In situ construction of a P-doped TiO2/Ti3C2Tx heterostructure with local site optimization to improve Li-O2 battery performance

The performance of Li-O2 batteries is seriously limited by the sluggish kinetics of the mass transition in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). To explore a useful strategy to overcome these limitations, herein, we constructed a P-doped TiO2/Ti3C2Tx heterostructure (PTT) with local active site optimization, in which the highly conductive substrate anchored the P-TiO2 nanoparticles with a selective adsorption and conversion of LiOx. In contrast to the TiO2/Ti3C2Tx heterostructure with a relatively uniform active site inducing typical toroidal Li2O2, the introduction of P-doping generates a unique nanosheet array Li2O2 on the PTT surface as a discharge product. This unique structure is endowed with a shorter Li+ diffusion path and benefits mass transfer in ORR and OER, facilitating the reaction kinetics. It presents obviously enhanced battery performance with a high specific capacity of 13,482 mAh g−1 and decreased discharge–charge overpotential, as well as superior cycling stability of 190 cycles. Furthermore, this novel and efficient electrocatalyst can stably operate for more than 650 cycles at 1000 mA g−1 with the addition of a LiI redox mediator. This study provides new insight into high-performance electrocatalyst design in Li2O2 related battery system.