Charge rate influence on the electrochemical performance of LiFePO4 electrode with redox shuttle additive in electrolyte

Overcharge performance of LiFePO4 cells is investigated through adding 2, 5-ditertbutyl 1, 4-dimethoxybenzene (DDB) as redox shuttle into electrolyte (RS electrolyte) at different charge rate. RS electrolytes with DDB works well as overcharge protection at low charge rate of less than 0.1 C. Novel charge/discharge characteristics are observed when charge rate increases in the cell with RS electrolyte. Especially, larger discharge capacities are obtained at the same discharge rate after charge rate gets higher than 0.1 C rate. Discharge capacity is larger in the cell with RS electrolyte than that in the cell without RS electrolyte at the same charge and discharge rate. At the same charge rate, cells with RS electrolyte have better cycling performances and larger discharge capacity than that with conventional electrolyte. These indicate that DDB accumulates in cathode with cycling and influences electrode-electrolyte interface reactions.