Energy-storage and self-healing microcapsules for secondary batteries: from preparation methods and electrochemical performance to enhancement mechanisms.

With the growing demand for high energy-density, long cycle-life and high safety secondary batteries, conventional electrode and interface materials are facing severe challenges in terms of structural stability, reversibility and reliability. Microcapsules provide a potential approach to alleviate several concerns via confinement encapsulation, interface isolation, sustained-release regulation and stress buffering. Here, we systematically introduce typical microcapsules and their conceptual structures such as core-shell spheres used in lithium-ion batteries, lithium-sulfur batteries, magnesium-ion batteries, magnesium/lithium hybrid-ion batteries, sodium-ion batteries, etc., which exhibit good self-healing and energy-storage performances. The preparation methods, performances and improvement mechanisms reported by our group and some other teams have been summarized in this review. The future research directions are also indicated, which are significant for the development of high-performance microcapsules for battery systems.