Combustion synthesis and electrochemical properties of LiNi1/3Col/3Mnl/3BrxO2-x and LiNi1/3Col/3Mnl/3BrxO2-x/graphene cathode material for Li-ion batteries
School of Materials Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009, P R China
* Corresponding author: Ji-ping ZHU; Tel:18919665197; E-mail: email@example.com
The layered LiNi1/3Co1/3Mn1/3BrxO2-x (0≤x≤0.09) cathode materials were prepared by a combustion method. The XRD results indicate that the Br-doped LiNi1/3Mn1/3Co1/3O2 has the same layered structure as the pristine LiNi1/3Mn1/3Co1/3O2. FE-SEM results indicate that the particle size distribution of samples is uniform. Electrochemical tests reveal that Br-doped samples exhibit higher discharge capacity and rate capability compared with the pristine, especially the LiNi1/3Co1/3Mn1/3Br0.05O1.95 sample shows initial discharge capacity, which can reach to 175.4 and 166.4mAh/g at 0.5 and 1.0C, respectively. Finally, an electronically conducting 2D network of graphene was introduced into LiNi1/3Co1/3Mn1/3Br0.05O1.95 cathode material. The electrochemical properties of the materials were investigated by charge-discharge tests and electrochemical impedance spectroscopy. The charge-discharge tests demonstrate that this sample has better cycle stability than LiNi1/3Co1/3Mn1/3Br0.05O1.95 which can be attributed to the excellent electronic conductivity and stable chemical properties of graphene. The EIS results reveal that the graphene coated greatly decreases the resistance of lithium batteries, especially the charge transfer resistance which can be attributed to the significantly improved electronic conductivity.
Key words: LiNi1/3Mn1/3Co1/3O2 / Br-doping / graphene / combustion synthesis
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