Searching High-Potential Dihydroxynaphthalene Cathode for Rocking-Chair All-Organic Aqueous Proton Batteries

The lack of acid-proof high-potential cathode largely limits the development and competitiveness of proton batteries. Herein, the authors systematically investigated six dihydroxynaphthalenes (DHNs) and found that 2,6-DHN delivered the best cathode performance in proton battery with the highest redox potential (0.84 V, vs SHE) and a specific capacity of 91.6 mAh g-1 at 1 A g-1. In situ solid-state electropolymerization of DHNs is responsible for the voltage and capacity fading of DHNs, and 2,6-DHN's excellent electrochemical performance is derived from its high polymerization energy barrier. By compounding with rGO, the 2,6-DHN/rGO electrode can maintain a specific capacity of 89 mAh g-1 even after 12 000 cycles at 5 A g-1. When it is paired with the 2,6-dihydroxyanthraquinone (DHAQ) anode, the assembled rocking-chair all-organic proton battery exhibited a high cell voltage of 0.85 V, and excellent energy/power densities (70.8 Wh kg-1/850 W kg-1). This study showcases a new-type high-potential proton-containing organic cathode and paves the way for constructing a high-voltage rocking-chair proton battery. Also, in situ solid-state electropolymerization will inspire the further study of phenol-based small-molecule electrodes. In this work, six different dihydroxynaphthalenes (DHNs) as electrodes of aqueous proton batteries (APBs) are studied and it is found that 2,6-DHN delivers the highest electrode potential (0.84 V, vs SHE). Experimental and calculation results indicate that in situ solid-state electropolymerization is responsible for DHNs' electrochemical behaviors. The assembled 2,6-dihydroxyanthraquinone/2,6-DHN rocking-chair all-organic APBs exhibit high voltage and excellent energy/power densities.image

Automated summary

This study presents a new-type high-potential organic cathode material for proton batteries and paves the way for constructing high-voltage rocking-chair proton batteries. The study also highlights the impact of in situ solid-state electropolymerization on electrode performance and inspires further research on phenol-based small-molecule electrodes.