Synthesis and electrochemical properties of layered Li_(1.0)Mn_(0.82)Ni_(0.10)Ti_(0.08)O_2 prepared by chemical lithium insertion

摘要

The novel Li_xMn_yNi_zTi_(1-y-z)O_2 compounds were prepared by Na~+/Li~+ ion-exchange and chemical lithium insertion. The eight products were characterized using X-ray diffraction, ICP-AES, SEM, and electrochemical measurements. All the samples were adopted the layered rock-salt type structure. The electrochemical properties of Li_(0.6)Mn_(0.82)Ni_(0.10)Ti_(0.08)O_2 sample exhibited the best capacity retention of 87% at 20th charge-discharge test in the voltage range of 1.5 and 5.0 V of all the present samples. The extra lithium was added by chemical lithium insertion using Lil and then fully occupied Li_(1.0)Mn_(0.82)Ni_(0.10)Ti_(0.08)O_2 in lithium site was obtained. The initial charge and discharge capacities of Li/Li_(1.0)Mn_(0.82)Ni_(0.10)Ti_(0.08)O_2 cell were 250 mAh g~(-1) and 244 mAh g~(-1) respectively, with the first coulombic efficiency of 98% between 2.0 and 4.8 V. The graphite/Li_(1.0)Mn_(0.82)Ni_(0.10)Ti_(0.08)O_2 cell indicated the first discharge capacity of 208 mAh g~(-1) at 1.8 V after charging up to 4.7 V. The irreversible capacity loss of 39 mAh g~(-1) was ascribed to the formation of a solid-electrolyte interface (SE1). The Li_(1.0)Mn_(0.82)Ni_(0.10)Ti_(0.08)O_2 is one of the promising materials for positive electrode material in lithium ion batteries for the view point of high capacity and coulombic efficiency.