Molecular Customization of Anode-Electrolyte Interfaces for Enhanced Stability and Reversibility in Aqueous Zinc-Carbon Capacitors

Abstract

Aqueous zinc-carbon capacitors display application potential in green power and high-end equipment owing to their high security, large power and sustainability. The water-rich zinc anode-electrolyte interface (AEI) and disordered zinc-ion diffusion are the culprits triggering corrosion reactions and dendrite growth, threatening the sustainability of aqueous zinc-carbon capacitors. Herein, a polyfunctional biomolecular, vitamin B₆, is introduced into the traditional aqueous electrolyte for customizing the functional AEI and fine-regulating the interfacial coordination environment of zinc ions. Specifically, the preferential anchoring of pyridine nitrogen enables trace vitamin (2.0 g L⁻¹) to construct a robust AEI and suppress corrosion reactions. The hydroxyl function zone provides high-octane guidance for zinc-ion diffusion at the AEI, resulting in flat zinc (002) oriented growth. Consequently, the Zn//Zn symmetrical cell features an ultrahigh cumulative capacity of 4.0 Ah cm⁻² under 34 % depth of discharge. The vitamin-optimized zinc-carbon capacitor features extended operational lifetimes exceeding 8 months (200 thousand cycles at 5.0 A g⁻¹), and demonstrates a high areal capacity of averaging 0.68 mAh cm⁻² and exceptional durability over 2000 hours at 1.0 A g⁻¹ under a high discharge depth of zinc anode (averaging 11.6 %). This work offers valuable insights into sustainable and cost-effective zinc-carbon capacitors.