Dual-Site Dual-Charge Carrier Mechanism for High-Energy and Long-Life Metal-Free Hybrid Energy Storage Devices

Designing organic electrode materials that achieve high energy density without compromising long-term cycling stability is a grand challenge in energy storage research. Here, this is addressed by introducing a unique dual-site, dual-charge carrier mechanism leveraging a multielectron nitro-triazine trimeric cathode and two non-metallic charge carriers (NH₄⁺ and H⁺). We present a highly redox-active and exceptionally stable nitro-triazine molecule, 2,4,6-tris(4-nitrophenyl)-1,3,5-triazine (TNPT), featuring nitro and triazine groups that enable multiple redox sites, extended π-conjugation, strong-hydrogen bonding affinity, and π–π stacking capabilities. The dual-redox nitro and triazine groups interact synergistically with NH₄⁺ and H⁺ in an optimized 3 m NH₄OTF electrolyte, leveraging tetrahedral hydrogen bonding and Grotthuss/special pair dance proton transfer, boosting fast kinetics and exceptional cycling stability. A nitrogen-doped graphene oxide(NG)/TNPT nanocomposite delivers an impressive specific capacity of 263 mAh g⁻¹ at 0.1 A g⁻¹, with excellent cyclic stability-retaining 97.8% capacity over 10 000 cycles. Furthermore, the metal-free hybrid full-cell device, consisting of a nanoporous carbon capacitive anode and the NG@TNPT battery cathode, achieves a remarkable energy density of 45.11 Wh kg⁻¹, the highest reported for metal-free energy storage systems to date. This work provides a new design strategy for developing high-energy, long-life, metal-free hybrid energy storage devices.