Dual application of non-fluorinated polymer: Influence on mitigating dendrite growth and structural integrity of high energy density lithium metal battery

Abstract

Fluorine-based polyvinylidene difluoride is one of the most widely used binders for Lithium-ion batteries due to good thermal and electrochemical stability. However, PVDF has several significant disadvantages, which could greatly restrict its practical application. PVDF is not suitable for Lithium metal batteries with cutting-edge cathode materials and lithium metal anode because of the swelling and degradation of electrode particles as well as unstable solid electrolyte interface on the Lithium anode in liquid electrolytes at elevated temperatures. Herein, the non-fluorinated polymer of Poly-1-Vinyl-2-pyrrolidinone-crosslinked-prop-2-enoic acid is developed as both binders for Ni-rich LiNi0.8Mn0.1Co0.1O2 cathode and artificial SEI layer for stable lithium-metal anodes, enabling all Li metal batteries, with excellent mechanical integrity. As a binder, Ni-rich NMC cathode (LiNi0.8Mn0.1Co0.1O2) displays an initial discharging capacity of 232.6 mAh g−1 with Coulombic efficiency of nearly 89.9 % compared to PVDF (77.6 %). It also demonstrated good cycling stability even after 200 cycles by exhibiting a 146.2 mAh g−1 discharging capacity at a 1C rate with 92 % capacity retention. In addition, Li/Poly-VPCPEA@PP/Li symmetric cell revealed a low voltage hysteresis of 10 mV over 1000 h for 1 mA cm2 and 200 h for 5 mA cm−2.