Enhanced electrochemical performance of Li_(1.18)Ni_(0.15)Co_(0.15)Mn_(0.52)O_2 cathode modified with aluminosilicate solid acid

摘要

Li-rich cathode material Li_(1.18)Ni_(0.15)Co_(0.15)Mn_(0.52)O_2 is prepared by a sol-gel method and modified with aluminosilicate solid acid (Al_2O_3·SiO_2) via an ultrasonic impregnation process. Compared with the pristine and Al_2O_3/SiO_2-sole-modified counterparts, the Al_2O_3 SiO_2 coating layer with high acid center strength on Li_(1.18)Ni_(0.15)Co_(0.15)Mn_(0.52)O_2 material exhibits overall improved electrochemical performance. Galvanostatic charge-discharge tests at the current density of 200 mA g~(-1) displays the highest capacity retention of 72.5% and voltage retention of 95.1% after 200 cycles for Al_2O_3 SiO_2-coated material. Meanwhile, a high rate capability of 99.2 mAh g~(-1) after 300 cycles is obtained with a good retention of 65.7% at the current density of 1 Ag~(-1). The analysis of dQ/dV plots indicates the strong acid center strength of Al_2O_3 SiO_2 coating layer on Li_(1.18)Ni_(0.15)Co_(0.15)Mn_(0.52)O_2 cathode material can be favor of suppressing the voltage decay and reducing the side reactions between the electrode and the electrolyte.