Confluence of ZnO and PTFE Binder for Enhancing Performance of Thin-Film Lithium-Ion Batteries

Developing anode materials with high specific capacity and cycling stability is vital for improving thin-film lithium-ion batteries. Thin-film zinc oxide (ZnO) holds promise due to its high specific capacity, but it suffers from volume changes and structural stress during cycling, leading to poor battery performance. In this research, we ingeniously combined polytetrafluoroethylene (PTFE) with ZnO using a radio frequency (RF) magnetron co-sputtering method, ensuring a strong bond in the thin-film composite electrode. PTFE effectively reduced stress on the active material and mitigated volume change effects during Li⁺ ion intercalation and deintercalation. The composite thin films are thoroughly characterized using advanced techniques such as X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy for investigating correlations between material properties and electrochemical behaviors. Notably, the ZnO/PTFE thin-film electrode demonstrated an impressive specific capacity of 1305 mAh g⁻¹ (=7116 mAh cm⁻³) at a 0.5C rate and a remarkable capacity retention of 82% from the 1st to the 100th cycle, surpassing the bare ZnO thin film (50%). This study provides valuable insights into using binders to stabilize active materials in thin-film batteries, enhancing battery performance.