Hierarchical LiMnPO4 center dot Li3V2(PO4)(3)/C/rGO nanocomposites as superior-rate and long-life cathodes for lithium ion batteries

摘要

The nanosized LiMnPO4 center dot Li3V2(PO4)(3)/carbon/graphene (LMP center dot LVP/C/G) composite is synthesized via a sol-gel method combined with freeze-drying. It is revealed that the composite is consisted of monoclinic Li3V2(PO4)(3) and orthorhombic olivine-type LiMnPO4, which are homogeneously distributed in this mixture. While the LMP center dot LVP nanoparticles are intimately wrapped by a thin carbon layer. Particularly, the graphene nanosheets are closely coating on the LMP center dot LVP/C particles and constructing a highly conductively network, which exert significantly influence on the particle morphology with nanosize and rate capability with excellent performance for LMP center dot LVP/C/G composite. Due to the smaller polarization and higher Li+ diffusion induced by this hierarchical structure, the LMP center dot LVP/C/G composite delivers 116.3 mAh g(-1) at ultrahigh rate of 10C, and ultrolong cycling life with capacity retention of 85.2% after 500 cycles. The synergistical effect between LMP center dot LVP and dual carbon wrapping with well-designed hierarchical structure provides an effective strategy to improve Li+ intercalation performance for cathode materials. (C) 2018 Published by Elsevier B.V.