Understanding the role of Mg-doped on core-shell structured layered oxide LiNi0.6Co0.2Mn0.2O2

Flexible and Scalable Magnesium Replenishment in NCM Cathode Enabled by Mobile Mg2+ Enriched MgV2O4

A small amount of Mg2+ doping can show a significant effect on the surface protection and structural stability of the nickel-rich layered oxide cathode, but the traditional doping process involves completely changing the initial raw material proportions with subsequent trial and error adjustments. Herein, a concept of Mg2+ release film is proposed, in which Mg2+ can easily permeate into various layered oxide cathodes during cycling. Meanwhile, to realize this concept, MgV2O4 with mobile Mg2+ in the structures and then fabricated a self-supporting MgV2O4 membrane are synthesized. As a protective layer for cathode, the MgV2O4 membrane release Mg2+ in situ during the electrochemical process, providing structural reinforcement to the cathode surface as a "pillar" within the lattice. Thanks to the MgV2O4 membrane, the cycle life of LiNio.8Co0.1Mn0.1O2(NCM811) coupled with the MgV2O4 interlayer at 1.0 C is increased by 1.9 times compared to bare NCM811. Furthermore, this novel Mg2+ releasing film demonstrates excellent versatility, enabling other nickel-based layered oxide to achieve a high-capacity retention of 86.4% after 800 cycles at 1.0 C. This approach provides scalable cathode protection and repair strategies for commercially viable batteries.

Comprehensive Study of Ti and Ta Co-Doping in Ni-Rich Cathode Material LiNi0.8Mn0.1Co0.1O2 Towards Improving the Electrochemical Performance

Layered Ni-rich oxides (LiNi1-x-yCoxMnyO2) cathode materials are of current interest in high-energy-demanding applications, such as electric vehicles because of high discharge capacity and high intercalation potential. Here, the effect of co-doping a small amount of Ti and Ta on the crystal structure, morphology, and electrochemical properties of high Ni-rich cathode material LiNi0.8Mn0.1Co0.1-x-yTixTayO2 (0.0≤x+y≤0.2) was systematically investigated. This work demonstrates that an optimum level of Ti and Ta doping is beneficial towards enhancing electrochemical performance. The optimal Ti4+ and Ta5+ co-doped cathode LiNi0.8Mn0.1Co0.09Ti0.005Ta0.005O2 exhibits a superior initial discharge capacity of 161.1 mAh g-1 at 1 C, and excellent capacity retention of 87.1 % after 250 cycles, compared to the pristine sample that exhibits only 59.8 % capacity retention. Moreover, the lithium-ion diffusion coefficients for the co-doped cathode after the 3rd and 50th cycles are 9.9×10-10 cm2 s-1 and 9.3×10-10 cm2 s-1 respectively, which is higher than that of the pristine cathode (3.3×10-10 cm2 s-1 and 2.5×10-10 cm2 s-1 respectively). Based on these studies, we conclude that Ti and Ta co-doping enhances structural stability by mitigating irreversible phase transformation, improving Li-ion kinetics by expanding interlayer spacing, and nanosizing primary particles, thereby stabilizing high-nickel cathode materials and significantly enhancing cyclability.

Preparation and electrochemical investigation of single-crystal LiNi0.6Co0.2Mn0.2O2 for high-performance lithium-ion batteries

Ni-rich layered cathode materials have large reversible capacity.

Nickel-Rich Layered Cathode Materials for Lithium-Ion Batteries

Nickel-rich layered transition metal oxides are considered as promising cathode candidates to construct next-generation lithium-ion batteries to satisfy the demands of electrical vehicles, because of the high energy density, low cost, and environment friendliness. However, some problems related to rate capability, structure stability, and safety still hamper their commercial application. In this Review, beginning with the relationships between the physicochemical properties and electrochemical performance, the underlying mechanisms of the capacity/voltage fade and the unstable structure of Ni-rich cathodes are deeply analyzed. Furthermore, the recent research progress of Ni-rich oxide cathode materials through element doping, surface modification, and structure tuning are summarized. Finally, this review concludes by discussing new insights to expand the field of Ni-rich oxides and promote practical applications.

Enhanced Cathode Performance: Mixed Al2O3 and LiAlO2 Coating of Li1.2Ni0.13Co0.13Mn0.54O2

Li-rich, manganese-based cathode materials are attractive candidates for Li-ion batteries because of their excellent capacity, but poor rate and cycle performance have limited their commercial applications. Herein, Li-rich, manganese-based cathode materials were modified with aluminum isopropoxide as an aluminum source modifier using a sol-gel technique followed by a wet chemical method. To investigate the structure, morphology, electronic state, and elemental composition of both pristine- and surface-modified Li_1.2Ni_0.13Co_0.13Mn_0.54O₂, various characterizations were performed. Based on density functional theory simulations and the results of electrochemical tests, the surface of the modified cathode material was found to contain at least part of the LiAlO₂ phase. This was attributed to the aluminum isopropoxide reacting with a Li₂CO₃/LiOH byproduct on the material surface to form LiAlO₂ with a three-dimensional Li-ion channel structure. Electrochemical testing revealed that a 3 wt % aluminum isopropoxide coating of cathode materials exhibited excellent electrochemical performance. Furthermore, the initial Coulombic efficiency and discharge capacity at 0.1 C were up to 88.55% and 272.7 mAh g^-1, respectively. A final discharge capacity of 186.4 mAh g^-1 was achieved, corresponding to a capacity retention of 83.55% after 300 cycles at 0.5 C. This was attributed to LiAlO₂ partially accelerating the diffusion of Li ions and Al₂O₃ aiding the avoidance of side reactions in the mixed coating layer by partially protecting the structure.