Enhancing the Electrochemical Performance of a High‐Voltage LiNi 0.5 Mn 1.5 O 4 Cathode in a Carbonate‐Based Electrolyte with a Novel and Low‐Cost Functional Additive

Butyric anhydride (BA) is used as an effective functional additive to improve the electrochemical performance of a high‐voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode. In the presence of 0.5 wt % BA, the capacity retention of a LNMO/Li cell is significantly improved from 15.3 to 88.4 % after 200 cycles at 1 C. Furthermore, the rate performance of the LNMO/Li cell is also effectively enhanced, and the capacity goes up to 112 mAh g −1 even at 5 C, which is considerably higher than that of a LNMO/Li cell in electrolyte without BA additive (95.4 mAh g −1 at 5 C). Linear sweep voltammetry and cyclic voltammetry results reveal that the BA additive can be preferentially oxidized to construct a stable cathode electrolyte interphase (CEI) film on the LNMO cathode. Subsequently, the BA‐derived CEI film can alleviate the decomposition of the electrolyte and the dissolution of Mn and Ni ions from the LNMO cathode as well as maintain the structural stability of LNMO during the cycling process; this leads to outstanding electrochemical performance. Thus, this work provides an effective and low‐cost functional electrolyte for high‐voltage LNMO‐based LIBs.