The preparation and electro-chemical performance of lithium rich cathode material Li(Li0.3Ni0.2Mn0.5Co0.1)O2 prepared at strictly controlled pH level.

Co 3+ substituted lithium rich cathode material 0.5Li 2 MnO 3 ·0.5LiNi 0.5 Mn 0.5 O 2 , Li(Li 0.3 Ni 0.2 Mn 0.5 Co 0.1 )O 2 , was prepared at strictly controlled pH level realized by a carefully designed feeding system. The as prepared cathode material showed lamellar morphology with clearly shown edges. Less cation mixing and higher hexagonal ordering were observed indicating intact layered structure and good electrochemical performances. The first charge delivered a total capacity of ca. 328 mAh g −1 and the subsequent discharge sent a capacity of 238 mAh g −1 back. Except for the initial several cycles, the fading of the discharge capacity was limited. A discharge capacity of 166 mAh g −1 was still reserved after 50 cycles. The rate performance was also improved. The last cycle of each current density, namely 0.1 C, 0.2 C, 0.5 C, 1 C and 2 C, delivered a capacity of ca. 226 mAh g −1 , ca. 191 mAh g −1 , ca. 160 mAh g −1 , ca. 135 mAh g −1 and ca. 110 mAh g −1 , respectively. When the current density was back to 0.1 C, ca. 80% of the initial discharge capacity, nearly 200 mAh g −1 , was regained. [ABSTRACT FROM AUTHOR]