Binder-free barium-implanted MnO₂ nanosheets on carbon cloth for flexible zinc-ion batteries

The intrinsically low electrical conductivity and poor structural fragility of MnO₂ have significantly hampered the zinc storage performance. In this work, Ba²⁺-implanted δ-MnO₂ nanosheets have been hydrothermally grown on a carbon cloth (Ba-MnO₂@CC) as an extremely stable and efficient cathode material of aqueous zinc-ion batteries. The three-dimensionally porous architecture composed of interwoven thin MnO₂ nanosheets effectively shortens the electron/ion transport distances, enlarges the electrode/electrolyte contact area, and increases the active sites for the electrochemical reaction. Meanwhile, Ba²⁺ could function as an interlayer pillar to stabilize the crystal structure of MnO₂. Consequently, the as-optimized Ba-MnO₂@CC exhibits remarkable Zn²⁺ storage capabilities, such as a high capacity (305 mAh g⁻¹ at 0.2 A g⁻¹), prolonged lifespan (95% retention after a 200-cycling test), and superb rate capability. The binder-free cathode is also applicable for flexible energy storage devices with attractive properties. The present investigation provides important insights into designing advanced cathode materials toward wearable electronics.