Solid-State Electrolytes in EV Battery Design
Solid-state electrolytes represent a critical advancement in battery technology, offering ionic conductivities approaching 10⁻³ S/cm at room temperature while eliminating the safety risks inherent to liquid electrolytes. Current implementations face challenges with interfacial resistance, mechanical stress during cycling, and maintaining consistent ion transport across grain boundaries.
The fundamental challenge lies in developing materials that combine high ionic conductivity with the mechanical properties needed to maintain stable interfaces during repeated charge-discharge cycles.
This page brings together solutions from recent research—including composite polymer-ceramic architectures, protective interface layers for dendrite suppression, reinforced polymer matrices, and novel manufacturing approaches for reduced interfacial resistance. These and other approaches focus on practical implementations that can scale to commercial battery production while maintaining the safety advantages of solid-state systems.
1. All-Solid-State Battery with Porous Fibrous Carbon Coating Layer for Ionic and Electronic Conductivity
KIA CORP, 2025
An all-solid-state battery with improved charge/discharge efficiency and lifespan compared to conventional solid-state batteries. The battery uses a coating layer made of a porous network of intertwined fibrous carbon that is coated with an inorganic electrolyte. This coating layer is sandwiched between the anode current collector and the solid electrolyte. The coating provides balanced ionic and electronic conductivity, eliminating the need for a separate anode active material. The coated porous carbon network allows lithium intercalation/deintercalation without internal short circuits, improving cycling stability.
2. Solid Electrolyte with Li6-xR1-y-aAy-bMx(BO3)3 Oxide Structure for Low-Temperature Sintering
CANON KABUSHIKI KAISHA, 2025
High-ionic-conductivity solid electrolyte for lithium-ion batteries that can be produced by sintering at low temperatures. The solid electrolyte contains an oxide with the general formula Li6-xR1-y-aAy-bMx(BO3)3, where R is a rare earth element, A is an alkali or transition metal, M is a tetravalent element, and x, y, a, and b are real numbers. The electrolyte exhibits specific X-ray diffraction peaks with a certain angular separation. This composition and structure allows high ionic conductivity when sintered at low temperatures compared to traditional sulfide-based electrolytes.
3. Solid-State Battery Anode-Electrolyte Interface with Chemically Induced Interphase Layer
GOVERNMENT OF THE UNITED STATES AS REPRESENTED BY THE SECRETARY OF THE AIR FORCE, 2025
Improving electrical contact between the anode and solid-state electrolyte in all-solid-state batteries using a chemical connection process. The process involves adding a small amount of a chemical compound to the solid-state electrolyte surface before adding the anode. This forms a specialized solid electrolyte interphase layer that enables better electrical connection between the anode and electrolyte compared to unmodified electrolytes. The chemical connection process allows using phthalocyanine solid-state electrolytes, which are not ductile and cannot flow under high pressure like some other electrolytes, in solid-state batteries.
4. All-Solid-State Lithium Ion Battery with Solid Electrolyte and Thin Cathode Current Collector
TOYOTA JIDOSHA KABUSHIKI KAISHA, 2025
All-solid-state lithium ion battery with reduced risk of short circuits. The battery uses an all-solid-state design with a solid electrolyte between the cathode and anode. The anode reaction is deposition-dissolution of metallic lithium. The battery has a cathode current collector made of materials like SUS, aluminum, nickel, or carbon. This reduces the risk of short circuits compared to using a metal anode current collector. The thinner cathode current collector (1 µm to 500 µm) also helps mitigate short circuits.
5. High-Purity Sulfide Solid Electrolyte with Li6PS4.xOyClzBr1-x-y Composition and Direct Synthesis Method
NINGBO INSTITUTE OF MATERIALS TECHNOLOGY AND ENGINEERING CHINESE ACADEMY OF SCIENCES, 2025
A high-purity sulfide solid electrolyte for all-solid-state batteries that has improved room temperature ionic conductivity and stability compared to existing sulfide electrolytes. The electrolyte has a molecular formula Li6PS4.xOyClzBr1-x-y (0.2 ≤ x,y ≤ 0.6). It is prepared by reacting lithium sulfide precursor with an oxidant to form the electrolyte directly, rather than through ball milling and heat treatment. This avoids impurity phases and allows rapid synthesis with higher initial room temperature conductivity. The direct reaction also provides better stability against lithium electrodes compared to conventional sulfide electrolytes.
6. Sulfide Solid Electrolyte with Li6+x Mx Sb1-x S5 I Composition and Over-Halogenation for Enhanced Lithium Diffusion
MERCEDES-BENZ GROUP AG, 2025
Sulfide solid electrolyte for solid-state batteries with improved power density and manageability compared to existing sulfide electrolytes. The electrolyte has a composition with the fundamental molecular formula Li6+x Mx Sb1-x S5 I, where x is 0.1-0.7 and M is a (semi-)metal like Si, Ge, or Sn. The electrolyte can further be over-halogenated by having more than one halogen like Br and Cl with a common stoichiometry greater than 1. This over-halogenation expands the crystal structure and reduces the activation energy for lithium diffusion to below 0.2 eV.
7. Method for Manufacturing Solid-State Batteries with Layered Deposition of Solid Electrolyte Precursors and Solid Interphase Formation
GM GLOBAL TECHNOLOGY OPERATIONS LLC, 2025
Manufacturing of solid-state batteries through a novel approach that enables the formation of high-performance solid electrolytes for lithium-ion batteries. The manufacturing process involves depositing a positive electrode layer on a substrate, followed by the deposition of a solid electrolyte precursor over the positive electrode layer. This combined deposition approach enables the formation of solid electrolytes with improved uniformity and crack-free surfaces, which are critical for preventing lithium dendrite formation during battery operation. The process also includes applying a liquid electrolyte solution to the positive electrode layer during deposition to create a solid interphase layer, which enhances the structural integrity of the solid electrolyte. The composite structure is then compacted and heat-treated to achieve sintered solid electrolyte properties.
8. Composite Solid Electrolyte Comprising Lithium Lanthanum Zirconium Oxide Nanoparticles with Lithium Phosphate Coating in Fluorine-Containing Colloid
HON HAI PRECISION INDUSTRY CO LTD, 2025
Composite solid electrolyte for batteries that has high ion conductivity, mechanical strength, stability, and cycle life compared to conventional solid electrolytes. The composite electrolyte consists of lithium lanthanum zirconium oxide nanoparticles with a protective layer of lithium phosphate covering the surface. The nanoparticles are dispersed in a fluorine-containing colloid like PVDF. This composite electrolyte improves performance compared to just the nanoparticles alone. The protective layer prevents nanoparticle agglomeration and improves ionic conductivity. The fluorine-containing colloid disperses the nanoparticles and reduces electrical resistance.
9. Method for Densifying Sulfide-Based Solid Electrolytes Using Hydrophobic Thiol Surface Coating
THE REGENTS OF THE UNIVERSITY OF CALIFORNIA, LG ENERGY SOLUTION LTD, 2025
A method for densifying sulfide-based solid electrolyte materials through the application of an organic coating. The method involves forming a sulfide-based solid electrolyte material with a surface coating containing a hydrophobic thiol compound, followed by densification through cold pressing. The coating protects the electrolyte during pressing while enhancing its mechanical properties and interface conductivity. The resulting densified solid electrolyte pellets can be used in all-solid-state batteries, particularly in secondary cells like lithium-ion batteries, offering improved safety, performance, and energy density compared to conventional liquid-based systems.
10. High Dielectric Polymer Electrolytes with Branched Polymer Functionalization for Lithium-Ion Batteries
IONIC MATERIALS INC, 2025
High dielectric polymer electrolytes for lithium-ion batteries that enable high conductivity and safety compared to conventional liquid electrolytes. The polymer electrolytes have a dielectric permittivity >10 and glass transition temperature <-30°C. They are made by functionalizing branched polymers containing multiple reactive nucleophilic sites. The functionalization increases dielectricity while lowering Tg. The resulting high dielectric polymers have improved ion solubility and conductivity in electrolytes. Using them in lithium-ion batteries provides better performance and safety compared to liquid electrolytes.
11. Cross-Linked Polymer Network Electrolyte with Dispersed Polar Compound and Integrated Ceramic Compounds
LG ENERGY SOLUTION LTD, 2025
A solid electrolyte with improved ionic conductivity for all-solid-state batteries. The electrolyte is a cross-linked polymer network containing a polar compound dispersed in the network. The polar compound is added in gaseous form and absorbed into the polymer. The cross-linking agent connects the polymer chains to form a network structure. This improves mechanical strength while allowing polar compound dispersion. The cross-linked polymer network with absorbed polar compound provides enhanced ionic conductivity compared to unmodified polymers. The electrolyte also includes ceramic compounds and optionally lithium salt.
12. Thin Film Solid State Electrolytes Comprising Lithium-Stuffed Garnet Oxides with Variable Surface Layers and Specific Bulk Composition
QUANTUMSCAPE BATERRY INC, 2025
Thin film solid state electrolytes for lithium-ion batteries with low impedance, reduced tendency for lithium dendrite formation, and stable cycling performance. The electrolytes are lithium-stuffed garnet oxides with specific chemical compositions and surface treatments. The electrolyte thickness is 10-100 microns, with top/bottom surface areas 10x larger. The electrolyte bulk has the composition LixLa3Zr2O12(Al2O3) with 3 <= x <= 8 and 0 <= y <= 1. The surfaces have less than 1 micron of carbonate, hydroxide, oxide, or peroxide layers. The electrolytes are made by calcining, sintering, and annealing the garnet precursors in reducing atmospheres at elevated temperatures. The
13. Synthesis Method for Sulfide-Based Solid Electrolytes via Metathesis Reaction in Solution
SOLID POWER OPERATING INC, 2025
Low-cost synthesis method for sulfide-based solid-state electrolytes for lithium batteries. The method involves dissolving a phosphorous compound and an alkali metal salt like sodium sulfide in solvents, then mixing with a second alkali metal salt like lithium chloride. The metathesis reaction between the two alkali metals produces the solid electrolyte. The solvents are removed to isolate the electrolyte. This avoids expensive precursors and ball milling compared to existing methods.
14. Solid-State Battery with Domed Notches and Protrusions Forming 3D Interconnected Electrode-Electrolyte Structure
FORD GLOBAL TECHNOLOGIES LLC, 2025
Battery design for solid-state batteries with improved charging speed and stability. The design involves using a specific pattern of domed notches on the cathode and anode plates, with corresponding protrusions in the solid electrolyte that fit into the notches. This creates a 3D interconnected structure between the electrodes and electrolyte that reduces Li ion diffusion pathlengths compared to flat interfaces. It allows faster charging without issues like Li plating due to more uniform current density distribution and mechanical stability of the interconnected structure.
15. Composite Metal Foil with Nickel and Zinc Layers for Controlled Lithium Deposition in Solid-State Electrolytes
INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE, 2025
Composite metal foil for lithium batteries with enhanced current collection properties, particularly for sulfur-based solid-state electrolyte systems. The foil comprises a conductive substrate, a nickel layer, and a zinc layer. The nickel layer is positioned in direct contact with the substrate, while the zinc layer is strategically positioned at the surface of the nickel layer. The zinc layer has a lower nucleation overpotential than the nickel layer, enabling controlled deposition of lithium at the current collector interface. This configuration addresses the challenges of sulfur-based electrolytes, particularly in systems without negative electrodes, by providing a controlled current collection mechanism.
16. Automated Solid-State Battery Manufacturing with Sequential Layer Deposition in Sealed Chambers
SEMICONDUCTOR ENERGY LABORATORY CO LTD, 2025
Fully automated manufacturing process for solid-state batteries that avoids exposure to air to improve yield and cycle life. The process involves sequentially depositing the battery layers in a sealed chamber setup. It starts with forming a conductive layer on an insulating substrate, followed by the negative electrode active material, solid electrolyte, positive electrode active material, and final conductive layer. The solid electrolyte is co-evaporated using an organic lithium-silicon complex. The layers are transferred between chambers without air exposure. This prevents contamination and improves cycling performance by avoiding oxygen or moisture ingress.
17. Sulfide-Based Solid-State Electrolyte with Group 13/14 Elements and Variable Phase Composition
SOLID POWER OPERATING INC, 2025
Solid-state lithium battery electrolyte material with high ionic conductivity and compatibility with high voltage cathodes and lithium metal anodes. The electrolyte is a sulfide-based material with a composition of Li, T, X, and A where T is a Group 13 or 14 element, X is a halogen or BH4, and A is S, Se, or N. The material can have glass ceramic and crystalline phases with specific X-ray diffraction peaks. The electrolyte synthesis involves milling and heating precursor compositions to create the final sulfide glass, which can then crystallize into the desired phases.
18. All-Solid-State Lithium Ion Battery Anode with Lithium-Amorphous Carbon Composite Layer and Low Sheet Resistance
SAMSUNG SDI CO LTD, 2025
All-solid-state lithium ion battery with improved cycle life and reduced dendrite growth for higher capacity and safety. The battery uses an optimized composition and structure for the anode active material layer. The anode layer contains lithium as the active material mixed with amorphous carbon in a weight ratio of 1:3 to 1:1. This ratio enhances adhesion between the lithium and carbon to prevent lithium dendrites from growing through the solid electrolyte. The anode also has a low sheet resistance below 0.5 milliohms-centimeters to further suppress dendrite formation.
19. Composite Solid Electrolyte with Vapor-Deposited Polar Compound in Cross-Linked PEO Copolymer Network
LG ENERGY SOLUTION LTD, 2025
A composite solid electrolyte for all-solid-state lithium batteries that improves ionic conductivity without damaging the polymer matrix. The composite electrolyte is made by vapor depositing a polar compound into the solid electrolyte containing a cross-linked polymer network formed from a PEO copolymer with functional groups. The polar compound enhances ion mobility by relaxing the polymer chains and dispersing ceramic particles. The cross-linking functional groups form a network structure to prevent polymer deformation. This improves mechanical properties while allowing uniform polar compound deposition. The composite electrolyte shows higher ionic conductivity than conventional solid electrolytes.
20. Laminated Cell Structure with Inert Gas-Filled Depressurized Layer for Sulfide Solid Electrolyte Containment
TOYOTA JIDOSHA KABUSHIKI KAISHA, 2025
Laminated cell design for solid state batteries with sulfide solid electrolytes that reduces leakage of high-temperature hydrogen sulfide gas from inside the cell. The cell has a laminated structure with an electrode stack containing a sulfide solid electrolyte. The space between the laminated film and the exterior material is depressurized and filled with an inert gas to prevent hydrogen sulfide gas generated during charging from escaping and potentially damaging the cell seals.
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