Converting a thick electrode into vertically aligned “Thin electrodes” by 3D-Printing for designing thickness independent Li-S cathode

Abstract

Sulfur cathodes with a high sulfur loading more than 3 mg cm−2 are essential for practical high-energy density Li-S batteries. However, Li+ transport is usually poor in thick cathodes, resulting in low capacity output, fast capacity decay and large overpotential. To tackle the issue of thick sulfur cathodes, a thickness-independent electrode structure is proposed for the first time which can transform a thick electrode into a combination of vertically aligned “thin electrodes”. Each “thin electrode” has a thickness of ~20 μm, which is independent of the overall thickness of electrode or sulfur loading. The “thin electrodes” substantially enhanced local accessibility to Li+ and e− and enabled similar electrochemical kinetics in spite of the total sulfur loading or thickness of the electrode. Accordingly, highly similar cycling performance and rate performance were demonstrated with the 250 μm and 750 μm (i.e. sulfur loadings of 2 and 6 mg cm−2) electrodes. This work demonstrates the concept and offers a new opportunity for designing high-loading cathodes and shall rise interests for other energy storage systems such as Li-ion batteries, Li-air batteries, etc.