Anion-inhibited solid framework polymer electrolyte for dendrite-free lithium metal batteries

摘要

Lithium metal shows great promise as an anode material for high-performance next-generation batteries due to its low redox potential, low weight, and high specific capacity. However, the uncontrolled growth of lithium dendrites during charge-discharge cycling limits the practical application of lithium metal anodes. In this work, an anion-inhibited solid framework polymer electrolyte (SFPE) was prepared through the polymerization of vinyl polyhedral oligomeric silsesquioxane (VPOSS) and diallyl dicarbonate (DDC) as a means to suppress lithium dendrite formation. The structure of the electrolyte was found to reduce the electric field at the anode surface by restricting the free movement of the anions (TFSI-) of the lithium salt, which facilitated the orderly, uniform, and safe deposition of lithium ions on the anode. The SFPE presented a high lithium ion transference number (0.63), a wide window of electrochemical stability (5.6 V versus Li+/Li), and high ionic conductivity (0.31 mS cm(-1)) at 25 degrees C. A LiFePO4/Li cell containing the SFPE achieved a specific discharge capacity of 165 mAh g(-1) and a capacity retention of 91.3% after 200 cycles at 0.1 C (1 C = 180 mAh g(-1)) and 25 degrees C, and the lithium anode surface remained smooth after 600 h of constant-current chargeedischarge cycling. Based on these results, this SFPE is an excellent candidate for use in high-performance lithium metal batteries. (C) 2020 Elsevier Ltd. All rights reserved.