An oxygen-deficient Li2ZnTi3O8 anode for high-performance lithium storage

Abstract

Li₂ZnTi₃O₈ (LZTO) as an anode of lithium-ion batteries has been attracting great interest. However, its low electrical conductivity is the biggest obstacle to the practical application of LZTO. The presence of Ti³⁺ can improve the electronic conductivity of LZTO via the introduction of oxygen vacancies (OVs). Nevertheless, excess OVs can cause severe lattice distortion and then worsen the electrochemical performance of LZTO. In this study, defective LZTO anodes with different concentrations of OVs are fabricated by a practical solid-state method. The effects of OVs on LZTO are investigated by experiments and first-principles calculations. The results show that the presence of OVs promotes random Zn/Ti distribution. LZTO with an appropriate concentration of OVs (LZTO-FA) can stabilize the structure, decrease the diffusion barriers of Li⁺ ions and transfer resistance. Therefore, LZTO-FA has good electrochemical performance from 0 to 55 °C. More importantly, compared with LZTO with a perfect structure, the intercalation potential of LZTO-FA decreases as shown by the calculations. Therefore, the energy densities of the full cells can be improved using LZTO-FA as the anode. So, the findings can be instructive in the improvement of the electrochemical performance of LZTO via the introduction of OVs.