Destruction behavior of carbon hybridized Li2MnSiO4 and Li2FeSiO4 nanoparticles for cathode materials

Carbon-hybridized Li2MSiO4 (M=Mn, Fe) nanoparticles were synthesized using the spray pyrolysis method subsequent to grinding and heat treatment. The carbon-hybridized Li2MnSiO4 particles exhibited excellent cycle performance up to 1.21 Li/formula-unit delithiation(charged)/lithiation(discharged) cycles. However, the discharge capacity decreased rapidly under high delithiation/lithiation conditions of more than 1.25 Li/formula-unit, although Li2FeSiO4 has better cycle stability under delithiation/lithiation of 1.5 Li/formula-unit. The local structure differences examined using XANES between Li2MnSiO4 and Li2FeSiO4 revealed that the coordination polyhedral for Mn ion changed from tetrahedron to octahedron by cycling, while that of Fe ion was maintained as a tetrahedron. Results suggest that the coordination preference of Mn ion in the structure governs the cycle performance. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.