Novel organic anode based on o-benzene active material for high-performance lithium ion batteries

Abstract

Organic redox-active materials are investigation hotspots for lithium ion storage due to their structural diversity and tunability. A large number of researches have focused on the organic materials of benzene para-substitution type. There are little investigations on benzene ortho-substitution type organic materials. Benzene ortho-substitution redox molecules are generally considered to be too close to the functional group to fully react, and conjugated structure is not as stable as that of para-substitution. However, we reported dilithium phthalate (Li2PA) anode active material for lithium ion battery. Interestingly, Li2PA anode has an excess capacity and reaches four-electrons reaction, and the lithium ions storage mechanism is explored: not only the two adjacent conjugated carbonyls can fully react, but also the rearranged benzene ring can accept two Li + ions. Li2PA anode has a high specific capacity of 674 mA h g−1 at 60 mA g−1, with 91.7% capacity retention after 125 cycles (cycled for 4 months). Furthermore, it achieves high-rate capability, holding the specific capacity of 110 mA h g−1 at 4000 mA g−1. This research shows that Li2PA can be used as organic active material for anode, opening up new possibility for organic anode development.