LiMn0.8Fe0.2PO4/Carbon Nanospheres@Graphene Nanoribbons Prepared by the Biomineralization Process as the Cathode for Lithium-Ion Batteries

Biomineralization technology is a feasible and promising route to fabricate phosphate cathode materials with hierarchical nanostructure for high-performance lithium-ion batteries (LIBs). In this work, to improve the electrochemical performance of LiMn_0.8Fe_0.2PO₄ (LMFP), hierarchical LMFP/carbon nanospheres are wrapped in situ with N-doped graphene nanoribbons (GNRs) via biomineralization by using yeast cells as the nucleating agent, self-assembly template, and carbon source. Such LMFP nanospheres are assembled by more fine nanocrystals with an average size of 18.3 nm. Moreover, the preferential crystal orientation along the [010] direction and certain antisite lattice defects can be identified in LMFP nanocrystals, which promote rapid diffusion of Li ions and generate more active sites for the electrochemical reaction. Moreover, such N-doped GNR networks, wrapped between LMFP/carbon nanospheres, are beneficial to the fast mobility of electrons and good penetration of the electrolyte. As expected, the as-prepared LMFP/carbon multicomposite presents the outstanding electrochemical performance, including the large initial discharge capacity of 168.8 mA h g^-1, good rate capability, and excellent long-term cycling stability over 2000 cycles. Therefore, the biomineralization method is demonstrated here to be effective to manipulate the microstructure of multicomponent phosphate cathode materials based on the requirement of capacity, rate capability, and cycle stability for LIBs.