Organic redox-active compounds represent a promising family of materials for metal-ion batteries. They can be produced from renewable resources and contain no toxic or expensive heavy metals. Moreover, they are much less specific to the nature of the mobile ion, such as Li⁺, Na⁺ or K⁺, which facilitates the development of cheaper alternatives to the currently dominating lithium-ion battery technology. Here we report stable and ultrafast lithium-, sodium- and potassium-ion batteries (LIBs, SIBs and PIBs) comprising a polymer cathode based on hexaazatriphenylene, which is synthesized from 3,3′-diaminobenzidine and triquinoyl. Using LIBs as a model system, it is shown that the application of dimethoxyethane (DME) as the electrolyte solvent is crucial for achieving a superior performance. Using a DME-based electrolyte, a specific capacity of 169 mA h g⁻¹ is reached for PIBs at an impressive current density of 10 A g⁻¹ (charging/discharging in ca. one minute) after 4600 cycles. At a lower current density of 50 mA g⁻¹, the capacity of PIBs approaches 245 mA h g⁻¹. The performance of the designed polymer cathode is among the best ever reported for K-ion battery materials in terms of specific capacity, energy and power density. The polymer-based devices demonstrated record cycling stability, outperforming all non-aqueous potassium-ion batteries reported to date.

Polymeric aromatic amines were shown to be very promising cathodes for lithium-ion batteries. Surprisingly, these materials are scarcely used for designing post-lithium batteries. In this Letter, we investigate the application of the high-voltage poly(N-phenyl-5,10-dihydrophenazine) (p-DPPZ) cathodes for K-ion batteries. The designed batteries demonstrate an impressive specific capacity of 162 mAh g^–1 at the current density of 200 mA g^–1, operate efficiently at high current densities of 2–10 A g^–1, enabling charge and discharge within ∼1–4 min, and deliver the specific capacity of 125–145 mAh g^–1 with a retention of 96 and 79% after 100 and 1000 charge–discharge cycles, respectively. Finally, these K-ion batteries with polymeric p-DPPZ cathodes showed rather outstanding specific power of >3 × 10⁴ W kg^–1, thus paving a way to the design of ultrafast and durable high-capacity metal-ion batteries matching the increasing demand for high power and high energy density electrochemical energy storage devices.