High‐Voltage Nickel‐Rich NMC Cathode Material with Ionic‐Liquid‐Based Polymer Electrolytes for Rechargeable Lithium‐Metal Batteries

Abstract In lithium batteries, high‐nickel‐content layered oxide cathode materials are gaining much attention due to their high capacity and energy density. Therefore, in the present study, a LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathode material is synthesized successfully. But, these Ni‐rich cathode materials cannot be operated at high voltage with liquid electrolytes, as they give rise to some problems such as structural instability, high reactivity with electrolyte, electrochemical and thermal instability, and so forth. To suppress these problems, the synthesized ionic‐liquid‐based polymer electrolyte is used over liquid electrolyte as it reduces surface reactivity, enhances cyclic stability and, since it is sufficiently mechanically stable, helps to suppress lithium dendrites growth. Owing to the high electrochemical stability of polymer electrolytes, the performance of the Li battery is also tested at high voltage (4.8 V) and the electrochemical performances are compared at higher and lower cut‐off voltages. The Li battery provides a good capacity (164 mAh.g −1 at C/10) and energy density (611 mWh.g −1 ) at 4.8 V. In addition, the cyclability of the polymer‐based Li battery is higher, as compared to the liquid‐electrolyte‐based battery. Using the optimized polymer electrolyte, an enhanced structural and interfacial stability of the Li anode and the NMC cathode can be achieved.