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

Zn 2 Ti 3 O 8 , 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 Zn 2 Ti 3 O 8 has rarely been studied. In this work, a porous Zn 2 Ti 3 O 8 anode 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 Li 4 Ti 5 O 12 , TiO 2 and Li 2 ZnTi 3 O 8 . Here, for the first time, the accurate theoretical capacity of Zn 2 Ti 3 O 8 was confirmed to be 266.4 mAh/g. It was also found that both intercalation reaction and pseudocapacitance contribute to the actual capacity of Zn 2 Ti 3 O 8 , making it possibly higher than the theoretical value. Most importantly, the porous structure of Zn 2 Ti 3 O 8 not 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 Zn 2 Ti 3 O 8 that 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. The porous structure of Zn 2 Ti 3 O 8 not only promotes the intercalation reaction, but also induces high pseudocapacitance capacity, which boosts the reversible capacity. .