Synergistic coupling of optical field and built-in electric field for lithium-sulfur batteries with high cyclabilities and energy densities

Abstract

Photo-assisted lithium sulfur batteries (PA-LSBs) provide vital and sustainable protocols for promoting sulfur redox reactions via powerful photoinduced effects. However, precise control of the stepwise adsorption, diffusion and photocatalytic conversion of polysulfides at the surface of photocatalysts is required to accelerate the photo-assisted process. Herein, optical field and built-in electric field synergistically-assisted LSBs are developed with a p-n junction of Co3O4-TiO2 on the carbon cloth, possessing a spontaneously generated built-in electric field and a well-matched energy band structure with sulfur redox reactions. Under light irradiation, the directional migration of soluble polysulfides and the space separation of photogenerated carriers are achieved with the synergistical coupling of the optical field and built-in electric field to precisely regulate the selective deposition of Li2S and inhibit the shuttle effect via an effective photocatalytic-promoted process, leading to a maximum capacity of 1087 mAh g−1 at 2 C and a low capacity attenuation of 0.068% per cycle at 5 C. A high areal capacity of 9.6 mAh cm−2 and a great potential photo-charge process can be realized with light irradiation. Furthermore, the stability of lithium metal anodes is improved accordingly. This work demonstrates a new insight to develop high-performance LSBs with a multifield synergistical coupling protocol.

Keywords

• Photo-assisted lithium-sulfur batteries
• Titanium dioxide
• Cobalt tetroxide
• The shuttle effect
• The built-in electric field