Cruciform-hinged conjugated polymers unlock the conductivity-hydrophilicity-insolubility triad for high-performance aqueous sodium-ion batteries

Organic materials are ideal candidates for next-generation sustainable energy storage because of their structural tunability and eco-friendliness. However, their development in aqueous batteries has been limited by the challenge of simultaneously achieving high electrical conductivity, hydrophilicity, and insolubility. Here, we designed a conjugated polymer incorporating 65° cruciform hinges, which promote amorphous structures and expose polar groups at the electrode-electrolyte interface, thus breaking the limitation. When used as an anode for aqueous sodium-ion batteries, this polymer delivers specific capacities of 118 mAh g⁻¹ at 1 C and 80 mAh g⁻¹ at 20 C and retains 91% capacity after 35,000 cycles. Full pouch cells with high areal loadings (10 mg cm⁻¹) demonstrate ultrahigh power output (up to 50 C), excellent cycling stability over 10,000 cycles, and performance across a broad temperature range. This work establishes design principles for structurally simple, durable, and high-performance organic polymers, advancing intrinsically safe aqueous organic batteries toward real-world applications.