As one of the most common and dangerous safety issues of lithium ion batteries (LIBs), overcharge is a condition that the electricity flow is forced through a cell after reaching its full capacity. Consequently, the cell voltage will be raised dramatically and soon go beyond the electrochemical window of the electrolyte, leading to thermal runaway or even explosion. Several protection methods have been proposed to address this issue. The most effective and promising strategy is to incorporate the electrolyte additive, called redox shuttles, into the battery electrolyte to provide an intrinsic protection. Although a number of redox shuttles have been evaluated, only a few show effective protection for 4V LIBs. In this presentation, two novel redox shuttle molecules were proposed through introducing the organophosphine oxide groups into the dimethoxybenzene platform, a family of which has drawn significant attention due to their excellent electrochemical stability for overcharge protection. The bulky organophosphine groups not only provide the desired steric effect to protect the radical cation but also increase the redox potential to 4.5 V, which is suitable for overcharge protection of 4V LIBs. The synthesis of those two molecules as well as electrochemical reversibility, overcharge test and DFT calculations will be discussed.

Novel organophosphine oxide based redox shuttle additives for 4V lithium ion batteries

249th National Meeting (2015)

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