Enhanced cyclability of LiCoO2 cathodes coated with alumina derived from carboxylate?alumoxanes

Abstract

LiCoO 2 cathodes coated with Al 2 O 3 generated from carboxylate-alumoxanes have demonstrated sustainable extended cyclability. The carboxylate-alumoxanes were prepared by reacting boehmite with acetic and substituted acetic acids. TEM images of the coated powders revealed that the coatings were compact and had an average thickness of about 20 nm. XRD data on the coated materials indicated minor changes in the values of the lattice parameters, suggesting the formation of solid solutions of the composition LiAl y Co 1-y O 2 on the surface during calcination. ESCA depth profiles of the constituent elements in the coated particles support this theory. R-factor values from XRD analysis and galvanostatic cycling studies suggest that a 1.0 wt. % coating formed from a (methoxyethoxy)acetate-alumoxane enhanced the cyclability by a factor of 12. The improved performance is attributed to suppression of the cycle-limiting phase transitions accompanying the charge-discharge processes. Being without environmentally hazardous organic chemicals and by-products, the coating procedure based on carboxylate-alumoxanes is a clean and benign process for industrial exploitation.

Carbon nanocoatings on active materials for Li-ion batteries

“…For example, it can serve as a mechanical and/or (electro-)chemical protection shell for the underlying active material. Until now, mostly inorganic protective coatings have been reported [11][12][13][14][15] while no clear data about the possible * Corresponding author. Tel.…”

Effect of TiO2-coating on structure and electrochemical performance of LiCo0.2Ni0.4Mn0.4O2

“…Physical and electrochemical properties were significantly improved by ZnO [15][16], Al 2 O 3 [17][18], ZrO 2 [19][20], TiO 2 [20][21], and SiO 2 [22] X-ray diffractometry (XRD, Rigaku Rint 2200) with Cu Ka radiation (l 5 0.15406 nm) was employed to characterize the crystal structure of cathode materials. It was operated at 40 kV and 30 mA over a 2h range of 10-80u in continuous scan mode with step size 0.02u and 4.0u/min scan rate.…”

Improved electrochemical performance of LiCoO2 surface treated with Li4Ti5O12

“…: +886 In order to improve the electrochemical performance, a surface coating technique has been adapted to surmount the shortcomings practiced by the unprotected LiCoO 2 cathode material. This technique protects the surface of the cathode from faster impedance growth and dissolution (3d metal ion) into the acidic electrolyte, to achieve high specific capacity and thermal stability when cycled beyond 4.2 V. Major surface coating materials used are inert oxides such as ZrO 2 [6][7][8][9], Al 2 O 3 [5][6][7][8][9][10][11], TiO 2 [8,9,11] , SiO 2 [7,12], and Co 3 O 4 [13]. Many researchers have also attempted to use the electrochemical active oxide materials such as LiCoO 2 [14] and LiMn 2 O 4 [15,16] for coating the cathode materials, which enhanced specific capacity, cycle stability and thermal stability compared to their pristine materials.…”