Three-Dimension Hierarchical Al2O3 Nanosheets Wrapped LiMn2O4 with Enhanced Cycling Stability as Cathode Material for Lithium Ion Batteries

A three dimensional (3D) Al2O3 coating layer was synthesized by a facile approach including stripping and in situ self-assembly of gamma-AlOOH. The uniform flower-like Al2O3 nanosheets with high specific area largely sequesters acidic species produced by side reaction between electrode and electrolyte. The inner coating layer wrapping spinel LiMn2O4 effectively inhibits the dissolution of Mn by suppressing directive contact with electrolyte to enhance cycling stability. The rate performance is improved because of the better electrolyte storage of the assembled hierarchical architecture of the 3D coating layer affording unimpeded Li+ diffusion from electrode to electrolyte. The electrochemical results reveal the as-prepared coated LiMn2O4 sample with the amount of Al2O3 at 1 wt % exhibits superior cycle stability under room temperature even at elevated temperature. The initial specific discharge capacity is 128.5 mAh g(-1) at 0.1 C and retains 89.8% of the initial capacity after 800 cycles at 1 C rate. When cycling at 55 degrees C, the composite shows 93.6% capacity retention after 500 cycles. This facile surface modification and effective structure of coating layer can be adopted to enhance the cycling performance and thermal stability of other electrode materials for which Al2O3 plays its role.