Hierarchical and Highly Stable Conductive Network Cathode for Ultraflexible Li–S Batteries

Flexible Li–S batteries have great potential for next-generation energy storage which can meet the rising demand of rollable displays and wearable electronic devices because of the high theoretical energy density and competitive price. Here, we design and fabricate an integrated electrode with hierarchical structure and interconnected 3D conductive networks as a cathode of flexible Li–S batteries. The composite cathode exhibits high electrochemical performance and cycling stability. The initial reversible discharge capacity is 1312 mA h g–1 at 0.2 C with sulfur load 2.0 mg cm–2, and the capacity decay rate is 0.09% per cycle within 500 cycles at current of 1 C. Notably, the composite electrode can sustain 15.2 MPa stress with 10% strain and retain structural integrity after 200 000 bending cycles, the highest number of bending cycles found to date for any flexible S cathodes. The soft package batteries with different sizes and shapes are fabricated, and they exhibit extraordinary flexibility and stability after bending and flattening over 2100 times. Moreover, their potential applications in rollable displays, flexible lighting, and wearable electronic devices are also investigated.