Fueling from the Electrochemistry of Halide Solid Electrolytes

Unveiling the electrochemistry of solid-state Li2ZrCl6 halide electrolyte, we reveal its dual function as both an ion conductor and a supplementary electron source/sink. This groundbreaking discovery leads to a remarkable long-term enhancement of the specific capacity of industry-relevant heavily loaded LiFePO4 electrodes by several tens of percent, while significantly amplifying that of Si-based or anode-less full cells through effective compensation for side reactions. We show that these effects can potentially be tuned by adjusting the initial xLiCl-ZrCl4 composition of the solid electrolyte, which may thus become a new and mighty parameter for balancing the two electrodes.