Rational design of a novel polypyrrole-coated and zirconium-doped lithium vanadium phosphate with outstanding rate performance for lithium-ion storage

The inferior electrical conductivity seriously prevents the application of monoclinic Li3V2(PO4)(3) (LVP) cathode in lithium energy storage. In this research, we introduce a promising strategy of polypyrrole coating and Zr4+ doping to promote the conductivity of LVP material. The Zr4+-doped and polypyrrole-coated LVP (LVZ(x)P@PPy) electrode is synthesized by a facile way followed by an in-situ pyrrole polymerization procedure for the first time. The substitution of Zr4+ in V3+ site can enlarge the lattice volume of LVP, providing a big diffusion channel for Li+ extraction and insertion. Besides, Zr4+ doping can also promote the intrinsic conductivity of LVP, whilst polypyrrole film can greatly promote the apparent conductivity. Therefore, the as-fabricated LVZ(x)P@PPy electrode possesses outstanding rate property for lithium energy storage. Especially, LVZ(5%)P@PPy displays the specific capacities of 131.5 and 115.2 mA h g(-1) at 0.1 and 5C respectively between 3 and 4.3 V. Meanwhile, it shows the high capacity retention of 95.7% over 400 cycles at 10C in the potential range of 3 similar to 4.8 V.

Automated summary

In this research, a promising strategy of polypyrrole coating and Zr4+ doping was introduced to improve the conductivity of LVP material. The Zr4+-doped and polypyrrole-coated LVZ(x)P@PPy electrode was synthesized by a facile way followed by an in-situ pyrrole polymerization procedure. The as-fabricated electrode exhibited outstanding rate property for lithium energy storage.