Fast charging forces lithium ions to plate onto the anode faster than they can spread evenly. In a liquid electrolyte those uneven spots grow into needle-like metallic dendrites that push straight through the liquid toward the cathode. Once a dendrite fully bridges the gap it shorts the cell internally — a low-resistance metal path that dumps energy as heat and can cascade into thermal runaway.
A solid electrolyte is a mechanically tough ceramic or polymer layer instead of a liquid. It physically resists dendrite penetration far more effectively, so the same fast-charge stress produces only shallow, blocked growth — and it enables a higher-capacity lithium-metal anode, which is why solid-state cells pack more energy into the same size and weight.
- Charge rate — higher C-rates plate lithium faster and roughen the deposit, accelerating dendrite growth in the liquid cell.
- Run 1 cycle / Auto-cycle — advance charge cycles manually or let both cells cycle continuously.
- Bridging % — how far the fastest-growing dendrite has crossed the gap; 100% means a short circuit.
- Energy-density figures are illustrative, based on published lab/prototype ranges for conventional Li-ion versus early solid-state cells.