Microwave Fusion of the Composite LiMn1.6Ni0.4O4-LiFePO4 /C to Improve the Stability of Spinel Phase

Abstract

Lithium-ion batteries are a promissory technology for energy storage devices in electric vehicles and renewable energy generation systems. Lithium nickel manganese oxides (LMNO, spinel structure) are promising cathode materials for lithium-ion batteries because of their high potential (4.7V vs. Li/Li+, 147 mAhg-1), moderate thermal stability and environmental friendliness. However, their chemical stability and electronic conductivity needs to be improved for practical applications. The microwave fusion of composite material LiMn1.6Ni0.4 (LMNO, spinel) coated with LiFePO4 /C (LFP, olivine structure) is studied in order improve the stability of active material without reducing the active sites for lithium intercalation. Synchrotron diffractions shows superior crystallographic order and no further impurities precipitation for the composite material heated at 10W (see Figure 1). Electrochemical characterizations shows high cycled stability for LMNO-2LFP/C heated at 10W (97% after 100th cycles) (see Figure 2). The composite materials heated at 100W presents lower discharge capacity due to the changes in the lattice parameters and impurities precipitation during microwave heating. Sincrotron diffraction after 60th cycle in composite material heated at 10W shows the same lattice parameters for spinel phase and the reductions of lattice parameters for olivine structure in “b” direction. Figure 1