Influence of the synthesis method on the electrochemical properties of the Li_4Ti_5O_(12) spinel in Li-half and Li-ion full-cells. A systematic comparison

摘要

To study the influence of the synthesis method on the electrochemical performances of the Li_4Ti_5O_(12) spinel (LTO) several samples have been prepared by three different synthesis procedures (sol-gel, self-combustion and solid-state). The use of the same Ti-source (TiCl_4) and strictly the same experimental conditions has allowed performing a meaningful comparison analysis. The structural characterization by X-ray diffraction shown that cubic spinels, with similar cell parameter (a_c ～ 8.35 A), were obtained for the three methods. The purity of the samples prepared by sol-gel (LTO-SG) and combustion (LTO-CB) was very high, >96%. FE-SEM studies revealed that the particle size (ps) and the particle aggregation notably changed with the synthesis method. The ps-values grow up from 301 nm for LTO-SG to 1580 nm for the sample synthesized by solid-state (LTO-SS). The comparison of the galvanostatic results permitted to demonstrate that LTO-electrochemical performances (capacity, cycleability and rate capability) strongly depend on the synthesis method. The LTO-SG sample exhibited the best electrochemical performances, with a discharge capacity of 146 mAh/g at 0.2 C, elevated cycleability and the highest rate capability. New formulation Li-ion full-cells with the synthesized LTO-samples as anode and LiCo_(2/3)Ni_(1/6)Mn_(1/6)O_2 as cathode have been assembled and studied. They have remarkable cycling performances with capacity retentions >90% after 50 cycles.