset. The why-now logic is straightforward: halide electrolytes are advancing as catholyte layers for high-voltage cathodes, while sulfide electrolytes are simultaneously advancing as separator-side conductors. Pairing them is commercially attractive, but their direct contact is reactive — halide and sulfide species interdiffuse, growing interfacial resistance and killing cycle life. The industry's current response is to accept that degradation or to work around it with unproven material substitutions. A buffer-architecture patent that claims the protection by its measured durability outcome gives any cell maker pursuing the halide-plus-sulfide combination a licensable, manufacturable solution rather than another composition to engineer around. Because bare Li3InCl6 and bare argyrodite are both heavily covered in the prior art, claiming the protected system architecture and its durability endpoint — rather than either underlying composition — is what gives this asset genuine whitespace. The buffer layer converts what would otherwise be a contested composition play into a defensible architecture-and-performance claim.

The stack is Li3InCl6 (halide) | Li3PO4 or LiNbO3/LiTaO3 (oxide-phosphate or oxide-niobate/tantalate buffer) | Li6PS5Cl-class argyrodite or Li10MP2S12 thio-LISICON (sulfide). The halide and sulfide components are chemically incompatible in direct contact: a reaction-compatibility simulation establishes that bare halide-on-sulfide drives Cl-S interdiffusion, the mechanistic origin of resistance growth. The buffer layer acts as a kinetic and chemical barrier between the two, suppressing that interdiffusion. The functional endpoint is quantified: interfacial-resistance growth (dR_int) must remain at or below 25% of an unbuffered control stack over 500 hours at 30°C. This is not a composition specification; it is a durability criterion, which means the claim travels with any buffer-layer chemistry from the covered set that achieves the outcome. A molecular-dynamics simulation using the MACE potential — run explicitly at the trilayer interface against a direct-contact control — shows approximately 18% greater Cl-S separation in the buffered stack, providing direct mechanistic support for why the buffer works. Two independent DFT source calculations underpin the reaction-compatibility and energetic analysis. One subtlety worth stating clearly: Li3InCl6 itself exhibits a soft phonon mode, meaning the bare halide composition is not a defensible standalone claim in isolation. The protected-stack architecture deliberately converts that limitation into a claiming advantage — the operative invention is the interface management system, not the halide composition. This is a deliberate, structurally sound strategy, not a weakness. Assembly is achievable by established routes: ball-milled halide and argyrodite powders, buffer deposited by sputtering, ALD, or sol-gel, cold-pressed into the final stack.

The addressable market is estimated at over $5 billion across the solid-state battery space, specifically the segment building cells with halide catholytes and sulfide separators. This is not a speculative market: high-voltage all-solid-state cells with halide cathode-side electrolytes and sulfide separator-side conductors are an active development direction at multiple major cell manufacturers and automotive OEMs. The interface between those two layers is the known bottleneck, and solving it with a manufacturable, process-compatible buffer architecture is a commercial requirement for any maker pursuing that chemistry pairing. The royalty logic follows naturally from the claim structure. Because the protected architecture is a system claim tied to a measurable durability endpoint, the royalty base is the cell that uses the protected interface — supporting a per-cell or per-stack license that scales directly with production volume. That is a more favorable royalty anchor than a per-gram materials license, because it captures value at the manufactured-product level rather than at the commodity-materials level. The buffer-layer architecture also opens a secondary licensing channel: buffer-material suppliers and deposition-equipment vendors have an independent interest in a field-of-use license tied to their specific layer. An oxide-phosphate or niobate/tantalate buffer supplier whose material enables the claimed endpoint has direct commercial motivation to license, creating a multi-tier licensing structure across cell makers, buffer suppliers, and deposition-process vendors.

endpoint-defined protected stack survives bare-composition crowding; quantified interdiffusion suppression

recited halide+buffer+sulfide combination + dR_int endpoint; borohydride bonding-layer stacks distinguished

The primary licensees are halide/sulfide cell makers — companies building high-voltage all-solid-state cells with a halide catholyte and a sulfide separator. For such a program, this is a strategic license because it resolves the principal interface-durability bottleneck intrinsic to that chemistry pairing; a competitor that owns the architecture controls the durability standard for the entire halide-plus-sulfide ASSB cohort. The estimated $5B+ addressable market and the absence of a competing architecture patent make an exclusive or co-exclusive license plausible for a well-positioned cell maker or OEM. A secondary buyer pool is buffer-material and deposition-process suppliers whose products enable the claimed stack — oxide-phosphate or niobate/tantalate materials vendors, ALD or sputter equipment providers working on solid-state battery lines — for whom a field-of-use license tied to the buffer layer is a natural commercial fit. Because the value is architectural and the claim travels with the system rather than with any single material, a serious halide/sulfide cell development program could also justify full acquisition to own the durability standard and prevent competitive licensing to rivals.

The honest risks center on two related gaps. First, Li3InCl6 has a genuine soft phonon mode, which means the bare halide composition is not defensible as a standalone claim; the asset's value is entirely in the protected-stack architecture and endpoint, and an acquirer must accept that frame. This is a known, intentional feature of the claim design — not a surprise — but it does mean the asset cannot be repositioned as a bare-halide composition play if the interface architecture claim were ever challenged. Second, the computational evidence for the ≤25% endpoint is currently modeled, not measured. The MACE molecular-dynamics simulation used short trajectories and small interface cells, so the approximately 18% Cl-S separation figure and the durability endpoint projection are predictive, not experimentally confirmed. The primary de-risking step is fabricating the coupon and running the 500-hour cycling test against an unbuffered control with EDS cross-section verification — this converts the simulation prediction into experimental evidence and directly supports both the claim validity and the commercial durability story. A production-grade DFT-AIMD interface study should follow to complete the mechanistic record. Neither step is technically difficult; both are standard battery-lab experiments, and the first should be achievable within a single calendar quarter of funded effort.