High yield porous carbon framework with co-active BN sites to promote polyiodide conversion for high performance Zn-I batteries.

Aqueous Zn-I batteries have garnered significant attention due to their high abundance and safety. However, the sluggish iodine redox kinetics and undesirable shuttle effect severely hindered their wider application. Herein, dual doping of B and N provides an effective strategy to modulates chemical properties and electron distributions of carbon hosts, resulting in a high performance of Zn-I batteries. The local electron redistribution enhances electron density at the Fermi level of the carbon host, thereby improving intrinsic conductivity. Additionally, combining experiments and DFT calculations reveal that NB center sites are benefited in suppressing shuttle effects, strengthening interactions with iodide species and facilitating catalytic conversion kinetics. Notably, Zn-I batteries fabricated with B and N co-doped porous carbon (BNAC) achieve an outstanding capacity (231.7 mAh g at 0.1 A g) and excellent cycling stability (capacitance retention of 98% after 4500 cycles). This study not only provides valuable insights into the design of advanced carbon materials but also clarifies the active sites in B/N co-doped carbon materials, offering guidance for the rational design of carbon-based electrode materials for Zn-I batteries.