The material system of solid-state batteries primarily revolves around solid electrolytes, cathode materials, and anode materials, with significant performance and application scenario differences across various technological approaches. Below is a classification and characteristics of current mainstream material systems:

1. Solid Electrolyte Material System

Sulfide Electrolytes

Characteristics: Highest ionic conductivity (>10 mS/cm), approaching liquid electrolyte levels, but with poor chemical stability, prone to reacting with moisture to produce toxic hydrogen sulfide.

Representative Materials: Lithium sulfide (Li₂S), lithium thiophosphate (Li₃PS₄), etc.

Applications: Primary focus of Japanese and Korean companies (e.g., Toyota, Samsung), requiring production in dry environments.

Oxide Electrolytes

Characteristics: Excellent chemical stability, high voltage tolerance (>5V), but lower room-temperature ionic conductivity (10⁻⁴~10⁻³ S/cm).

Representative Materials: Garnet-type (Li₇La₃Zr₂O₁₂), perovskite-type (LLTO), NASICON-type.

Applications: Key R&D direction for Chinese companies like WeLion and Qingtao Energy.

Polymer Electrolytes

Characteristics: Mature processing, good flexibility, but low room-temperature conductivity (<10⁻⁵ S/cm), requiring heating above 60°C for use.

Representative Materials: Polyethylene oxide (PEO)-based composites.

Applications: Led by European companies (e.g., Bosch), suitable for flexible electronics.

Halide Electrolytes

Characteristics: Combines high ionic conductivity and air stability, but with higher costs.

Representative Materials: Lithium chloride (LiCl) composites, explored by companies like BYD.

2. Cathode Material System

High-Voltage Cathode Materials

Layered Oxides: E.g., high-nickel ternary (NMC811), theoretical capacity 250 mAh/g, but requires solving interfacial side reactions with solid electrolytes.

Spinel Structure: E.g., lithium nickel manganese oxide (LiNi₀.₅Mn₁.₅O₄), voltage up to 4.7V, energy density ~635 Wh/kg, but needs doping stabilization.

Polyanion Type: E.g., lithium iron phosphate (LFP), good thermal stability but poor conductivity, best paired with oxide electrolytes.

Lithium-Rich Manganese-Based Materials

Theoretical capacity >300 mAh/g, but suffers from low initial efficiency and voltage decay, requiring short-term composite use.

3. Anode Material System

Silicon-Based Anode

Capacity reaches 4200 mAh/g through carbon doping to suppress silicon expansion, currently a transitional solution.

Lithium Metal Anode

Theoretical capacity 3860 mAh/g, but requires solving lithium dendrite issues, better suited for sulfide electrolytes.

4. Regional Technological Differences

China: Focuses on oxide electrolytes + high-nickel ternary cathodes;

Japan/Korea: Prioritizes sulfide electrolytes + lithium metal anodes;

Europe: Favors polymer electrolytes + silicon-based anodes.