High areal capacity, long cycle life Li-O₂ cathode based on highly elastic gel granules

We introduce a “gelating-cutting” strategy to improve specific areal capacity and cycle life for Li-O₂ cathode. Conventional Li-O₂ cathode with liquid electrolyte is gelated with highly elastic crosslinked polymer and cut into 50–200 µm granules. The gaps between the packed gel granules efficiently induce oxygen to the inner part of the cathode, leading to even Li₂O₂ growth in thick cathode. Meanwhile, the elasticity of the polymer chain helps to keep good contact between carbon and Li₂O₂ nanoparticles, which facilitates the electron transfer and improves the cyclability. Without any catalyst, the granular gel cathode is able to run 170 cycles at a fixed capacity of 1000 mA h g_carbon⁻¹, or maintains a specific capacity higher than 10,500 mA h g_carbon⁻¹ (12.6 mA h cm⁻²) during 11 cycles of full discharge-charge. Since good contact is the precondition to any electrochemical reaction, our strategy is a general way to enhance the performance of Li-O₂ cathodes.