Co₃O₄ anchored on ionic liquid modified PAN as anode materials for flexible lithium-ion batteries

Transition metal oxide Co₃O₄ is a candidate anode material for lithium-ion batteries (LIBs) due to its high theoretical specific capacity and easy preparation. However, unmodified Co₃O₄ suffers from distinctly inferior rate capability and poor cycling stability. Here, we design and fabricate a three-dimensional (3D) island bridge structure (IBS) Co₃O₄ anchored into IL [BMIm][N(CN)₂] modified PAN (Co₃O₄-PAN-IL) composite. The Co₃O₄ is uniformly dispersed microspheres, and IL modified PAN constitute a conductive network, which together form an IBS. The structure can effectively promote electron transfer, improve the specific surface area of the material, and alleviate the volume effect of cobalt oxide. More importantly, IL modified PAN has been considered as a highly conductive N-doping matrix after annealing. By virtue of these merits, the Co₃O₄-PAN-IL electrode demonstrates a high reversible capacity of 1499 mA h g⁻¹ at 0.5C. After 800 cycles, the capacity of 1239 mA h g⁻¹ was maintained, and the attenuation rate of each cycle was 0.022%. Compared with pure Co₃O₄, the electrochemical performance was significantly improved. The excellent electrochemical performance was due to the synergistic effect of nitrogen doping carbon network and uniformly dispersed Co₃O₄ particles. Furthermore, flexible pouch cells based on the cathode are further fabricated and demonstrate excellent electrochemical properties, highlighting the practical application of our deliberately designed electrode in flexible wearable electronics.