Enhanced performance of interconnected LiFePO4/C microspheres with excellent multiple conductive network and subtle mesoporous structure

Lithium iron phosphate/carbon (LiFePO4/C) microspheres with an excellent multiple conductive network are synthesized using iron (III) acrylate as both iron and carbon sources. The innermost network is constructed by a uniform carbon layer on the surface of LiFePO4 primary nanoparticles, which derives from the carbonation of in-situ polymerized polyacrylic acid (PAA) layer. Moreover, the acetylene black added in spay drying process fills the voids among primary nanoparticles to construct the second conductive network. Finally, the carbon from optimized content sucrose used as binder and linker can interconnect primary nanoparticles together to form the third network. In addition, subtle mesoporous structure is formed inside the multiple carbon conductive network. The highly speed electron transfer and lithium ion transportation can be achieved simultaneously for LiFePO4/C microspheres. All these features contribute to their great rate performance (163.1 mAh g−1 at 0.1 C and 126.5 mAh g−1 at 5 C) and outstanding cycling stability (95.3% of capacity retention after 1000 cycles at 5 C/5C). The well-designed LiFePO4/C microspheres with unique structure are very promising cathode materials for rechargeable lithium ion power batteries.