Electrochemical investigation of double layer surface-functionalized Li-NMC cathode with nano-composite gel polymer electrolyte for Li-battery applications

Abstract

A long cycle-stability and safety is key requirement for the large-scale application of rechargeable Li-batteries. In this study, a thin double-layer (reduce graphene oxide and Li2MoO4) coated Li-NMC111 cathode is successfully synthesized which delivers improved electrochemical performance such as higher specific energy density and better rate capability, as compared to the pristine Li-NMC111. Furthermore, a freestanding/flexible nano-composite gel polymer electrolyte (NGPEs) is successfully prepared by solution cast technique and found suitable for high-temperature Li-battery applications. The developed 5 wt.% MCM-41 containing NGPE (NGPE#1) not only facilitates enhanced Li-ion conductivity of ∼4.4 ✗ 10−3 S cm−1 at 30 °C but also prevents uncontrolled lithium dendrite growth. The RGO-wrapped Li2MoO4@Li-NMC111 cathode with optimized NGPE#1 delivers high specific discharge capacity (∼211 mAh g− 1 at 0.2C and ∼157 mAh g− 1 at 0.5C) and specific energy density (∼728 mWh g− 1 at 0.2C and ∼520 mWh g− 1 at 0.5C) as compared to pristine Li-NMC111 cathode. Moreover, after 100 cycles, the discharge capacity of RGO-wrapped Li2MoO4@Li-NMC111 with optimized NGPE#1 is obtained ∼150 mAh g− 1 at 0.5C, with 75% capacity retention of the maximum capacity. In addition, at 70 °C, the specific discharge capacity of Li/RGO-wrapped Li2MoO4@Li-NMC111 cell with optimized NGPE#1 is obtained ∼186 mAh g− 1 at 0.5C.