In situ growing conductive polyaniline (PANi) has been regarded as a functional binder to enhance the performance of silicon based anodes in half cells, while few papers discussing the influence of Mn2+ from cathode on full cells. In this paper, the effects of Mn2+ on NSi@PANi electrodes in both half and full cells are investigated, and the mechanism for the fast capacity fade of LiMn2O4/NSi@PANi full cell is elucidated. Results reveal that the full cell will significant accelerate the capacity fade of NSi@PANi anode, and the extra consumption of active Li+ and electrolytes caused by the deposited Mn2+ on silicon anodes in lithium manganate (LMO)/NSi@PANi full cells is confirmed as the main reason of the capacity fade and lower coulombic efficiency for the excessive growth of solid electrolyte interphase.
It is still unknown how dissolved manganese ions affect the silicon anode's electrochemical performance in thelithium-ion batteries (LIBs). In this study, the damage mechanism of Mn2+ to silicon electrode in LIBs was studied by adding Mn2+ into electrolyte system to simulate the electrochemical environment. Through the comparison between full cell and half cell, the mechanism of the capacity fading of silicon electrode is revealed. In order to compare the amount of SEI growth on silicon anode during the cycling, the heat flux of SEi was analyzed by DSC. Experiments show that the Mn2+ could make SEI more fragile, more easily break, and then accelerate the SEI thickening. So Mn2+ could reduce the coulomb efficiency and electrochemical capacity of the silicon anode. Electrochemical capacity of negative electrode in full cell decays much faster than that in half-cell environment, whose coulomb efficiency of full cell is only 32%, while that of the half cell is higher than 97%. In addition to the damage of the Mn2+ to silicon anode, the depletion of active lithium ion source in full cell is also an important reason for the rapid decline of electrochemical capacity.