High-Voltage Cycling Induced Thermal Vulnerability in LiCoO₂ Cathode: Cation Loss and Oxygen Release Driven by Oxygen Vacancy Migration

Abstract

The release of the lattice oxygen due to the thermal degradation of layered lithium transition metal oxides is one of the major safety concerns in Li-ion batteries. The oxygen release is generally attributed to the phase transitions from the layered structure to spinel and rocksalt structures that contain less lattice oxygen. Here, a different degradation pathway in LiCoO2 is found, through oxygen vacancy facilitated cation migration and reduction. This process leaves undercoordinated oxygen that gives rise to oxygen release while the structure integrity of the defect-free region is mostly preserved. This oxygen release mechanism can be called surface degradation due to the kinetic control of the cation migration but has a slow surface to bulk propagation with continuous loss of the surface cation ions. It is also strongly correlated with the high-voltage cycling defects that end up with a significant local oxygen release at low temperatures. This work unveils the thermal vulnerability of high-voltage Li-ion batteries and the critical role of the surface fraction as a general mitigating approach.

Reversible (De)Intercalation of Hydrated Zn2+ in Mg2+‐Stabilized V2O5 Nanobelts with High Areal Capacity

“…[ 2,3 ] In addition, there also arises safety concerns over combustible organic electrolyte. [ 4 ] In this way, the aqueous rechargeable battery with advantages, including low cost, high operation safety, and environmental friendliness, becomes a very promising electrochemical energy storage device. [ 5 ] Moreover, the ionic conductivity in the aqueous electrolyte is higher by several orders of magnitude than that in the organic electrolyte.…”

Advanced Electron Energy Loss Spectroscopy for Battery Studies

“…For instance, Sun et al used the in situ EELS and TEM imaging to evaluate the oxygen release during heating the Li x CoO 2 cathode after the high-voltage (4.6 V) cycling (Figure 9d). [90] From the EELS line scan, the O/Co ratio at the surface was lower than that in the bulk, suggesting the continuous oxygen loss near the surface region. Furthermore, they found that such thermal degradation was proceeded through the oxygen vacancies and facilitated by the cation migration and reduction.…”

Potassium‐Ion Activating Formation of Fe−N−C Moiety as Efficient Oxygen Electrocatalyst for Zn‐Air Batteries

“…[1] However, a prompt increase in the energy demand because of industrialization and motorization and the associated environmental problems lead to the requisite for replacing traditional fuels with sustainable clean energy sources. [2][3][4][5][6][7][8][9][10] In this regard, the best alternatives are fuel cells and metal air batteries having zero emission and high energy conversion rate. [11][12][13][14] Among them, the oxygen reduction reaction (ORR) at cathode is of utmost importance due to the sluggish kinetics, limiting their practical applications.…”

“…Presently, about 78 % of the global energy requirement is accomplished by using fossil fuels [1] . However, a prompt increase in the energy demand because of industrialization and motorization and the associated environmental problems lead to the requisite for replacing traditional fuels with sustainable clean energy sources [2–10] . In this regard, the best alternatives are fuel cells and metal air batteries having zero emission and high energy conversion rate [11–14] .…”