Chloride-Reinforced Solid Polymer Electrolyte for High-Performance Lithium Metal Batteries

Flexible solid-state polymer electrolytes (SPEs) enable intimate contact with the electrode and reduce the interfacial impedance for all-solid-state lithium batteries (ASSLBs). However, the low ionic conductivity and poor mechanical strength restrict the development of SPEs. In this work, the chloride superionic conductor Li2ZrCl6 (LZC) is innovatively introduced into the poly(ethylene oxide) (PEO)-based SPE to address these issues since LZC is crucial for improving the ionic conductivity and enhancing the mechanical strength. The as-prepared electrolyte provides a high ionic conductivity of 5.98 x 10-4 S cm-1 at 60 degrees C and a high Li-ion transference number of 0.44. More importantly, the interaction between LZC and PEO is investigated using FT-IR and Raman spectroscopy, which is conducive to inhibiting the decomposition of PEO and beneficial to the uniform deposition of Li ions. Therefore, a minor polarization voltage of 30 mV is exhibited for the Li||Li cell after cycling for 1000 h. The LiFePO4||Li ASSLB with 1% LZC-added composite electrolyte (CPE-1% LZC) demonstrates excellent cycling performance with a capacity of 145.4 mA h g-1 after 400 cycles at 0.5 C. This work combines the advantages of chloride and polymer electrolytes, exhibiting great potential in the next generation of all-solid-state lithium metal batteries.

Automated summary

In this work, the authors innovatively introduced the chloride superionic conductor Li2ZrCl6 into the poly(ethylene oxide)-based solid-state polymer electrolyte, which effectively improved the ionic conductivity and mechanical strength. The electrolyte showed a high ionic conductivity of 5.98 x 10-4 S cm-1 and a high Li-ion transference number of 0.44. The interaction between Li2ZrCl6 and PEO was examined, inhibiting the decomposition of PEO and facilitating the uniform deposition of Li ions. The LiFePO4||Li all-solid-state lithium battery with 1% LZC-added composite electrolyte demonstrated excellent cycling performance with a capacity of 145.4 mA h g-1 after 400 cycles at 0.5 C, showing great potential for the next generation of all-solid-state lithium metal batteries.