Sandwich structure of negative electrode using N-doped cellulose based carbon aerogel/graphene composite in ultra-battery

This study introduced a new ultra-battery (UB) structure by replacing N-doped monolithic carbon sheets instead of lead grids as a current collector. The carbon structure creates a sandwich construction (C|Pb|C), which serves as an alternative to lead grids and enhances the electrochemical properties of the battery. By removing lead grids, the weight of negative electrodes was reduced, and the specific capacity based on the total weight of the electrode (NAM + lead grids) increased by 1.3 times in deep discharge conditions. Additionally, the cycle life of the UB increased up to 2.35 times in HRPSoC mode. These improvements are due to the 3D and continuous conductive network path and higher charge acceptance of N-doped carbon sheets. These features facilitate the reversibility reaction of lead sulfate to lead by reducing the growth rate and size of created sulfate crystals. FESEM and X-ray analysis verified these phenomena. Linear sweep voltammetry (LSV) has shown that optimizing N-doping processes can control hydrogen evolution reaction (HER) in UBs. Furthermore, the UB's performance was improved and verified through charge/discharge, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) tests.