Today's lithium-ion batteries use a liquid electrolyte that is flammable and limits how aggressively cells can be designed. A solid-state battery (SSB) swaps it for a solid electrolyte that conducts lithium ions. This enables a pure lithium-metal anode — far higher capacity — and removes the fire-prone liquid, the two biggest prizes in battery research.
Working principle
The solid electrolyte must conduct Li⁺ ions quickly while blocking electrons and mechanically suppressing dendrites (lithium needles that short-circuit cells). Three material families compete: oxides (e.g. garnet LLZO — stable but brittle), sulphides (very high conductivity, soft, but air-sensitive), and polymers (flexible but lower conductivity at room temperature). Ions hop between sites in the solid lattice between the electrodes.
| Family | Conductivity | Pro | Con |
|---|---|---|---|
| Oxide (garnet) | Moderate | Stable, safe | Brittle, interface |
| Sulphide | High | Ductile, fast Li⁺ | Air-sensitive |
| Polymer | Lower (RT) | Flexible, processable | Needs heating |
Key challengeThe make-or-break issue is the solid–solid interface: maintaining intimate contact during cycling, controlling resistance, and stopping dendrites are the dominant obstacles to commercialisation.
Applications
- Higher-range, faster-charging electric-vehicle batteries
- Safer consumer electronics and wearables
- Aviation and grid storage where energy density matters
References & further reading
- Janek & Zeier, “A solid future for battery development,” Nature Energy, 2016.
- Manthiram et al., “Lithium battery chemistries enabled by solid-state electrolytes,” Nature Reviews Materials, 2017.
- Famprikis et al., “Fundamentals of inorganic solid-state electrolytes,” Nature Materials, 2019.