High performance lithium-ion batteries (LIBs) have attracted considerable attention as essential energy sources for high-technology electrical devices such as electrical vehicles, unmanned drones, uninterruptible power supply, and artificial intelligence robots because of their high energy density (150-250 Wh/kg), long lifetime (> 500 cycles), low toxicity, and low memory effects. Of the high-performance LIB components, cathode materials have a significant effect on the capacity, lifetime, energy density, power density, and operating conditions of high-performance LIBs. This is because cathode materials have limitations with respect to a lower specific capacity and cycling stability as compared to anode materials. In addition, cathode materials present difficulties when used with LIBs in electric vehicles because of their poor rate performance. Therefore, this study summarizes the structural and electrochemical properties of cathode materials for LIBs used in electric vehicles. In addition, we consider unique strategies to improve their structural and electrochemical properties.
Citations
Layered LiNi0.83Co0.11Mn0.06O2 cathode materials single- and dual-doped by the rare-earth elements Ce and Nd are successfully fabricated by using a coprecipitation-assisted solid-phase method. For comparison purposes, nondoping pristine LiNi0.83Co0.11Mn0.06O2 cathode material is also prepared using the same method. The crystal structure, morphology, and electrochemical performances are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) mapping, and electrochemical techniques. The XRD data demonstrates that all prepared samples maintain a typical α-NaFeO2-layered structure with the
Citations
Ni1/3Co1/3Mn1/3(OH)2 powders have been synthesized in a continuously stirred tank reactor via a co-precipitation reaction between aqueous metal sulfates and NaOH using NH4OH as a chelating agent. The co-precipitation temperature is varied in the range of 30-80°C. Calcination of the prepared precursors with Li2CO3 for 8 h at 1000°C in air results in Li Ni1/3Co1/3Mn1/3O2 powders. Two kinds of obtained powders have been characterized by X-ray diffraction (XRD), scanning electron microscopy, particle size analyzer, and tap density measurements. The co-precipitation temperature does not differentiate the XRD patterns of precursors as well as their final powders. Precursor powders are spherical and dense, consisting of numerous acicular or flaky primary particles. The precursors obtained at 70 and 80°C possess bigger primary particles having more irregular shapes than those at lower temperatures. This is related to the lower tap density measured for the former. The final powders show a similar tendency in terms of primary particle shape and tap density. Electrochemical characterization shows that the initial charge/discharge capacities and cycle life of final powders from the precursors obtained at 70 and 80°C are inferior to those at 50°C. It is concluded that the optimum co-precipitation temperature is around 50°C.
Citations
As precursors of cathode materials for lithium ion batteries, Ni1/3Co1/3Mn1/3(OH)2 powders are prepared in a continuously stirred tank reactor via a co-precipitation reaction between aqueous metal sulfates and NaOH in the presence of NH4OH in air or nitrogen ambient. Calcination of the precursors with Li2CO3 for 8 h at 1,000°C in air produces dense spherical cathode materials. The precursors and final powders are characterized by X-ray diffraction (XRD), scanning electron microscopy, particle size analysis, tap density measurement, and thermal gravimetric analysis. The precursor powders obtained in air or nitrogen ambient show XRD patterns identified as Ni1/3Co1/3Mn1/3(OH)2. Regardless of the atmosphere, the final powders exhibit the XRD patterns of LiNi1/3Co1/3Mn1/3O2 (NCM). The precursor powders obtained in air have larger particle size and lower tap density than those obtained in nitrogen ambient. NCM powders show similar tendencies in terms of particle size and tap density. Electrochemical characterization is performed after fabricating a coin cell using NCM as the cathode and Li metal as the anode. The NCM powders from the precursors obtained in air and those from the precursors obtained in nitrogen have similar initial charge/discharge capacities and cycle life. In conclusion, the powders co-precipitated in air can be utilized as precursor materials, replacing those synthesized in the presence of nitrogen injection, which is the usual industrial practice.
Citations
The electrochemical properties of cells assembled with the LiNiO2 (LNO) recycled from cathode materials of waste lithium secondary batteries (Li[Ni,Co,Mn]O2), were evaluated in this study. The leaching, neutralization and solvent extraction process were applied to produce high-purity NiSO4 solution from waste lithium secondary batteries. High-purity NiO powder was then fabricated by the heat-treatment and mixing of the NiSO4 solution and H2C2O4. Finally, LiNiO2 as a cathode material for lithium ion secondary batteries was synthesized by heat treatment and mixing of the NiO and Li2CO3 powders. We assembled the cells using the LiNiO2 powders and evaluated the electrochemical properties. Subsequently, we evaluated the recycling possibility of the cathode materials for waste lithium secondary battery using the processes applied in this work.