A Polyzwitterion-Mediated Polymer Electrolyte with High Oxidative Stability for Lithium-Metal Batteries.

Abstract

To achieve high-performance solid-state lithium-metal batteries (SSLMBs), solid electrolytes with high ionic conductivity, high oxidative stability, and high mechanical strength are necessary. However, balancing these characteristics remains dramatically challenging and is still not well addressed. Herein, a simple yet effective design strategy is presented for the development of high-performance polymer electrolytes (PEs) by exploring the synergistic effect between dynamic H-bonded networks and conductive zwitterionic nanochannels. Multiple weak intermolecular interactions along with ample nanochannels lead to high oxidative stability (over 5V), improved mechanical properties (strain of 1320%), and fast ion transport (ionic conductivity of 10-4 S cm-1 ) of PEs. The amphoteric ionic functional units also effectively regulate the lithium ion distribution and confine the anion transport to achieve uniform lithium ion deposition. As a result, the assembled SSLMBs exhibit excellent capacity retention and long-term cycle stability (average Coulombic efficiency: 99.5%, >1000 cycles with LiFePO4 cathode; initial capacity: 202 mAh g-1 , average Coulombic efficiency: 96%, >230 cycles with LiNi0.8 Co0.1 Mn0.1 O2 cathode). It is exciting to note that the corresponding flexible cellscan be cycled stably and can withstand severe deformation. The resulting polyzwitterion-mediated PE therefore offers great promise for the next-generation safe and high-energy-density flexible energy storage devices.