Solid-State Revolution

Traditional lithium-ion batteries use a liquid electrolyte that can leak, degrade, and occasionally catch fire. Solid-state batteries swap that liquid for a solid ceramic or glass electrolyte, removing those risks.

The payoff could be roughly double the energy density — meaning an electric car that travels twice as far on one charge. Toyota, Samsung, and dozens of startups are racing to commercialize it.

Sodium-ion batteries are another contender. Sodium is about 1,000 times more abundant than lithium and far cheaper to source. It stores a little less energy per kilogram, but its low cost makes it ideal for grid-scale storage.