Investigation of Tetravalent Cation Doping with (M = Sn4+, Zr4+, and Ge4+) on the Electrochemical Properties of Monoclinic Li3V2(PO4)3 Using First-Principles Calculations

Monoclinic Li3V2(PO4)(3) (LVP) is a very attractive candidate for next generation Li-ion batteries owing to its low cost, sustainability, high thermal and electrochemical stability, high operational voltage (up to 4.8 V vs Li+/Li), larger Li+ ion diffusion coefficient (similar to 10(-9)-10(-10) cm(2).s(-1)), and high theoretical capacity (197 mAh.g(-1) from 3 Li). Nevertheless, LVP suffers from low intrinsic electrical conductivity (similar to 10(-8) S.cm(-1)). Doping LVP with Sn4+, Zr4+ or Ge4+ has been shown to greatly enhance its electrochemical performance. However, the underlying mechanisms behind this improvement is not yet fully understood. In this work, we conduct first-principles calculations on undoped and (Sn4+, Zr4+ or Ge4+)-doped LVP and we propose explanations for the experimentally observed structural stability of the doped LVP, as well as the increase in the Li+ ionic conductivity, by analyzing its calculated structural and magnetic properties. By investigating the electronic structure of undoped and doped LVP systems, we propose a mechanism that explains the improvement of the electrical conductivity of (Sn, Zr or Ge)-doped LVP.

Automated summary

Studies have shown that doping with Sn4+, Zr4+, or Ge4+ can enhance the electrochemical performance of LVP, but the underlying mechanisms behind this improvement are not fully understood. This study conducts first-principles calculations to explain the effects of doping on the electronic structure and electrical conductivity of LVP.