Isocyanoethyl Methacrylate (IMA) as a Bifunctional Electrolyte Additive for LiNi0.8Co0.1Mn0.1O2/Graphite Batteries with Enhanced Performance

Abstract By now, as the promising high‐energy cathode materials of lithium‐ion batteries (LIBs), the high‐nickel LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) still have technical problems such as poor electrode‐electrolyte interface stability and sensitivity to H 2 O and HF in the electrolyte to be solved. In this work, isocyanoethyl methacrylate (IMA) containing −N=C=O group is developed as a bifunctional electrolyte additive through the film‐forming, H 2 O removal, and HF reduction to modify the electrode‐electrolyte interfaces and improve the performance of NCM811/graphite LIBs. After 450 cycles under the normal voltage range of 2.75 to 4.20 V, the capacity retention of the battery with 0.5 wt.% IMA additive increases from 50.7 % to 78.0 % compared to the battery without the additive. And under the high voltage range of 2.75 to 4.40 V, the capacity retention of the battery with IMA increases from 62.8 % to 81.9 % after 150 cycles. It is demonstrated that the IMA additive as the H 2 O and HF scavenger of electrolyte also facilitate the electrochemical oxidation‐reduction reactions on two electrodes to form high‐quality interfacial films, which stabilizes the anode and cathode interfaces and subsequently improves the cycling performance of the batteries. These results show that the electrolyte with IMA additive has promising prospects in the application of high‐nickel NCM‐based LIBs and provide the idea to evaluate the organic molecules containing −N=C=O group as the functional electrolyte additives as well.