A Robust Li+-Rich Protective Layer for High-Performance Dendrite-Free Li Metal Batteries

Essentially, rapid Li + accumulation in the anode region triggers a strong space charge layer and significant Li + concentration gradient, which ultimately leads to Li dendrites and interface issues. Herein, a mechanically robust layer consisting of lithiated-palygorskite (Li-Pal) and thermoplastic polyurethane elastomer (TPU) is employed to regulate the Li electrochemistry. The negatively charged Li-Pal surface demonstrates an exceptional lithiopholicity, which can leverage Li + supplement function to mitigate the concentration gradient. Meanwhile, the high elasticity of TPU can suppress Li dendrite growth and penetration during cycling. Enabled by such a hybrid layer, a high Coulombic efficiency (CE) of 99.1% over 300 cycles is delivered in Li/Cu half cells, and a long cycling life over 1400 h is achieved in a symmetric cell. The corresponding LiFePO 4 full cells present a high capacity retention of 90.6% over 1000 cycles at 5 C. This interfacial engineering highlights the synergetic design of a protective layer with high mechanical stability and Li + affinity for dendrite-free Li metal batteries.