Multi-component fluorinated electrolyte additive blend for LiF-rich SEI formation in lithium-metal batteries

This asset protects a multi-component fluorinated electrolyte additive platform designed to engineer a lithium fluoride-rich solid electrolyte interphase (SEI) on lithium-metal anodes. The core insight is that a single-additive approach — the industry's current norm, dominated by fluoroethylene carbonate (FEC) — produces an SEI that is chemically heterogeneous, mechanically weak at high current densities, and insufficient to prevent the filamentary lithium growth that kills cycle life and creates thermal-runaway risk. By combining at least one fluorophosphate source (such as LiPO2F2 or tris(trimethylsilyl) phosphate analogs in the TFEP family), at least one fluoroborate or fluorosulfonate source (LiDFOB, LiBF4, LiBOB, LiFSI, or LiTFSI), the formulation drives the LiF fraction of total-fluorine XPS signal at the cycled anode surface to a target ratio of 0.5 or above. That ratio is the operating specification: it distinguishes a genuinely LiF-dominant SEI from a mixed or fluoropolymer-dominant one, and the two perform very differently under fast-charge, high-current-density cycling. The timing argument is structural. Lithium-metal batteries with energy densities above 400 Wh kg⁻¹ are in active pre-production qualification at multiple cell makers globally, driven by EV range targets and grid-storage cost pressure. The competitive landscape is reaching the point where the electrode chemistry is largely settled and the bottleneck has migrated to electrolyte formulation — specifically the SEI quality problem. Any cell maker entering volume production of lithium-metal or high-silicon-loading cells must solve this problem, and a protected multi-component additive blend with a defined performance threshold is precisely the kind of formulation-level asset that gets licensed rather than independently reinvented. The "critical-mineral recovery and recycling separations" portfolio adds further context: cleaner, longer-lived cells reduce material throughput requirements in the recycling chain, making this asset synergistic with the broader portfolio thesis. The negative-limitation structure of the claims is strategically important. The specification explicitly excludes LiBF4 used alone (a well-known, off-patent single additive), and excludes LiPF6-based electrolytes without the co-additive combination. This is not an oversight but a deliberate freedom-to-operate carve-out that narrows the claim to the genuinely novel multi-arm combination, separating it from prior art while maintaining broad coverage over the useful formulation space. A licensee or acquirer benefits from that clarity: the scope is assertable, not buried under obviousness exposure from single-additive art.

The formulation is organized around three chemical "arms," each contributing a distinct fluorine-delivery mechanism to the forming SEI. The fluorophosphate arm (LiPO2F2, TFEP) preferentially decomposes reductively at the lithium-metal surface to deposit LiF and lithium phosphate species. These phosphate species are known to contribute mechanical integrity and lithium-ion conductivity to the SEI, but the primary function here is fluorine donation. The fluoroborate arm (LiDFOB, LiBOB, LiBF4) adds boron-containing reduction products that can scavenge HF and water-derived impurities while also contributing LiF. The fluorosulfonate arm (LiFSI, LiTFSI) is an established high-ionic-conductivity salt component and a well-characterized LiF precursor; its inclusion in the combination allows the SEI to simultaneously serve the electrolyte bulk conductivity function and the interphase chemistry function. The critical claim is that the combination, when properly proportioned, achieves a LiF-to-total-fluorine XPS ratio of 0.5 or greater at the cycled anode — a threshold that correlates with suppressed dendrite nucleation and reduced "dead lithium" accumulation at high current densities (above 3 mA cm⁻²). The computational work supporting this asset is a mix of atomistic simulation and property prediction rather than the crystal-stability screening that applies to solid-state inorganic candidates. Ab initio molecular dynamics (AIMD) at the lithium-metal interface has been used to predict the decomposition products and nascent SEI chemistry for each arm of the additive blend. Specifically, Simulation Example 18 in the underlying technical record uses per-arm AIMD to predict the LiF content contributed by the fluorophosphate, fluoroborate, and fluorosulfonate components independently, providing a theoretical basis for the ≥0.5 ratio target before experimental confirmation. This is a meaningful computational commitment: AIMD at a realistic electrode-electrolyte interface is expensive (typically tens to hundreds of picoseconds on DFT-grade potential energy surfaces), and it gives a mechanistic explanation for why the combination outperforms any single arm used alone. Because this is a molecular additive system rather than a crystalline inorganic, the standard multi-MLIP phonon consensus workflow (MACE, CHGNet, MatterSim, ORB) does not apply; dynamic stability screening is not the relevant validation modality here. The target SEI ratio of LiF/total-F ≥ 0.5 is grounded in the broader experimental literature on lithium-metal electrolytes. XPS depth profiling of cycled lithium-metal anodes has repeatedly shown that cells with LiF-dominant SEIs outperform fluoropolymer- or lithium carbonate-dominant ones in Coulombic efficiency, impedance stability, and dendrite suppression. The ≥0.5 threshold thus has external experimental support beyond the AIMD predictions, even if the specific multi-arm combination has not yet been fully validated in cycling cells. The critical current density — the current at which dendrite nucleation transitions from suppressed to uncontrolled — is the key performance metric that experimental validation must pin down; the computational work predicts an improvement but does not yet quantify the absolute value. From a materials-design standpoint, the selection of these specific arms is not arbitrary. LiPO2F2 is already used in commercial lithium-ion electrolytes for its passivation effect on aluminum current collectors, so its safety and processability profile is well-characterized. LiDFOB is commercially available and has been studied for its film-forming properties on both cathode and anode. LiFSI and LiTFSI are high-conductivity salts with established supply chains. This means the multi-component formulation sits within the existing electrolyte ingredient ecosystem — it does not require exotic synthesis or new precursor chemistries, which materially de-risks the path from formulation concept to cell qualification.

The addressable market for electrolyte additives and formulations targeting lithium-metal and high-silicon-loading anodes is estimated in the range of $1–3 billion annually at commercial scale, recognizing that this is an early and evolving segment. The estimate reflects the aggregate value-add of specialized additive packages at the electrolyte formulation level: blended electrolyte pricing commands a significant premium over commodity carbonate solvents, and additive packages in advanced cells can represent 5–15% of total electrolyte cost while being responsible for the majority of cell-lifetime differentiation. These estimates are projections contingent on the broader adoption of lithium-metal cells, which is currently in the late development-to-early-production phase. The buyers in this market are cell manufacturers and electrolyte formulators. The cell-maker segment is consolidating around a small number of large-scale producers (in the United States, Korea, Japan, and China) who are all running parallel lithium-metal cell programs for EV and consumer electronics applications. These companies face a common formulation problem and are active licensors of electrolyte IP; precedent licensing deals in the advanced electrolyte space have included both royalty structures (typically 1–3% of electrolyte sales or cell sales attributable to the formulation) and up-front technology access fees. Electrolyte specialty chemical suppliers — companies that formulate and sell ready-mixed electrolytes to cell makers — represent a second buyer class; they acquire additive IP to differentiate their product offerings and capture margin in a market where commodity solvents are increasingly price-competed. The licensing logic follows a standard formulation-IP pattern: the claim covers the additive combination in use (composition plus device-use), meaning it attaches at the point where the formulation is incorporated into a cell. Royalties can be structured against electrolyte volume, cell production volume, or a per-Ah basis. Given the volume of lithium-metal cell production anticipated by the late 2020s across EV and stationary-storage applications, even a modest per-cell royalty on a widely adopted formulation would generate material revenue. The asset is also potentially relevant to silicon-anode cells in conventional lithium-ion chemistries, where the same SEI quality problem exists at lower severity — expanding the total addressable population of cells into which this formulation could be incorporated.

LiF-rich SEI enabling higher cycle life at high current density

>=1 F-P-O + >=1 F-B-O/F-S-O combination targeting LiF-rich SEI; LiBF4-alone excluded

The most natural acquirers or licensees are electrolyte specialty chemical companies and lithium-metal cell manufacturers at late-development stage. In the specialty chemical segment, companies supplying advanced electrolyte packages to tier-one cell makers are actively acquiring additive IP to differentiate commodity-adjacent products; a licensed multi-arm fluorinated additive combination with documented AIMD support and a clear XPS performance threshold gives a formulators' R&D team a validated starting point rather than a blank-slate discovery program. In the cell-maker segment, companies running lithium-metal cell programs for automotive or consumer electronics applications face a common SEI engineering bottleneck and have demonstrated willingness to license electrolyte formulation IP, particularly when the license comes with simulation data that narrows the experimental search space. A secondary buyer class is materials-IP holding companies and battery-technology licensing entities that acquire formulation patents for assertion or cross-licensing in the electrolyte additive space. Given the density of the FTO landscape, cross-licensing value — where this asset is used to negotiate access to complementary single-additive or LHCE formulation patents — may be as commercially significant as direct royalty income from cell production. The asset also has relevance to the silicon-anode lithium-ion cell market (not only lithium-metal), which broadens the potential licensee base to include the larger established lithium-ion cell industry where silicon loading is increasing and SEI quality on silicon is an equally pressing problem.

The primary technical risk is the gap between AIMD prediction and cycling validation. AIMD simulations at the lithium-metal interface are mechanistically informative but operate on timescales (tens to hundreds of picoseconds) and length scales (nanometers) that do not capture the full complexity of an SEI evolving over hundreds of charge-discharge cycles. The predicted LiF/total-F ratio may not be achieved under practical cycling conditions, or may be achieved only at narrow current-density windows. Until XPS data on cycled anodes is in hand, the ≥0.5 threshold remains a design target, not a demonstrated outcome. The critical current density metric — the ultimate functional proof point — is even further from validation. These are normal early-stage risks for a computationally derived formulation concept, and they are the same risks facing virtually every competitor in this space, but they are real. The FTO landscape is the second material risk. The electrolyte additive patent space is dense, and the "narrow" FTO characterization means that working the formulation in a commercial cell requires diligence that the co-additive combination does not inadvertently infringe binary-combination claims already in force from major cell makers or chemical suppliers. The carve-outs built into the claim reduce but do not eliminate this exposure. The roadmap to de-risking both dimensions is straightforward in principle: a cell-level validation campaign generating XPS and critical-current-density data closes the technical gates, and a thorough freedom-to-operate search at the point of commercialization (rather than at the patenting stage) confirms the path to a clean license. The computational head-start shortens the experimental phase but does not substitute for it.