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Ni-rich layered cathode materials for lithium-ion batteries have received widespread attention due to their large capacity and low cost; however, the structural stability of the material needs to be improved. Herein, F-doped and undoped cathode materials prepared with an advanced co-precipitation method were used to measure the effect of F doping on the material. Compared to the undoped sample, the F-doped cathode materials exhibited an improved rate performance, because the porous structure of F-doped cathode materials is favorable for the infiltration of the electrolyte and the material, and the F-doped cathode material has a larger (003) crystal plane and a smaller Li+ migration barrier energy. This simple F-doping treatment strategy provides a promising way to improve the performance of Ni-rich layered cathode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

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]

Carbon spheres, prepared by hydrothermally treating fresh potato starch, is employed as the sulfur host to configure a high-performance cathode substrate candidate for Li–S batteries. As confirmed by experimental results, both the improved the rate and cycle performances of Li–S batteries cathode with gradient sulfur immobilization, are mainly attributed to the confining, adsorption and conduction multi-functions of as-prepared carbon spheres toward polysulfides. Specifically, on starting the discharging/charging cycles, the active material α-S 8 is irreversibly converted to polysulfides and then transformed between β-S 8 and polysulfides during the next charge/discharge cycles. After initialization at 0.1C for 3 cycles, the initial reversible discharge capacities of the Li–S batteries cathode with optimized sulfur amount are 1072.5, 831.3, 780.4, 726.8, 714.3, 702.7 mAh g−1 sulfur at 0.1, 0.5, 1, 2, 3 and 4 C, which is superior to those of the most previously reported reports. Besides that, as-designed potato-derived carbon based composite cathodes exhibits remarkable rate performance and cycling stability even at wide temperature ranging from −40 to 60 °C, which evidently supports the dominant role of as-prepared 3D carbon spheres in boosting the cathode performance for Li–S batteries. [ABSTRACT FROM AUTHOR]

In this study, Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 cathode materials for lithium-ion battery have been successfully synthesized by triethanolamine(TEA) and ethylene glycol solution assisted co-precipitation technology and solid-state sintering method. Relevant tests (XRD, ICP, SEM) were used to determine the structure, composition and morphology of the Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 cathode materials. The electrochemical tests were performed to evaluate the electrochemical performance of the materials. The results show that the initial discharge capacity is 263.8 mAh g −1 at 0.1C rate in a half battery. Furthermore, this cathode material retains a final capacity of 186 mAh g −1 at 0.5C after 200 cycles and displays an outstanding capacity retention of 98.5%. And all tests prove that the Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 lithium-rich materials synthesized with TEA and ethylene glycol solution assisted co-precipitation method have excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

Schematic illustration of growth mechanism of spherical particles for precursors. [Display omitted] • The crystal growth for precursors is investigated by modeling and experiment. • The key mechanism for the formation of hierarchical precursor particles is revealed. • The cathode with discharge capacity over 190 mAh g−1 at 1C is successfully prepared. Hierarchical structure Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 agglomerates were formed by coprecipitation method in the presence of aqueous ammonia in a continuous stirred tank reactor (CSTR). The resultant spherical secondary particles are comprised of highly anisotropic primary grains as building blocks, which retain a distinct hexagonal flake morphology with six {0 1 0} equivalent crystal facets and two other {0 0 1} facets. The formation of hierarchical agglomerates typically undergoes three steps: (i) the formation of grain nuclei (homogeneous nucleation), (ii) anisotropic growth of grains and formation of hexagonal nanosheets, (iii) agglomeration of single crystal grains and formation and growth of spherical agglomerates. This unique hierarchical structures of Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 point to its promising applications in preparation of high-performance cathode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

This study synthesizes pristine and Nb-doped lithium-rich manganese-based cathode materials by solvothermal and high-temperature solid-phase methods. Analysis by focused ion beam scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy indicates successful Nb doping into the material's bulk structure. Electrochemical evaluation reveals that electrochemical performance is significantly enhanced by Nb doping. The discharge capacity of Nb-0.02 can maintain 271.7 mAh·g−1, and its cycle retention rate is up to 98.50% after 300 cycles at 0.2C; however, under the same parameters, the pristine material's discharge capacity and cycle retention rate are 212.8 mAh·g−1 and 86.68%. The initial coulombic efficiency and initial discharge capacity of Nb-0.02 is 86.94% and 287.5 mAh·g−1, while that of the pristine material is 73.59% and 234.2 mAh·g−1. Density functional theory calculations demonstrate that Nb doping accelerates Li-ion diffusion and stabilizes material structure due to stronger Nb–O bonds from reduced Li-ion migration barrier energy. Thus, the proposed modification strategy for Nb doping can illuminate the structural design of lithium-rich manganese-based cathode materials. • Nb elements are distributed across the surface and in the bulk material. • ICE and cycle performance are significantly enhanced by Nb doping. • DFT calculations confirm that Nb doping accelerates Li-ion diffusion. [ABSTRACT FROM AUTHOR]