Resolving complex intralayer transition motifs in high-Ni-content layered cathode materials for lithium-ion batteries

Mitigating the High-Charge Detrimental Phase Transformation in LiNiO2 Using Doping Engineering

“…We compare the phase stability of the O3, O1, and O1-3 phases as a function of Li concentration and temperature and calculate the phase diagrams of pristine and doped LiNiO 2 . The inclusion of the O1-3 phase corresponds to recent experimental reports of discrete O3 and O1 domains in charged Ni-rich cathodes. , Combining our results with previously reported experimental studies, we recommend to introduce high-valence dopants with ionic radii similar to that of Ni 3+ into Ni-rich and Co-free cathodes. This approach could potentially stabilize both surface and bulk structures of the cathode material.…”

“…Recently, Park et al reported that the O3-to-O1 phase transition in LiNiO 2 is more severe in the surface region of the cathode than in the bulk region, due to a higher concentration of oxygen vacancies near the surface. Wang et al − also demonstrated that the O1 phase is more vulnerable to oxygen loss as compared to the O3 phase. The oxygen loss lowers the energy barrier of Ni migration into the Li layer, thereby facilitating a transformation from the layered structure into a densified rocksalt structure and compromising reversibility of the O3-to-O1 transition.…”

“…Both these factors contribute to a strain-induced structural instability of the cathode, which typically manifests in the formation of microcracks . Recent studies also showed that the O1 phase could act as a nucleation site to (1) initialize cracking from the cathode particle surface and (2) provide diffusion pathways for oxygen loss, thereby promoting the irreversible transformation from the layered structure into a densified rocksalt structure. , Therefore, to develop the next-generation Ni-rich layered cathodes, it is critical to suppress the O1 phase formation. While the structural instability can be avoided by simply limiting the upper cutoff voltage to 4.1 V, this remedy comes at the cost of a decreased specific capacity .…”

“…The O1-3 phase exhibits O1 oxygen stacking which has been reported to promote cracking and oxygen loss. 9,10 Therefore, the formation of O1 oxygen stacking indicates an emergent structural instability at x > 0.75, likely contributing to structural damage and deteriorated cycling stability. 4 This is in excellent agreement with experimental observations, which reported that the maximum rechargeable capacity is 200 mAh/ g with x = 0.75 in Li 1−x NiO 2 .…”

Cobalt/aluminum co-substitution in a LiNi0.9Mn0.1O2layered cathode for improving kinetics

“…Currently, the climate goals of the Paris Agreement are driving the rapid growth of the lithium-ion battery (LIB) market, especially in electric vehicles (EVs) and large-scale energy storage systems. [1][2][3][4] Such applications require LIBs with high energy density, long service life, and fine rate capacities. Ni-rich layered LiNi x Co y Mn 1ÀxÀy O 2 (NCM) materials have been considered an ideal cathode for EVs owing to their high theoretical capacity (270 mA h g À1 ).…”