LAUSR

Abstract LiNi0.5Co0.2Mn0.3O2 (LNCM) cathode surfaces coated with 1–2 wt% Bismaleimide/trithiocyanuric acid (BMI/TCA, BT) oligomer as an additive are successfully prepared for lithium-ion batteries (LIBs). Coin cells comprising the LNCM electrode with 1 wt% BT (1 wt% BT@LNCM) demonstrate similar capacity retention of ca. 91% to the bare LNCM cells at 0.1C for 30 cycles. Electrochemical impedance results confirm that the 1 wt% BT@LNCM cells exhibit identical Li+ diffusion coefficients of ca. 1.1 × 10−10 cm2 s−1 to the bare LNCM cells. TGA/DSC thermal studies show that the delithiated 1 wt% BT@LNCM sample decomposes at a higher temperature than the bare one without electrolyte (ca. 317 vs. 284˚C). In addition, the total heat generation (Qt) of the 1 wt% BT@LNCM electrode with electrolyte is much lower than that of the bare electrode (ca. 599 vs. 824 J g−1). There was strong evidence that the surface coating of BT oligomer on the LNCM could not only reduce the generated heat, but also extended the decomposition temperature. Furthermore, the Qt of the 1 wt% BT@LNCM cells performed at 1C isothermally is reduced by ca. 17% via operando micro-calorimetry; the Qt of the 1 wt% BT@LNCM cells at fully-charged state is also smaller (ca. 3–5%) when the temperature elevates to 300 °C. In summary, LNCM523 cathode materials coated with the 1 wt% BT oligomer show potential for high-energy LIBs application without suffering thermal runaway.