The Mechanism Study of TMSP Additive in the Lithium-Ion Battery

Lingli Kong, Zhijiang Su, Junkui Gao, Jie Sun Tianjin Lishen battery Joint-Stock Co. Ltd, 6 Lanyuan Road, Huayuan Hi-Tech Industry Park, China Introduction To improve the safety of Li-ion batteries, considerable effort has been focused on the development of flame-retardant additive[1]. In our recent work, we found that reasonable amount of Tris(trimethylsilyl) phosphate (TMSP) not only can improve the thermal stability and safety of battery, but also can advance the cycle performance ,especially at low temp. So we assume that the additive TMSP participates in the formation of SEI on graphite anode or LiCoO2 cathode. In this study, we emphasize on the mechanism study of TMSP on the surface of cathode and anode. Experimental About 1M LiPF6 in a 1:1:1(v/v) mixture of EC, EMC, DEC was used as the standard electrolyte, and 0.5wt% TMSP was added to the standard electrolyte. Li/graphite, Li/LiCoO2 and graphite/ LiCoO2 423450 (950mAh) were assembled in dry room with the dew point of -40 . The compatibility of the TMSP with anode or cathode was measured by CV, EIS was used to measure the impedance of coin cell(Li/graphite or Li/LiCoO2), which was used after 3 cycles. The electrode was removed from 423450 after 10cycles in dry room and washed with DMC, then dried at room temperature in vacuum. The surface morphology of cathode and surface was observed by SEM, the surface composition was analyzed by XPS.