The selection of cathode materials for solid-state batteries requires comprehensive consideration of factors such as energy density, cycle life, safety, and cost. Current mainstream technical routes and future development directions are as follows:

I. Mainstream cathode material types and characteristics

Lithium metal cathode

Advantages: Theoretical specific capacity up to 3860mAh/g, low electrochemical potential (-3.04V), capable of significantly increasing battery energy density to over 500Wh/kg.

Challenges: Prone to lithium dendrite formation causing short circuits, high interfacial resistance, requiring multilayer protective designs (e.g., Harvard's "three-layer sandwich structure") to optimize stability.

Current status: Contemporary Amperex Technology plans to launch second-generation all-solid-state batteries using lithium metal anodes by 2026.

Silicon-based anode

Advantages: Theoretical capacity of 4200mAh/g (11 times graphite), suitable for high energy density requirements; volume expansion can be mitigated to 30% through nanoization (particles <20nm) and composite structures (e.g., Si@C).

Progress: By 2025, silicon oxide anode (SiOx/C) cycle life will exceed 1000 cycles with capacity retention >85%; Bettery's sixth-generation silicon anode has entered mass production, with Gotion High-Tech's Ningbo base reaching 40,000-ton capacity.

Compatibility: Works synergistically with sulfide solid electrolytes, where external pressure (0.49MPa) suppresses expansion, achieving 99.95% Coulombic efficiency after 500 cycles.

Carbon-based anode (graphite/hard carbon)

Status: Mature technology with low cost, but specific capacity limited to 360mAh/g approaching theoretical limits, still serving as transitional solution in semi-solid-state batteries.

II. Technical route differences and regional distribution

China: Focuses on silicon-carbon anode + oxide electrolytes, targeting over 1 million tons production capacity by 2025.

Japan/Korea: Concentrates on lithium metal anode + sulfide electrolytes, with dendrite resolution as key challenge.

Europe/US: Explores polymer electrolytes paired with silicon anode, emphasizing flexible application scenarios.

III. Future breakthrough directions

Interface engineering: Developing self-healing binders (e.g., PAA system) and LiF-rich electrolyte additives to improve initial efficiency to 90%.

Cost reduction: Using biomass silicon sources (rice husk, bamboo) and scaled equipment to decrease silicon-carbon anode cost from 750,000/ton to below 150,000/ton.

All-solid-state integration: Sulfide-based all-solid-state batteries paired with silicon or lithium metal anodes expected to enter mass production during 2027-2030.