Improving the structure stability and electrochemical performance of Li2MnSiO4/C cathode materials by Ti-doping and porous microstructure

Li2MnSiO4 cathode material suffers from structure collapse and thus rapid capacity fading during cycling. Here, we employed the stable [TiO6] ligands as a local pillaring framework to improve the structural stability. Porous Li2MnSi1-xTixO4/C nanoparticles were successfully synthesized by employing SBA-15 as Si source. Rietveld refinement revealed Ti substitution caused the phase composition transition (partial Pmnb to Pmn2(1) phase), which contributed to higher charge/discharge capacity. XPS confirmed the positions of Ti4+ and the formation of [TiO6] octahedrons. 15 mol% Ti doped sample (S-LMST) showed a highest specific surface area of 114.25 m(2) g(-1) and delivered a highest initial discharge capacity of 182.7 mAh g(-1) under 1.5-4.8 V. Interestingly, S-LMST electrode presented excellent cycling stability, especially retaining similar to 94% of initial discharge capacity after 8th cycles, while pristine Li2MnSiO4 only retained similar to 55%. Additionally, S-LMST electrode exhibited higher discharge capacity under lower cut-off voltage. The maximal initial discharge capacity can reach to 259.7 mAh g(-1) in 1.5-4.6 V. The enhanced cycling stability can be mainly ascribed to the pillaring effect of [TiO6] octahedrons and the decreased charge transfer resistance, as well as the improved Li+ diffusion coefficient due to porous structure. (C) 2017 Elsevier B.V. All rights reserved.