A Self-Healing Lithium–Sulfur Battery Using Gel-Infilled Microcapsules

High-energy-density lithium–sulfur batteries have been considered to be promising next-generation power batteries for electric vehicles (EVs). However, the common crash of batteries in EVs would lead to the formation of electrode cracks and the increase in resistance that causes critical risks of catching fire in the battery system. Herein, we develop a self-healing lithium–sulfur battery by using polymer gel-infilled microcapsules embedded in a sulfur cathode. When the electrode cracks, microcapsules break and release the gel core into the cracks, enabling the re-connection of the pathways for transferring electrons. In our study, a polymer gel precursor is encapsulated in microcapsules through a liquid-driven microfluidic approach, and then the precursor is polymerized to form a gel core inside the microcapsules. The self-healing battery exhibits a stable capacity of 825 mAh g–1 after 200 cycles. More importantly, after manually impacting the cathode with a force before battery assembly and free-falling the battery from a determined height repeatedly, the batteries maintain stable electrochemical performance compared to the ones without microcapsules, exhibiting a self-healing function that is applicable for developing emerging energy storage systems for EVs.