A Sponge-Driven Elastic Interface for Lithium Metal Anodes

The lithium (Li) metal is one promising anode for next generation high-energy-density batteries, but the large stress fluctuation and the nonuniform Li deposition upon cycling result in a highly unstable interface of the Li anode. Herein, a simple yet facile engineering of the elastic interface on the Li metal anodes is designed by inserting a melamine sponge between Li and the separator. Driven by the good elasticity of the sponge, the modified Li anode maintains a Coulombic efficiency of 98.8% for 60 cycles and is cyclable at 10 mA cm^-2 for 250 cycles, both with a high capacity of 10 mA h cm^-2. We demonstrate that the sponge can be used to replace the conventional polypropylene as a porous yet elastic separator, showing superior cycling and rate performance as well. In addition to the efficiency of the elastic interface on the cycling stability, which is further confirmed by an in situ compression-electrochemistry measurement, the porous structure and polar groups of the sponge demonstrate an ability of regulating the transport of Li ions, leading to a uniform deposition of Li and the suppression of Li dendrites in cycling.