Electrochemical reaction mechanism of porous Zn2Ti3O8 as a high-performance pseudocapacitive anode for Li-ion batteries

ZnTiO,as a new type of anode material for lithium-ion batteries,is attracting enormous attention because of its low cost and excellent safety.Though decent capacities have been reported,the electrochemical reaction mechanism of ZnTiOhas rarely been studied.In this work,a porous ZnTiOanode with considerably high capacity(421 mAh/g at 100 mA/g and 209 mAh/g at 5000 mA/g after 1500 cycles) was reported,which is even higher than ever reported titanium-based anodes materials including LiTiO,TiOand LiZnTiO.Here,for the first time,the accurate theoretical capacity of ZnTiOwas confirmed to be 266.4 mAh/g.It was also found that both intercalation reaction and pseudocapacitance contribute to the actual capacity of ZnTiO,making it possibly higher than the theoretical value.Most importantly,the porous structure of ZnTiOnot only promotes the intercalation reaction,but also induces high pseudocapacitance capacity(225.4 mAh/g),which boosts the reversible capacity.Therefore,it is the outstanding pseudocapacitance capacity of porous ZnTiOthat accounts for high actual capacity exceeding the theoretical one.This work elucidates the superiorities of porous structure and provides an example in designing high-performance electrodes for lithium-ion batteries.