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Nickel-rich ternary material LiNi0.8Co0.1Mn0.1O2 is the promising cathode for lithium ion battery, but it has the disadvantage of structural instability. The common method for modifying its electrochemical performance is element doping, such as sodium, aluminum, magnesium and other elements, because the elements with different types and valences have varied ionic radii and binding energies to oxygen. They are incorporated into the layered nickel-rich ternary material to play the distinct roles. In this work, we investigate the effect of Na and Mg co-doping on Li(Ni0.8Co0.1Mn0.1)O2. Our results suggest that the mixed doping has no effect on the crystal structure and morphology of the material. The Rietveld refinement results demonstrated that cation mixing reduced. The electrochemical test results show that the proper amount of Na and Mg mixed doping improves the cyclic reversibility and reduces the resistance of the material. Na and Mg elements can promote each other to improve the electrochemical performance of the material. At the same time we note that high doping concentrations might mitigate the Li diffusion rates. [ABSTRACT FROM AUTHOR]

Layered high-nickel LiNi 0.8 Co 0.1 Mn 0.1 O 2 is a promising candidate of the next generation cathode materials for lithium-ion batteries. However, severe cycling instability and fast capacity drop induced by anisotropic structured change restrict its wide application. To address these defects, the structure design of cathodes is conducted. Herein, a hierarchical layered LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode consisting of orderly stacking hexagonal nanosheets with exposed active {104} facets is successfully synthesized by an improved co-precipitation process and followed with a high temperature lithiation reaction. Benefiting from this unique texture, exposed active {104} facets with lower surface energy supply 3D barrier-free Li+ ion diffusion channels, significantly improving the efficiency of the Li+ diffusion. Moreover, the consistent arrangement of nanosheets in the manner of the {001} facets close attachment is beneficial to alleviate the stress caused by the anisotropic structured change. Thus, this cathode material presents both superior reversible capability (203.8 mAh g−1 at 0.1C, 184.5 mAh g−1 at 1 C, 173.0 mAh g−1 at 5 C and 161.3 mAh g−1 at 10 C) and stable cycling performance (capacity retention of 89.3% after 100 cycles at 1 C, 55.3% after 300 cycles at 5 C and 59.6% after 300 cycles at 10 C). Schematic of single crystal shape evolution of the cathode materials and the corresponding cycle performance of the NCM-3 sample at different rates. [Display omitted] • A hierarchical cathode material consisting of orderly stacking nanosheets with exposed active {104} facets was successfully synthesized. • The exposed active {104} facets with lower surface energy could supply barrier-free Li+ ion diffusion channels. • The consistent arrangement of nanosheets is beneficial to alleviate the stress and inhibit the pulverization of secondary particles. • The hierarchical cathode material presents both superior reversible capability and stable cycling performance. [ABSTRACT FROM AUTHOR]

Lithium-rich manganese-based oxides are included in high-capacity cathodes. Herein we introduce a certain amount of Mg and Na into lithium-rich manganese-based oxide microspheres to overcome the weak cycling performance and poor rate capacity. This work uses the hydrothermal method combined with the high-temperature solid-phase method and CH 3 COONa and C 4 H 14 MgO 8 as dopants. Transmission electron microscopy (TEM), X-ray diffraction (XRD), focused ion beam scanning electron microscopy (FIB-SEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and electrochemical characterization are performed to systematically assess the effect of Na and Mg element doping on the morphology, structure and electrochemical characteristics of Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2. The results show that the material has excellent electrochemical performance. These improvements could be related to the presence of Na in Li layers and Mg in TM layers, which can speed up Li-ion diffusion kinetics and improve ionic and electronic conductivity. DFT calculations demonstrate that the injection of Na and Mg reduces the lithium-ion migration barrier energy. This dual-doped modification technique may help researchers better understand how to build high-capacity and stable cathode materials for LIBs. [ABSTRACT FROM AUTHOR]

Solid-phase reactions were used for the synthetization of the spinel Li 1.6 Mn 1.6 O 4 powder and the lithium ion-sieve MnO 2 ·0.5H 2 O was subsequently obtained by the leaching of the lithium. The physical characterization showed that the polycrystalline precursor and the MnO 2 ·0.5H 2 O were nearly pure spinel, as well as that during the process of the adsorption-desorption, the structural stability was high. The Langmuir isotherm and pseudo second-order kinetics model showed consistency with the adsorption behavior, which indicated the presence of homogeneous adsorption sites for the lithium adsorption and that its process was chemisorption. Adsorbents were found to remain being characterized with a relatively high Li+ uptake (26.13 ​mg ​g−1) with low manganese extracted (1.71%) after the circulation experiment was performed up to 5 times, proving a significant repeatability and stability for the lithium ion-sieve. The concentration factors exhibited the highly selective adsorption capacity for absorbent from Qarhan raw brine with high concentrations of Na+, K+, Ca2+, Mg2+. The adsorbents could be efficiently used for Li+ recovery from Salt Lake brine as well as its excellent potential for further application. Due to the sieving effect (steric hindrance effect and hydration free energy effect), the lithium ion-sieve selectively adsorbed Li+ when the ion-sieve was immersed in brine, indicating that the ion-sieve MnO 2 ·0.5H 2 O was expected to recover Li+ from the solutions including Salt Lake brine, seawater, and wastewater. Image 1 • The precursor was prepared by practical two-stage solid-phase sintering technique. • The Li 1.6 Mn 1.6 O 4 exhibited excellent adsorption performance. • The materials showed the highly selective adsorption from Qarhan raw brine. [ABSTRACT FROM AUTHOR]