윤종승 교수

Ni-rich Li[Ni x Co y Mn 1– x – y ]O 2 cathodes ( x = 0.6, 0.8, 0.9, and 0.95) were tested to characterize the capacity fading mechanism of extremely rich Ni compositions. Increasing the Ni fraction in the cathode delivered a higher discharge capacity (192.9 mA h g –1 for Li[Ni 0.6 Co 0.2 Mn 0.2 ]O 2 versus 235.0 mA h g –1 for Li[Ni 0.95 Co 0.025 Mn 0.025 ]O 2 ); however, the cycling stability was substantially reduced. Li[Ni 0.6 Co 0.2 Mn 0.2 ]O 2 and Li[Ni 0.8 Co 0.1 Mn 0.1 ]O 2 retained more t

A Li[Li(0.19)Ni(0.16)Co(0.08)Mn(0.57)]O(2) cathode was coated with AlF(3) on the surface. The AlF(3)-coating enhanced the overall electrochemical characteristics of the electrode while overcoming the typical shortcomings of lithium-enriched cathodes. This improvement was attributed to the transformation of the initial electrode layer to a spinel phase, induced by the Li chemical leaching effect of the AlF(3) coating layer.

A series of single-crystal, Ni-rich Li[NixCoyMn1–x–y]O2 (NCM) cathodes (x = 0.7, 0.8, and 0.9) with particle diameters of ∼3 μm are systematically compared with polycrystalline cathodes with corresponding Ni contents. Despite their high resistance to microcracking, the electrochemical performances of single-crystal NCM cathodes, in terms of capacity and cycling stability, are inferior to those of polycrystalline NCM cathodes. In situ XRD and TEM analyses reveal that the lithium concentrations in

Abstract Boron‐doped Li[Ni 0.90 Co 0.05 Mn 0.05 ]O 2 cathodes are synthesized by adding B 2 O 3 during the lithiation of the hydroxide precursor. Density functional theory confirms that boron doping at a level as low as 1 mol% alters the surface energies to produce a highly textured microstructure that can partially relieve the intrinsic internal strain generated during the deep charging of Li[Ni 0.90 Co 0.05 Mn 0.05 ]O 2 . The 1 mol% B‐Li[Ni 0.90 Co 0.05 Mn 0.05 ]O 2 cathode thus delivers a dis

Ni-rich Li[Ni1–x–yCoxAly]O2 (NCA) cathodes (1 – x – y = 0.8, 0.88, and 0.95) are synthesized to investigate the capacity fading mechanism of Ni-rich NCA cathodes. The capacity retention and thermal property of the cathodes deteriorate as their discharge capacity increases when the Ni fraction is increased. The capacity fading correlates well with the anisotropic volume variations caused by the H2–H3 phase transition and the resulting extent of microcracking. Although all three cathodes start to

W-doping produced the two-phase (<italic>Fm</italic>3̄<italic>m</italic> and <italic>R</italic>3̄<italic>m</italic>) structure which improved the cycling and thermal stability of the Ni-rich layered cathodes.

A spherical stoichiometric LiNiO 2 particle, which was composed of compactly packed nanosized primary particles, was prepared and cycled at different cutoff voltages to explicitly demonstrate the effect of phase transitions during Li deintercalation/intercalation on the Li-ion intercalation stability of LiNiO 2 . The capacity retention was greatly improved by suppressing the H2 → H3 phase transition at 4.1 V, such that 95% of the initial capacity (164 mAh g –1 ) was retained after 100 cycles whe

A series of Ni-enriched Li[NixCoyAlz]O2 cathodes (x = 0.80–0.95) were synthesized and evaluated comprehensively to investigate the capacity fading mechanism. Capacity retention was shown to be strongly related to the extent of microcracking within the secondary particles. Moreover, the range and limit of the depth of discharge (DOD), which determined the extent of microcracking, critically affected the cycling stability such that the extremely Ni-rich Li[Ni0.95Co0.04Al0.01]O2 cathode cycled at a

Li[Ni1–x–yCoxAly]O2 (NCA) and Li[Ni1–x–yCoxMny]O2 (NCM) cathodes have been the archetypes of current high-energy-density cathodes for Li-ion batteries. A hybrid of NCA and NCM cathodes, a quaternary system consisting of Li[Ni0.89Co0.05Mn0.05Al0.01]O2 (NCMA) was benchmarked against NCM and NCA with similar Ni contents. The quaternary NCMA cathode delivered a capacity of 228 mAh g–1 and outperformed the benchmarking cathodes in long-term cycling stability (85% after 1000 cycles). The reduction in

This perspective discusses the challenges to, and strategies for, the commercially viable development of these three classes of cathodes for LIBs.

Abstract A multicompositional particulate Li[Ni 0.9 Co 0.05 Mn 0.05 ]O 2 cathode in which Li[Ni 0.94 Co 0.038 Mn 0.022 ]O 2 at the particle center is encapsulated by a 1.5 µm thick concentration gradient (CG) shell with the outermost surface composition Li[Ni 0.841 Co 0.077 Mn 0.082 ]O 2 is synthesized using a differential coprecipitation process. The microscale compositional partitioning at the particle level combined with the radial texturing of the refined primary particles in the CG shell la

Abstract Li[Ni 0.9 Co 0.1 ]O 2 (NC90), Li[Ni 0.9 Co 0.05 Mn 0.05 ]O 2 (NCM90), and Li[Ni 0.9 Mn 0.1 ]O 2 (NM90) cathodes are synthesized for the development of a Co‐free high‐energy‐density cathode. NM90 maintains better cycling stability than the two Co‐containing cathodes, particularly under harsh cycling conditions (a discharge capacity of 236 mAh g −1 with a capacity retention of 88% when cycled at 4.4 V under 30 °C and 93% retention when cycled at 4.3 V under 60 °C after 100 cycles). The re