Sponge-Like Porous-Conductive Polymer Coating for Ultrastable Silicon Anodes in Lithium-Ion Batteries

Urgent calls for reversible cycling performance of silicon (Si) requires an efficient solution to maintain the silicon-electrolyte interface stable. Herein, a conductive biphenyl-polyoxadiazole (bPOD) layer is coated on Si particles to enhance the electrochemical process and prolong the cells lifespan. The conformal bPOD coatings are mixed ionicelectronic conductors, which not only inhibit the infinite growth of solid electrolyte interphase (SEI) but also endow electrodes with outstanding ion/electrons transport capacity. The superior 3D porous structure in the continuous phase allows the bPOD layers to act like a sponge to buffer volume variation, resulting in high structural stability. The in situ polymerized bPOD coating and it-driven thin LiF-rich SEI layer remarkably improve the lithium storage performance of Si anodes, showing a high reversible specific capacity of 1600 mAh g^-1 even after 500 cycles at 1 A g^-1 along with excellent rate capacity of over 1500 mAh g^-1 at 3 A g^-1 . It should be noticed that a long cycle life of 800 cycles with 1065 mAh g^-1 at 3 A g^-1 can also be achieved with a capacity retention of more than 80%. Therefore,  we  believe this unique polymer coating design paves the way for the widespread adoption of next-generation lithium-ion batteries.