Auxiliary agent for manganese-based secondary battery and application of auxiliary agent

The invention discloses an auxiliary agent for a manganese-based secondary battery and application of the auxiliary agent. A compound in a formula I of the auxiliary agent contains a heterooxygen double bond, can participate in positive electrode interface film formation to form a polymer containing the heterooxygen double bond, and can effectively combine metal manganese ions and reduce dissolution of the metal manganese ions; and meanwhile, the additive partially dissociated on the electrolyte or the diaphragm can effectively complex the metal manganese ions, so that the reduction precipitation of the metal manganese ions on a negative electrode interface is reduced, the side reaction degree is greatly reduced, and the loss of active lithium is reduced. 本发明公开了锰基二次电池用助剂及其应用，本申请中的助剂式Ⅰ化合物含有杂氧双键，其能够参与正极界面成膜，形成含杂氧双键的聚合物，能够有效结合金属锰离子，减少金属锰离子的溶出，同时部分游离在电解液或隔膜上的助剂能够有效络合金属锰离子，从而减少金属锰离子在负极界面的还原析出，进而极大降低副反应程度减少活性锂损失。