Local structure adaptability through multi cations for oxygen redox accommodation in Li-Rich layered oxides

Abstract

Stable lattice oxygen redox (l-OR) is the key enabler for achieving attainable high energy density in Li-rich layered oxide cathode materials for Li-ion batteries. However, the unique local structure response to oxygen redox in these materials, resulting in energy inefficiency and hysteresis, still remains elusive, preventing their potential applications. By combining the state-of-the-art neutron pair distribution function with crystal orbital overlap analysis, we directly observe the distinct local structure adaption originated from the potential O-O chemical bonds. The structure adaptability is optimized based on the nature of multi transition metals in our model compound Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 , which accommodates the oxygen redox and at the same time preserves the global layered structure. These findings not only advance the understanding of l-OR, but also provide new perspectives in the rational design of high-energy-density cathode materials with reversible and stable l-OR.

A perspective on sustainable energy materials for lithium batteries

“…3. Lithium-and manganese-rich cathodes: Lithiumand manganese-rich layer-structured cathodes with reduced Co content (such as Li 43,44 However, the high capacity is at the cost of severe phase transitions and oxygen release, limiting the cathode voltage caused by activating the lower-voltage redox couples of Mn 3+ /Mn 4+ and Co 2+ /Co 3+ besides the pristine Ni 2+ /Ni 3+ , Ni 3+ /Ni 4+ , and O 2− /O − redox couples. 45,46 Surface coating and introducing foreign elements can be efficient in inhibiting the voltage fade.…”

“…Compared with LCO and NMC, the theoretical capacity of LFP is relatively low (170 mAh/g at room temperature), which limits the practical application of LFP, especially in EVs 40 . By size reduction and carbon coating 41 to improve the rate performance 42 and technology improvement in the pack design, such as cell to pack (CTP) strategy by CATL Corporation and Blade Battery strategy by BYD Corporation, the energy and power density can be largely increased to satisfy the demand of EVs. Lithium‐ and manganese‐rich cathodes: Lithium‐ and manganese‐rich layer‐structured cathodes with reduced Co content (such as Li 1.2 Ni 0.15 Co 0.1 Mn 0.55 O 2 , Co content: 6.9 vs. 60.2 wt.% for LCO) can deliver high reversible capacities of over 280 mAh/g, which is nearly double of those of LCO and LFP cathodes 43,44 . However, the high capacity is at the cost of severe phase transitions and oxygen release, limiting the cathode voltage caused by activating the lower‐voltage redox couples of Mn 3+ /Mn 4+ and Co 2+ /Co 3+ besides the pristine Ni 2+ /Ni 3+ , Ni 3+ /Ni 4+ , and O 2− /O − redox couples 45,46 .…”

Quantifying redox heterogeneity in single-crystalline LiCoO2 cathode particles

“…In deeply delithiated states, the lattice distortion (Singer et al, 2018;Wang et al, 2018; could be severe and the anion redox (Zhang et al, 2019;Gent et al, 2017;Dai et al, 2019;Li, Lee et al, 2019;Xu, Sun et al, 2018) could be activated. Such phenomena could be nucleation points for the accumulation of the mechanical strain that is eventually released through mesoscale particle cracking (Zhao et al, 2019;Yan et al, 2017;Tsai et al, 2019;Markevich et al, 2019). The formation of morphological defects (e.g.…”

LiVOPO4‐Modified Lithium‐Rich Layered Composite Cathodes for High‐Performance Lithium‐Ion Batteries

“…Lithium‐ion batteries have received considerable attention in portable electronics, smart grid, and electric vehicles (EVs) [1–4] . However, conventional cathodes used in LIBs (for example, LiFePO 4 , LiMn 2 O 4 , and LiCoO 2 ) have limited capacities of less than 200 mAh g –1 , which cannot meet the requirements for high energy/power density LIBs [5] .…”