Grain-Boundary-Rich Interphases for Rechargeable Batteries

The formation of stable interphases on the electrodes is crucial for rechargeable lithium (Li) batteries. However, next-generation high-energy batteries face challenges in controlling interphase formation due to the high reactivity and structural changes of electrodes, leading to reduced stability and slow ion transport, which accelerate battery degradation. Here, we report an approach to address these issues by introducing multicomponent grain-boundary-rich interphase that boosts the rapid transport of ions and enhances passivation toward prolonged lifespan. This is guided by fundamental principles of solid-state ionics and geological crystallization differentiation theory, achieved through improved solvation chemistry. Demonstrations showcase how the introduction of the interphase substantially impacts the Li-ion transport across the interphase and the electrode–electrolyte compatibility in cost-effective electrolyte solutions optimized with multiple Li salts. The resulting interphases feature microstructures rich in inorganic grain boundaries with a diverse array of nanosized grains, presenting enhanced Li-ion transport. Comprehensive analyses revealed that this realizes remarkable electrochemical stability over extended cycling periods by inhibiting electrode corrosion, thus holding promise for high-capacity thin-Li-metal, Si-based anodes, and even Li-free anodes when paired with high-capacity oxide cathodes. This work opens new avenues to customize protective interphases on high-capacity electrodes, promoting the development of batteries with the highest energy density using cost-effective electrolytes.