Ultrahigh rate capability of manganese based olivine cathodes enabled by interfacial electron transport enhancement

Abstract

Manganese-based Olivine is a promising cathode candidate with high energy and low cost for Li-ion batteries (LIBs). Its rate capability and cyclability challenges still remain even with nano-size and carbon coating. Herein, an ultrahigh rate performance is achieved by introducing an affinitive conductor to enhance the interfacial electron transport of LiMn0.7Fe0.3PO4via Li3V2(PO4)3. It is found that the Li3V2(PO4)3 facilitates sp2 hybridization to form a highly conductive carbon coating during the carbonized process. The composite 0.9LiMn0.7Fe0.3PO4·0.1Li3V2(PO4)3 can deliver a capacity of 90.9 mAh g−1 and power density of 11444 W kg−1 at 50 C-rate. Both in situ X-ray diffraction and conductive-atomic force microscopy are conducted to understand the synergetic effect between LiMn0.7Fe0.3PO4 and Li3V2(PO4)3. The results suggest that the interfacial electron transfer between LiMn0.7Fe0.3PO4 particles and the electron conducting medium, such as binder/carbon black composite, is greatly improved so that the highly Li+ conductive nature of olivine materials can be fully unleashed. This work demonstrates the importance of efficient interfacial electron transfer to the active cathode particles, and opens up a new venue for the rational design of high-energy and high-power batteries.