Wood-derived carbon as self-supporting cathode and current collector for static zinc-iodine batteries

Despite advancements in cathode materials for static zinc-iodine batteries, current collectors remain underutilized, contributing little to the overall specific capacity. This study explores the use of novel pine wood-derived carbon (PWC) as a current collector for cathodes. When employed directly as the cathode, PWC's unique structure, characterized by abundant straight channels, enhances electrolyte penetration and ion exchange, resulting in a specific capacity of 0.14 mAh cm^-2 at 1 mA cm^-2-more than 2.3 times greater than those of conventional carbon and metal collectors. Ex situ analyses indicate that PWC promotes the deposition of solid salts akin to the electrolyte, forming a protective layer that improves coulombic efficiency during charge-discharge cycles. Furthermore, the C-OH bonds at the PWC interfaces facilitate redox reactions between iodine species, which are crucial for energy storage and release. Additionally, an activated carbon cathode with PWC as the current collector achieves a specific capacity of 0.62 mAh cm^-2 at 2 mA cm^-2, exceeding the performance of similar cathodes constructed with commercial carbon paper. The PWC-based activated carbon cathode also exhibits good cycle life and significant potential for practical applications.