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Nickel-rich layered oxides LiNi x Co y Mn1- x - y O2 (x ≥ 0.8) have been recognized as the preferred cathode materials to develop lithium-ion batteries with high energy density (>300 Wh kg-1). However, the poor cycling stability and rate capability stemming from intergranular cracks and sluggish kinetics hinder their commercialization. To address such issues, a multi-scale boron penetration strategy is designed and applied on the polycrystalline LiNi0.83Co0.11Mn0.06O2 particles that are pre-treated with pore construction. The lithium-ion conductive lithium borate in grain gaps functions as the grain binder that can bear the strain/stress from anisotropic contraction/expansion, and provides more pathways for lithium-ion diffusion. As a result, the intergranular cracks are ameliorated and the lithium-ion diffusion kinetics is improved. Moreover, the coating layer separates the sensitive cathode surface and electrolyte, helping to suppress the parasitic reactions and related gas evolution. In addition, the enhanced structural stability is acquired by strong B-O bonds with trace boron doping. As a result, the boron-modified sample with an optimized boron content of 0.5% (B5-NCM) exhibits a higher initial discharge capacity of 205.5 mAh g-1 at 0.1C (1C = 200 mA g-1) and improved capacity retention of 81.7% after 100 cycles at 1C. Furthermore, the rate performance is distinctly enhanced by high lithium-ion conductive LBO (175.6 mAh g-1 for B5-NCM and 154.6 mAh g-1 for B0-NCM at 5C).

Nickel-rich layered oxides LiNixCoyMn1-x-yO2 (x ≥ 0.8) have been recognized as the preferred cathode materials to develop lithium-ion batteries with high energy density (>300 Wh kg−1). However, the poor cycling stability and rate capability stemming from intergranular cracks and sluggish kinetics hinder their commercialization. To address such issues, a multi-scale boron penetration strategy is designed and applied on the polycrystalline LiNi0.83Co0.11Mn0.06O2 particles that are pre-treated with pore construction. The lithium-ion conductive lithium borate in grain gaps functions as the grain binder that can bear the strain/stress from anisotropic contraction/expansion, and provides more pathways for lithium-ion diffusion. As a result, the intergranular cracks are ameliorated and the lithium-ion diffusion kinetics is improved. Moreover, the coating layer separates the sensitive cathode surface and electrolyte, helping to suppress the parasitic reactions and related gas evolution. In addition, the enhanced structural stability is acquired by strong B-O bonds with trace boron doping. As a result, the boron-modified sample with an optimized boron content of 0.5% (B5-NCM) exhibits a higher initial discharge capacity of 205.5 mAh g−1 at 0.1C (1C = 200 mA g−1) and improved capacity retention of 81.7% after 100 cycles at 1C. Furthermore, the rate performance is distinctly enhanced by high lithium-ion conductive LBO (175.6 mAh g−1 for B5-NCM and 154.6 mAh g−1 for B0-NCM at 5C).

LiNiO 2 (LNO) is recognized as the most promising cathode material for next-generation lithium-ion batteries owing to its highest energy density and economic benefit in the layered oxide cathode materials systems. However, severe cation disordering, multiple phase transformations and poor lithium-ion diffusion kinetics, which result in rapid degradation of cycling stabilities and rate properties, hinder its further practical applications. Cobalt doping is an effective strategy to address such issues, but the influences of cobalt on LNO materials have not been figured out completely yet. Hence, a systematical investigation of cobalt doping for LiNiO 2 cathode materials prepared by spray pyrolysis is conducted. The addition of cobalt enhances the stabilities of layered structures and suppresses the cation disordering effectively. The multiple-phase transformations during cycling are also alleviated significantly. Furthermore, cobalt doping can decrease charge transfer resistances and improve lithium-ion diffusion kinetics, especially at high de-lithiation states. As a result, the electrochemical performances are improved comprehensively after cobalt doping. The LNO with optimal doping amount exhibits an improved capacity retention of 78.0% after 100 cycles as compared with 64.9% for pristine LNO, and an outstanding rate performance of 167.2 ​mA ​h ​g−1 with the current density of 5 ​C (1 ​C ​= ​200 ​mA ​g−1). • Spherical morphologies with dense shell-loose interior structures for precursors. • Co doping suppresses the cation disordering and phase transformations. • Co doping decreases charge transfer resistances and improves lithium-ion diffusion kinetics. • Electrochemical performances are significantly enhanced by Co doping. [ABSTRACT FROM AUTHOR]

Li-rich oxides are materials shows a high specific discharge capacity which is achieved through a special charging procedure called activation. Still, these materials have the following disadvantages: a short cycle life and a drop of average discharge voltage. This paper describes the synthesis of Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 (LMR) and its 5 at.%. K doping (LMRK) by the sol-gel method. A capacity of the produced materials equals to 232 mAh/g for LMR and 228 mAh/g for LMRK, respectively, under 0.1 С discharge current. The criterion of Li 2 MnO 3 phase complete activation was suggested following the results of studying charge/discharge curves and structural changes revealed with the use of in situ XRD method. This criterion has become a basis for determining the charge/discharge modes (current, voltage) required for Li 2 MnO 3 phase complete activation. It has been found out that elevated current increases the voltage at which complete activation occurs. K doping affects the material diffusion characteristics and results in an extra increase in voltage at which complete activation occurs. The obtained results can be used to study the activation of Li-rich cathodic materials and to select the optimum operation mode of lithium-ion batteries manufactured with the use of such materials. [ABSTRACT FROM AUTHOR]

Nickel-rich layered oxides LiNi x Co y Mn 1- x - y O 2 ( x  ≥ 0.8) have been recognized as the preferred cathode materials to develop lithium-ion batteries with high energy density (>300 Wh kg -1 ). However, the poor cycling stability and rate capability stemming from intergranular cracks and sluggish kinetics hinder their commercialization. To address such issues, a multi-scale boron penetration strategy is designed and applied on the polycrystalline LiNi 0.83 particles that are pre-treated with pore construction. The lithium-ion conductive lithium borate in grain gaps functions as the grain binder that can bear the strain/stress from anisotropic contraction/expansion, and provides more pathways for lithium-ion diffusion. As a result, the intergranular cracks are ameliorated and the lithium-ion diffusion kinetics is improved. Moreover, the coating layer separates the sensitive cathode surface and electrolyte, helping to suppress the parasitic reactions and related gas evolution. In addition, the enhanced structural stability is acquired by strong B-O bonds with trace boron doping. As a result, the boron-modified sample with an optimized boron content of 0.5% (B5-NCM) exhibits a higher initial discharge capacity of 205.5 mAh g 0.11 Mn 0.06 O 2 particles that are pre-treated with pore construction. The lithium-ion conductive lithium borate in grain gaps functions as the grain binder that can bear the strain/stress from anisotropic contraction/expansion, and provides more pathways for lithium-ion diffusion. As a result, the intergranular cracks are ameliorated and the lithium-ion diffusion kinetics is improved. Moreover, the coating layer separates the sensitive cathode surface and electrolyte, helping to suppress the parasitic reactions and related gas evolution. In addition, the enhanced structural stability is acquired by strong B-O bonds with trace boron doping. As a result, the boron-modified sample with an optimized boron content of 0.5% (B5-NCM) exhibits a higher initial discharge capacity of 205.5 mAh g -1 at 0.1C (1C = 200 mA g -1 ) and improved capacity retention of 81.7% after 100 cycles at 1C. Furthermore, the rate performance is distinctly enhanced by high lithium-ion conductive LBO (175.6 mAh g -1 for B5-NCM and 154.6 mAh g -1 for B0-NCM at 5C)., Competing Interests: The authors declare that they have no conflicts of interest in this work., (© 2022 The Authors. Publishing Services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.)

Ultrahigh Ni-rich layered oxides have been regarded as one of the most promising cathode candidates. However, cycling instability induced by interfacial reactions and irreversible H2-H3 lattice distortion is yet to be demonstrated by an effective strategy that could construct a stable grain interface and microstructure. Here, Ni-rich cathode LiNi 0.92 Co 0.05 Mn 0.03 O 2 is modified by B and Ti to realize the synchronous regulation of a microstructure and the oxygen framework robustness. Compared with the large equiaxed crystalline grains for the pristine cathode, highly elongated grains with a strong radially oriented crystallographic texture in which the (003) facet is maximized are produced for Ti and B-modified LiNi 0.92 Co 0.05 Mn 0.03 O 2 . With the suppressed H2-H3 phase transition and cation mixing provided by radially oriented grains and turned local crystal oxygen framework robustness during cycling, the co-modified cathode exhibits enhanced Li + diffusion kinetics and a capacity retention of 78.3% after 100 cycles, which outperformed the 38.5% for the pristine cathode. The improved cycling performance suggests the significance of the turned microstructure and local crystal structure in suppressing internal strain and crystal structure degradation. The synchronous realization of microstructure engineering and local crystal structure turning by optimal element combination would provide a heuristic solution for the construction of high perform Ni-rich cathodes.

Li-rich Mn-based layered cathode materials are subjected to unsatisfactory cycle stability, rate performance and voltage fading from the undesirable structure evolution during cycling despite its ultrahigh specific capacity. In this paper, Na-doped Li 1.15 Na 0.05 [Mn 0.54 Ni 0.13 Co 0.13 O 2 is prepared via introducing larger ionic radius Na ion into the lithium layer of the Li-rich layered cathode material via co-precipitation and high temperature soild-state reaction method. As prepared Na-doped cathode exhibits excellent electrochemical performances, including initial discharge capacity as high as 281 mAh g−1 at 0.1 C and good rate capacity with reversible discharge capacity of 142 mAh g−1 at 5 C. Furthermore, the Na ion substitution substantially suppresses the occurrence of Li+/Ni2+ mixing and phase transformation of layered Li-rich Mn-based oxide materials during continuous cycling, stabilizing the host layered structure. Higher capacity retention of 93.4% can be maintained on Na-doped cathode material after 100 cycles at 1 C rate compared with the undoped cathode (86.3%). Besides, the Na ion substitution also effectively reduces the internal charge transfer impedance and promotes the Li-ion diffusion kinetics, manifesting a promising cathode alternative for new-generation Li-ion battery benefiting from the outstanding performances and simple procedure. Image 1 • Na-doped Li 1.15 Na 0.05 [Mn 0.54 Ni 0.13 Co 0.13 O 2 is synthesized by a facile method. • Na ion substitution substantially suppresses the occurrence of Li+/Ni2+ mixing and structural phase transformation. • Improved discharge capacity, rate capacity and cycle durability could be achieved. • The modification mechanism of layered cathode material is clarified. [ABSTRACT FROM AUTHOR]