Dual active center phenothiazine cathode synergized with acetonitrile solvation modulation for high performance zinc organic battery

P-type organic materials are promising electrode materials, but their capacity is limited owing to the low proportion of active center parts within the whole structures (usually less than 100 mAh g⁻¹). To overcome this challenge, this study proposes a dual active center redox system based on phenothiazine (PTZ) molecule. DFT calculation show that the aromaticity of PTZ is enhanced during stepwise oxidation, and the extension of its π-conjugated system not only enhances structural stability but also facilitates rapid redox reactions, as evidenced by the smaller Nuclear Independent Chemical Shift (NICS(1)zz) value and reduced energy gap difference. To breakthrough kinetic limitations, the solvation environment was precisely modulated by acetonitrile (ACN) introduction. First-principles simulations reveal this additive restructures the inner solvation sheath into a looser configuration, reducing the de-solvation energy barrier and enabling remarkable rate performance. The assembled Zn||PTZ battery achieve a high specific capacity of 126 mAh g⁻¹ at 0.05 A g⁻¹ and exhibit excellent stability without degradation for 10,000 cycles at 5 A g⁻¹. Notably,the system maintaining 80.1% capacity retention when the current density was scaled up 100-fold from 0.1 to 10 A g⁻¹, representing a 10.8% enhancement compared to pure aqueous systems. It ultimately achieved an energy density of 134.58 Wh kg⁻¹ and a power density of 6201.67 W kg⁻¹. Additionally, the Zn||PTZ battery exhibits 75.9% capacity retention at -20°C, indicating remarkable low temperature tolerance. More importantly, even under high mass loading conditions of 12 mg cm⁻², it still demonstrates excellent mass transfer and kinetic stability. Finally, the multi-step reversible energy storage mechanism of PTZ electrodes was thoroughly investigated and discussed via a series of in-situ and ex-situ characterizations.