Lithium oxide chloride antiperovskite and magnesium-doped sodium thiophosphate solid electrolytes

The solid electrolyte race for next-generation sodium and lithium solid-state batteries is narrowing rapidly around a handful of material families — thiophosphates, sulfides, halides, and antiperovskites — and the competitive landscape shifted materially in 2025 when a tungsten-substituted Na3PS4 composition entered the prior-art record under 35 U.S.C. §102. That single reference immediately foreclosed the most straightforward W-substituted thiophosphate claims for any new filer. This asset responds directly to that dynamic: it is a strategically constructed carve-out that preserves composition-of-matter coverage over three structurally and chemically distinct electrolyte platforms that the W-Na3PS4 reference does not touch — the Li3OCl antiperovskite, the Na2LiAlF6 double-fluoride perovskite, and the divalent-doped sodium thiophosphate family constrained to magnesium and zinc dopants with calcium and tin explicitly excluded. Understanding why this carve-out has value requires appreciating the broader filing family it supports. The parent family covers solid-electrolyte compositions for both sodium and lithium solid-state batteries as part of the portfolio's integrated packaging, storage, and PFAS-treatment systems program. The antiperovskite arm (Li3OCl) and the fluoride-bridged arm (Na2LiAlF6) serve as independent anchors that remain fully defensible regardless of what happens to the thiophosphate space under future §102 challenges. The divalent-dopant thiophosphate arm — Na(3-2x)MxPS4 with M restricted to Mg or Zn — preserves a non-trivial compositional footprint in a space that incumbents have not yet fully occupied with issued claims, giving a licensee a genuine freedom-to-operate corridor and a hedge against supply-chain or performance limitations of the tungsten-substituted alternatives. This is an honest backup and defensive filing, not a flagship — but its strategic role within the family is real and its timing is deliberate.

The engines did not fully agree here — the asset carries that uncertainty openly rather than overstating confidence.

The three compositions in this asset span two distinct crystal-chemistry families. Li3OCl crystallizes in the cubic antiperovskite structure (space group Pm-3m), where lithium occupies the B-site, oxygen the anion center, and chloride the corner positions — an inverted arrangement relative to the classic ABO3 perovskite. This structure has been studied for lithium-ion conduction since at least 2012, and its key peculiarity is well-established in the literature: harmonic phonon calculations at 0 K routinely produce imaginary modes (soft modes), which reflect the shallow energy landscape that also enables fast Li+ hopping. The material is not dynamically unstable in the operational sense — it is entropically stabilized at room temperature and above, where anharmonic effects and thermal occupation of the soft-mode branch suppress the instability. This distinction between 0 K harmonic softness and finite-temperature dynamic stability is critical context for interpreting the computational results on this composition. MACE, one of the two machine-learning interatomic potentials applied in the computational screen, returns a minimum phonon frequency of -2.93 THz for Li3OCl — a large imaginary mode that, taken in isolation, would flag the structure as unstable. The second potential used in the screen did not produce a result for this structure, and no CHGNet, ORB, or MatterSim results are yet available. This means the multi-potential consensus test that Lattice Graph's pipeline normally requires — where at minimum two independent potentials must agree that a structure shows no imaginary modes — has not been satisfied for Li3OCl. The -2.93 THz MACE result is physically expected for the antiperovskite at 0 K and does not contradict the experimental literature, but it does mean the pipeline's standard consensus gate has not been passed, and this composition currently lacks the multi-MLIP agreement that would make the computational case fully self-standing. A finite-temperature AIMD run or an anharmonic phonon treatment (e.g., self-consistent phonon theory) would be required to close this gate and demonstrate that the mode is indeed suppressed at operating temperature. Na2LiAlF6 is the load-bearing arm of this asset. It belongs to the elpasolite (double perovskite) family with formula A2BB'X6, where A = Na, B = Li, B' = Al, and X = F. Unlike the antiperovskite, this compound produces a fully positive phonon density of states under finite-displacement (FD) calculations, with a minimum frequency of +0.21 THz — confirming zero-Kelvin dynamic stability with no imaginary modes. This is a fluoride-based framework, so it is chemically distinct from both the thiophosphate and the antiperovskite arms, broadening the compositional coverage of the filing family across three different anion chemistries (oxide-chloride, fluoride, and sulfide-phosphide). The ionic conductivity of fluoride double perovskites is generally lower than sulfide thiophosphates at room temperature, but their electrochemical windows are wider and their chemical compatibility with oxide cathodes is superior, positioning Na2LiAlF6 as a different operational niche rather than a direct substitute. The divalent-doped thiophosphate compositions — represented by Na2.6Mg0.2PS4 as the exemplar — operate on a well-understood doping principle: substituting a divalent cation (Mg2+ or Zn2+) for Na+ creates sodium vacancies that enhance ionic conductivity by lowering the migration barrier for Na+ hopping through the tetrahedral PS4 framework. The specific restriction to Mg and Zn, with Ca and Sn explicitly excluded, is not arbitrary: it reflects the freedom-to-operate landscape, carving out a space that is not covered by the 2025 W-Na3PS4 reference and avoids Ca and Sn compositions that carry their own prior-art exposure. Computational validation of the divalent-dopant arm is currently incomplete — ab initio molecular dynamics (AIMD) simulations needed to demonstrate room-temperature stability and extract diffusion coefficients have not been finalized — making this the arm with the most open validation gates.

The addressable market for solid electrolytes in sodium and lithium solid-state batteries is estimated in the range of one to five billion dollars, spanning cell manufacturers, materials suppliers, and automotive and stationary-storage integrators who are actively qualifying solid-electrolyte chemistries. Thiophosphate electrolytes — particularly the Na3PS4 family and its sulfide-glass analogs — are among the leading candidates for sodium solid-state batteries because they combine reasonable room-temperature ionic conductivity with processability in dry-room environments. The antiperovskite family (Li3OCl and its analogs) has attracted sustained interest for lithium applications because of its simple synthesis, earth-abundant constituents, and tolerance for mechanical stress in solid-cell stacks. Buyers in this space include cell makers, tier-one automotive suppliers building solid-state battery R&D programs, and materials companies that supply electrolyte powders or thin films under long-term supply agreements. The royalty and licensing logic for a backup composition patent is somewhat different from a pioneering claim. A licensee here is primarily purchasing freedom to operate and hedge coverage — the ability to pivot to a non-tungsten thiophosphate or an antiperovskite electrolyte chemistry if the dominant W-substituted compositions run into supply-chain constraints, regulatory issues, or invalidation of their own IP. For a battery maker that is already investing hundreds of millions in solid-state cell development, the cost of losing electrolyte IP freedom is enormous relative to the cost of licensing a carve-out position. Licensing value is therefore driven less by the royalty rate on a specific product and more by the strategic optionality the patent family provides. The divalent-dopant arm (Mg/Zn thiophosphate) also has a path to direct product embodiment if a licensee develops a specific Na2.6Mg0.2PS4 or Zn-analog electrolyte for commercial cells, at which point the composition-and-device-use claims would attach directly to manufactured product. The realistic near-term monetization pathway is an assertion license or a package license bundled with other electrolyte IP from the same portfolio.

non-tungsten, non-Ca thiophosphate carve-out + antiperovskite arm

non-tungsten carve-out; divalent dopants restricted to Mg/Zn (Ca/Sn excluded)

The most direct acquirers or licensees for this asset are manufacturers developing sodium solid-state battery cells, particularly those that have chosen thiophosphate electrolyte chemistries as their primary development path and need IP coverage for non-tungsten alternatives as a hedge. This includes Japanese and Korean cell makers with active Na solid-state programs, as well as Western startups building Na-ion solid-state cells for grid storage applications where lithium supply concerns are a driver. For the Li3OCl arm, the natural buyers are lithium solid-state battery developers — the antiperovskite is a lithium-ion conductor, not sodium, and its customer set overlaps with but is not identical to the thiophosphate space. A portfolio acquirer consolidating solid-electrolyte IP across multiple chemistries (thiophosphate, antiperovskite, fluoride, halide) would see this asset as a complementary piece that broadens compositional coverage without overlapping existing holdings. Strategic fit is strongest for a buyer that (a) already holds or is building a license position in the parent electrolyte family, (b) has an active product development program in sodium or lithium solid-state cells, and (c) values optionality against supply-chain or IP disruption in the tungsten-substituted thiophosphate space. The asset is less attractive as a stand-alone acquisition because its value is amplified by the parent family context — the device-use claims are most powerful when combined with broader cell architecture IP. A licensing structure that bundles this carve-out with related electrolyte and cell-design claims from the same portfolio would command meaningfully higher value than this asset alone.

The most significant risk is the incomplete computational validation stack. The multi-MLIP consensus test — Lattice Graph's standard requiring two or more independent potentials to agree on dynamic stability — has not been satisfied for Li3OCl (MACE shows large imaginary modes; the second potential result is absent), and AIMD for the divalent-dopant thiophosphate arm is incomplete. While the Li3OCl instability at 0 K is physically well-understood and the material is experimentally known to be stable at room temperature, a patent prosecution or litigation context requires a defensible computational and experimental record, and the current record has gaps. Additionally, the prior-art landscape for Li3OCl antiperovskite is mature; older publications and any issued patents on antiperovskite electrolytes are a risk to the breadth of those claims specifically. The FTO corridor for the Mg/Zn thiophosphate arm depends on how broadly incumbent Na3PS4 patent holders have claimed divalent-dopant variations in existing applications — a full patent-space search focused on divalent dopants in Na3PS4 is a necessary diligence step before asserting these claims. The roadmap to de-risk is defined: complete AIMD on the Mg/Zn thiophosphate series to establish room-temperature diffusivity; apply at least two additional MLIP potentials (MatterSim and ORB) to Li3OCl to test whether the imaginary mode persists across potentials or is a MACE-specific artifact; run an anharmonic or finite-temperature phonon treatment for Li3OCl to demonstrate thermal stabilization computationally; and generate experimental cycling data for at least one cell using a Na2.6Mg0.2PS4 electrolyte. On the IP side, a targeted freedom-to-operate search across the divalent-dopant thiophosphate sub-space — focused on Mg and Zn substitution specifically — should be completed before the asset is licensed or asserted.