Development and understanding of the lithiation/de-lithiation mechanism of a low cobalt and nickel-rich cathode material for lithium‐ion batteries

Abstract

Nickel-rich LiNixMnyCo1−x−yO2 (NMC, with x ≥ 0.6) layered oxides are regarded as cathode candidates for high-energy density lithium-ion batteries (LIBs). However, this technology faces several challenges due to the scarcity of crucial raw materials such as cobalt precursors and the negative environmental impact of their extraction process. It is therefore, it becomes imperative to develop low cobalt content cathode compositions that offer alternative options with comparable electrochemical performance. Herein, we have used a systematic approach to modify the composition while keeping all other properties (particle size and morphology) constant to synthesise low-Co-cathode materials, namely LiNi0·8Mn0·1Co0·1O2 (NMC-10 %) and LiNi0·8Mn0·15Co0·05O2 (NMC-5%). A co-precipitation route using a continuous stirred thank reactor was used for synthesis. The physico-chemical properties, electrochemical performances, cycling stability, and rate capabilities of NMC-5% materials are comparable to those of NCM-10 % materials. NMC-10 % and NMC-5% half cells show initial specific discharge capacities of 191 mAh.g−1, and 185 mAh.g−1, respectively, in a voltage range of 2.8–4.3 V (vs. Li+/Li). The NMC-5% exhibits excellent thermal stability, characterized by a predominant exothermic peak at 432 °C and significantly lower total heat energy when compared to NMC-10 % counterpart, which displayed its main exothermic peak at 339 °C. The structural and electronic changes of both materials were evaluated through in operando synchrotron-based X-ray techniques. Regardless of the cobalt content, both materials show comparable structural and electronic evolution upon the de-intercalation/intercalation of Li+ ions. An irreversible phase transition at the first delithiation was observed as emphasized by diffraction of synchrotron radiations.