Lithium extraction from salt lakes has become a hot research issue in recent years, and LiMn 2 O 4 -based electrochemical lithium extraction is considered to be one of the most promising technologies for application. However, LiMn 2 O 4 limits its further application due to the dissolution of Mn and the Jahn-Teller effect. In this study, a LiNi 0.05 Mn 1.95 O 4 (LNMO-0.05) lithium-extraction electrode material with truncated octahedral characteristics was prepared. The special crystal surface structure enhanced the diffusion and adsorption rates of Li + , whereas Ni doping effectively suppressed the Jahn-Teller effect, and the two mechanisms synergistically enhanced the lithium extraction performance of LMO. In lithium extraction from East Taijiner brine with an Mg/Li ratio of 46, LNMO-0.05 showed excellent ion selectivity (α Mg-Li = 214.08), high lithium extraction capacity (20.99 mg/g) and no significant capacity decay occurred after 10 cycles. These excellent properties make the LNMO-0.05 electrode suitable for industrial electrochemical lithium extraction.
Wangqiong Xu,Hongli Bai,Qiling Li,Tao Feng,Junming Guo,Lili Feng,Chang-wei Su,Wei Bai,Xiaofang Liu
Nano-LiNi 0.05 Mn 1.95 O 4 cathode materials with nano-sized particles were successfully synthesized by a low temperature molten-salt combustion method at 400 °C for 1 h and then two-stage calcination at 600 °C for 3 h. The crystal structures and morphologies of nano-LiNi 0.05 Mn 1.95 O 4 were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). All obtained samples with good crystallinity were identified as the cubic spinel structure of LiMn 2 O 4 . The lattice parameters and the particle size of samples decreased as the Ni doped. The effects of Ni 2+ ion doping on the electrochemical properties of nano-LiNi 0.05 Mn 1.95 O 4 were investigated by a galvanostatic charge-discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the nano-LiNi 0.05 Mn 1.95 O 4 sample exhibited the initial discharge capacity of 112.4 mAh g -1 with capacity retention of 80.7% after 1000 cycles at 1.0 C (1 C = 148.0 mAh g -1 ). In addition, the nano-LiNi 0.05 Mn 1.95 O 4 sample exhibited good rate capabilities at different current densities from 0.5 C to 5.0 C. These improvements are attributed to the synergistic effects of the nano-structure and nickel doping of the LiNi 0.05 Mn 1.95 O 4 sample.
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