Optimizing Organic Electrode Microstructures for All-Solid-State Batteries Through Hardness Manipulation

All-solid-state batteries are regarded as one of the future energy storage technologies capable of competing with the state-of-the-art Li-ion batteries. Despite tremendous progress, the performance of all-solid-state metal batteries remains unsatisfactory. Organic electrode materials have recently emerged as a strong contender to inorganic materials for solid-state batteries. A key benefit of organic electrode materials is their inherent softness, which promotes intimate contact with solid electrolytes during battery operation and therefore improving longevity. However, this softness can be a double-edged sword. Under compaction, soft organic active materials tend to deform to envelop the harder solid electrolyte particles, impeding ion transport. This mismatch in hardness limits active material utilization at high fraction, resulting lower cell-level energy density. Here we report the formation of favourable microstructures in organic electrodes by judiciously “softening” solid electrolytes and simultaneously “hardening” organic materials. We show how soft organic redox materials could enable intimate interfacial contact with solid electrolytes under low operating pressure. This strategy of hardness manipulation provides a universal way for creating favorable electrode microstructures in solid-state electrodes involving soft active materials to ensure efficient ion transport.