Highly stable 3D Li metal anodes enabled by a shielding/rectifying polymer layer

The practical application of Li metal anode is hindered by the uncontrollable dendrites growth, severe side reactions and huge volume fluctuation, which would result in low Coulombic efficiency (CE) and poor cycling performance. Herein, a 3D Li host is functionalized by a low-cost and environment-friendly polyvinyl alcohol (PVA) layer via a facile solution immersion method to solve the above issues. The polymer layer can act as a stable artificial SEI with high ionic conductivity during cycling, so as to isolate the direct contact between Li metal and electrolyte and then avoid interfacial side reaction. In addition, the abundant hydroxyl (-OH) polar groups in PVA, which own a strong binding energy with Li atoms, can effectively regulate Li plating/stripping behaviors on the 3D framework. As a result, the symmetric cell using PVA-Cu mesh-Li electrode delivers a superior long-term stability over 1000 h with a low average voltage hysteresis of 17 mV at 1 mA cm-2. And the PVA-Cu mesh-Li || LiFePO4 full cell can remain a high discharge capacity of 104.4 mAh g-1 and a high CE of 99.1% after 350 cycles at 5 C.

Automated summary

A 3D Li host functionalized by a polyvinyl alcohol (PVA) layer is used to address the issues of dendrites growth, side reactions and volume fluctuation in Li metal anodes. The PVA layer acts as a stable artificial solid-electrolyte interface (SEI) with high ionic conductivity, preventing direct contact between Li metal and electrolyte. Moreover, the hydroxyl (-OH) groups in PVA effectively regulate Li plating/stripping behavior. The results show superior long-term stability and high Coulombic efficiency in the symmetric cell and full cell configurations.