A Review of Degradation Mechanisms and Recent Achievements for Ni‐Rich Cathode‐Based Li‐Ion Batteries

Abstract

The growing demand for sustainable energy storage devices requires rechargeable lithium‐ion batteries (LIBs) with higher specific capacity and stricter safety standards. Ni‐rich layered transition metal oxides outperform other cathode materials and have attracted much attention in both academia and industry. Lithium‐ion batteries composed of Ni‐rich layered cathodes and graphite anodes (or Li‐metal anodes) are suitable to meet the energy requirements of the next generation of rechargeable batteries. However, the instability of Ni‐rich cathodes poses serious challenges to large‐scale commercialization. This paper reviews various degradation processes occurring at the cathode, anode, and electrolyte in Ni‐rich cathode‐based LIBs. It highlights the recent achievements in developing new stabilization strategies for the various battery components in future Ni‐rich cathode‐based LIBs.

Technological innovation vs. tightening raw material markets: falling battery costs put at risk

“…6 However, higher nickel contents are associated with challenges regarding battery safety (thermal runaway under abuse conditions) and performance (mainly capacity and voltage decay, impedance growth). 21,[23][24][25] The risk of thermal runaway can primarily be attributed to oxygen evolution and subsequent reactions with electrolyte and lithiated anode, which is a result of the thermodynamic instability of nickel-rich layered oxides at large lithium utilization or high temperature. [23][24][25] Performance degradation has a variety of origins, including residual lithium compounds, Ni 2+ /Li + cationic disorder, oxygen evolution and accompanying phase transition, transition metal ion dissolution and crack formation.…”

“…21,[23][24][25] The risk of thermal runaway can primarily be attributed to oxygen evolution and subsequent reactions with electrolyte and lithiated anode, which is a result of the thermodynamic instability of nickel-rich layered oxides at large lithium utilization or high temperature. [23][24][25] Performance degradation has a variety of origins, including residual lithium compounds, Ni 2+ /Li + cationic disorder, oxygen evolution and accompanying phase transition, transition metal ion dissolution and crack formation. 21,23,25 To mitigate these challenges, development efforts focus on various approaches, including the optimization of synthesis methods, foreign-ion doping, surface coatings, single-crystal, core-shell and concentration gradient particle structures, and the application of non-flammable and oxygenscavenging electrolytes.…”

“…[23][24][25] Performance degradation has a variety of origins, including residual lithium compounds, Ni 2+ /Li + cationic disorder, oxygen evolution and accompanying phase transition, transition metal ion dissolution and crack formation. 21,23,25 To mitigate these challenges, development efforts focus on various approaches, including the optimization of synthesis methods, foreign-ion doping, surface coatings, single-crystal, core-shell and concentration gradient particle structures, and the application of non-flammable and oxygenscavenging electrolytes. 21,[23][24][25] Based on harmonized industry expectations, a gradual material development from NMC622 in 2020 to NMC955 in 2030 is assumed in this study.…”

“…21,23,25 To mitigate these challenges, development efforts focus on various approaches, including the optimization of synthesis methods, foreign-ion doping, surface coatings, single-crystal, core-shell and concentration gradient particle structures, and the application of non-flammable and oxygenscavenging electrolytes. 21,[23][24][25] Based on harmonized industry expectations, a gradual material development from NMC622 in 2020 to NMC955 in 2030 is assumed in this study. The respective materials exhibit distinct properties such as specific discharge capacity, average discharge potential vs. lithium, and price, being major drivers of cell energy and cost.…”

Surface Reconstruction of Ni‐Rich Layered Cathodes: In Situ Doping versus Ex Situ Doping

“…As a solution, manipulating the synthesis procedure can effectively balance the favorable lithiation process and unfavorable Ni 2+ migration, optimizing the cationic order in the final layered structure. [ 22 ] Therefore, a more precise and effective method called in situ doping, that is, doping heteroatoms onto the Ni x Co y Mn 1− x − y (OH) 2 (NCM(OH) 2 ), was adopted, which can promote the diffusion of heteroatoms and realize a deeper and more uniform heteroatoms doping compared to ex situ doping, that is, doping heteroatoms onto the NCM. Unfortunately, few papers focused on obvious difference between in situ doping and ex situ doping for improving battery performance of NCM cathodes.…”