The relationship between failure mechanism of nickel-rich layered oxide for lithium batteries and the research progress of coping strategies: a review

Identifying surface degradation, mechanical failure, and thermal instability phenomena of high energy density Ni-rich NCM cathode materials for lithium-ion batteries: a review

“… 26 The spinel-phase LiMn 2 O 4 is the lowest cost, environmental friendliness, and naturally abundant materials, but it exhibits the problem of Mn 2+ ion dissolution, which causes the capacity fading and limits its development. 27 Olivine LiFePO 4 is another positive electrode material with low cost, excellent electrochemical properties, great thermal stability, and non-toxicity. 7 This positive electrode has low Li-ion diffusion, poor conductivity, and poor charge/discharge rate performance.…”

“… 29 LiNiO 2 has the same structure as LiCoO 2 and high energy density and low cost; however, at high temperature or high voltage, it exhibits poor structural stability and low cycle reversible, which limits its development. 27 The structure and potential profiles of the olivine, spinel, and different layered cathode materials during discharge are shown in ( Fig. 2a ).…”

“…Furthermore, Mn stabilizes the local structure to achieve steady cycling performance, although Mn remains electrochemically inert in the tetravalent state during the charge–discharge process. 27 Consequently, the intrinsic structure and performance of LiNi x Co y Mn z O 2 strongly depend on the compositional ratio of Ni, Co, and Mn. 19 …”

“… 38 For Ni-rich cathode materials, the nickel content in NCM-based materials exceeds Co and Mn content, which is above 50%. 27,28 The theoretical capacity of conventional cathode materials is 170 mA h g −1 for olivine LiFePO 4 , 140 mA h g −1 for spinel LiMn 2 O 4 , 140–160 mA h g −1 for layered LiCoO 2 and these materials are limited by their insufficient capacity, which cannot meet the increasing requirements for practical applications. 39 The main advantage of Ni-rich materials is their high discharge capacity (200–220 mA h g −1 ), which represents a large increase in energy density (∼800 W h kg −1 ) as compared to conventional LiCoO 2 (∼570 W h kg −1 ) and LiMn 2 O 4 spinel (∼440 W h kg −1 ) materials.…”

“…In addition, poor cycle life due to structural instability upon long-term cycling, particularly under high charge voltage (>4.3 V), 42 high defect concentration, and insufficient C-rate performance become more prominent. 27 Not only these, the sensitivity to ambient moisture, the formation of micro-cracks 15,16 and micro-strain 16,18 during cycling, and the thermal instability upon delithiation, which cause capacity fading of Ni-rich oxides have been revealed. Parasitic reactions, 43 cation mixing by leading to restructured surface regions, 44 active material dissolution, 45 and oxygen release 46 are the primary factors responsible for the cathode surface degradation mechanism.…”