CoO/Co3O4 Hybrid Oxide Anode Synthesis Techniques and Performance Improvement for Super-Theoretical Capacity in Lithium-Ion Batteries

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The electrochemical instability of transition metal oxide (TMO)-based electrodes has hindered their broader adoption in lithium-ion batteries (LIBs), primarily due to rapid performance degradation. Addressing this challenge requires the development of TMO materials with enhanced lithium storage capacities and improved cycling stability. In this study, we report a facile hydrothermal synthesis of a CoO/Co₃O₄ hybrid oxide, followed by high-temperature calcination, aimed at boosting the electrochemical performance of these electrodes. Fluoroethylene carbonate (FEC) and vinylene carbonate (VC) additives were introduced to stabilize the Co₃O₄ interface, minimizing electrolyte decomposition and enhancing the electrode/electrolyte interface. At an optimized concentration of 2 wt%, these additives significantly improved cycling stability and capacity retention.To further address common issues like grain boundary cracking and void formation, calcination at 800°C with 2% FEC was employed, resulting in improved Li⁺ transport and structural stability. This optimized synthesis and additive strategy led to remarkable improvements in the CoO/Co₃O₄ anode’s electrochemical performance, achieving a super-theoretical capacity (STC) phenomenon. After 400 cycles at 0.5 C, the CoO/Co₃O₄ anode exhibited an extraordinary capacity of 1427.35 mAh g⁻¹, a significant increase from its initial capacity of 925 mAh g⁻¹.The observed STC is attributed to enhanced additive-driven electrolyte stabilization, the formation of a robust solid electrolyte interphase (SEI), and the mitigation of electrode surface cracking. Structural characterization via SEM, TEM, and BET analyses confirmed increased porosity and structural stability after prolonged cycling, further supporting the STC phenomenon. This study highlights the critical importance of tailored material synthesis and electrolyte engineering in overcoming the limitations of TMO-based anodes, paving the way for high-performance, long-lasting LIBs. Figure 1