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Despite the tremendous success of Li-ion battery based upon liquid electrolytes and oxide positive electrodes, their widespread application is limited due to the safety concerns originated from the oxygen release. Consequently, the oxygen release causes phase transformation, which also leads to the mechanical failure of a battery. Thus, this paper presents a detailed multiphase-field model (PFM) to predict chemo-mechanical properties of oxide based battery electrodes. The PFM considers the chemical composition change, the associated phase transformation and the stress generation in the bulk as well as at the surface of the electrode. This model is applied to capture the development and evaluation of phase transformation mechanism, which occurs at elevated temperatures in the partially delithiated Li 0.45 CoO 2 (LCO) material. Our results indicate that the major oxygen concentration change occurs in the narrow region between the phases, and the compressive stress is generated inside the bulk LCO, whereas tensile stress is observed within the LCO-gas phase interface. In addition, an important contribution of this work is the derivation of a new set of thermodynamic and kinetic data of the oxygen release. The modeling results allow for a direct comparison with the in-situ transmission electron microscopy (TEM) measurements reported by Sharifi-Asl et al. [ Nano Letters , 17(4), 2165, 2017]. Thus, our findings provide new qualitative and quantitative understandings of the LCO phase transformations and the kinetics of oxygen release. [ABSTRACT FROM AUTHOR]

Widespread application of Li‐ion batteries (LIBs) in large‐scale transportation and grid storage systems requires highly stable and safe performance of the batteries in prolonged and diverse service conditions. Oxygen release from oxygen‐containing positive electrode materials is one of the major structural degradations resulting in rapid capacity/voltage fading of the battery and triggering the parasitic thermal runaway events. Herein, the authors summarize the recent progress in understanding the mechanisms of the oxygen release phenomena and correlative structural degradations observed in four major groups of cathode materials: layered, spinel, olivine, and Li‐rich cathodes. In addition, the engineering and materials design approaches that improve the structural integrity of the cathode materials and minimize the detrimental O2 evolution reaction are summarized. The authors believe that this review can guide researchers on developing mitigation strategies for the design of next‐generation oxygen‐containing cathode materials where the oxygen release is no longer a major degradation issue. [ABSTRACT FROM AUTHOR]