چكيده به لاتين
The widespread commercialization of cobalt-free nickel-rich layered cathodes in advanced lithium-ion batteries (LIBs) has been severely hindered by their poor structural ordering and electrochemical performance. To address these limitations, researchers have employed various strategies, including doping, surface modification, synthesis temperature optimization, element substitution, and composite electrodes. Numerous single dopants, such as Al, Ti, Zr, Mg, Mo, Nb [1], and Sn [2], have been investigated to enhance the electrochemical performance of these materials. Vanadium has also gained attention as a dopant due to its unique properties: (1) multiple oxidation states that can increase the lithium-ion diffusion coefficient and (2) a large atomic radius that facilitates strong oxygen bonding in the structure, enhancing crystal stability. These characteristics are expected to significantly improve capacity, Coulombic efficiency, cyclability, and rate capability. In this study, LiNi0.9Mn0.5Al0.5 was synthesized as the base cathode material and then doped with V5+. XRD results revealed significant peak shifts following doping, confirming the incorporation of V5+ into the structure. This doping also effectively prevented Ni2+/Li+ mixing, leading to improved lithium-ion transport. Moreover, the co-operative movement of transition metal (TM) layers during deep discharge was effectively suppressed due to the V5+ linkage in the TM layer. This resulted in a significant reduction in the H2-H3 phase transition as observed by CV measurements, enabling the suppression of kinetic barriers at high voltages (above 4.2 V) and eliminating particle cracking during extended cycling. Consequently, the designed NMA-V cathode exhibited a Coulombic efficiency of 94.21% after 50 cycles. This work provides a promising strategy for designing high-performance, low-cost, cobalt-free, nickel-rich cathodes for next-generation advanced LIBs.
