Binary-Metal-Engineered Aqueous Binder with Enhanced Ionic Conductivity and Adhesion Strength for Silicon Anodes

As a promising high-performance anode, silicon (Si) has a high theoretical specific capacity and low working voltage; however, its substantial volume expansion during lithiation would heavily disrupt electron and ion pathways within the electrode, ultimately causing capacity degradation. Herein, inspired by the “facilitated diffusion through ion channels” mode of biological cellular material in the cell membrane, a novel aqueous binder of binary-metal-engineered alginate-Prussian blue analogs (Alg-PBAs) via a sequential coprecipitation reaction is proposed. The ionic conductivity (1.718 × 10–4 S cm–1) and adhesion strength (4.71 N cm–1) of the Alg-PBA binder are significantly improved by controlling the distribution of metal ions and PBA crystals. The obtained Alg-PBA binder with a highly conductive network and rich polar groups (−OH, −C═O, −C≡N) could not only form a uniform conductive nanolayer on the surface of Si particles but also establish an integrated structure within Si particles and the current collector. As a result, the designed Alg-PBA binder enables the Si anode with a relatively low overall resistance, an enhanced capacity retention even at a high mass loading of 2.2 mg cm–2, and a diminished polarization at a high current density of 2.1 A g–1. These results provide a promising pathway for the development of high-energy-density Si-based lithium-ion batteries.