An electrolyte additive with boron-nitrogen-oxygen alkyl group enabled stable cycling for high voltage LiNi0.5Mn1.5O4 cathode in lithium-ion battery

An electrolyte additive with boron-nitrogen-oxygen groups for high voltage (5 V) LiNi0.5Mn1.5O4 (LNMO) electrode is investigated by electrochemical performance, material analysis and density function theory first principles calculation (DFT). The 1 wt% Methylboronic acid MIDA ester (ADM) additive in ethylene carbonate and dimethyl carbonate (EC/DMC) electrolyte for LNMO cathode shows a paramount discharge capacity retention of 96% (15% in without additive) after 25 cycles at 75 mA g−1 and 40 °C, also inhibits the impedance growth during cycling. By increasing the charge/discharge current density from 15 mA g−1 to 450 mA g−1, the rate capability of LNMO cell with ADM additive is ca. 40%, while the counterpart is only 1.5%. By characterizations, the results interpret that the ADM additive decomposes and participates in the reaction pathway of cathode electrolyte interface (CEI) formation, which are more protective and resistant to electrolyte oxidative decompositions, and more potent in maintaining the structural integrity of nickel (Ni), manganese (Mn), and PF6−.