Chinese team develops sunlight-assisted lithium–sulfur battery

Researchers at Northwestern Polytechnical University in China have developed a sunlight-assisted lithium–sulfur battery that addresses key challenges in lithium–sulfur technology, notably the slow and inefficient sulfur chemistry. By integrating a flexible photoelectrode composed of polypyrrole-modified, nitrogen-doped titanium dioxide grown on carbon cloth, the battery uses light to accelerate sulfur redox reactions during charging. A polymer–TiO2 layer creates an internal electric field that effectively separates charges, reducing recombination and enhancing the use of visible light to drive chemical processes. This design enables near-theoretical energy storage performance, partial solar charging, and improved cycling stability. The new battery demonstrates significant performance improvements: the resistance to sulfur reactions (Tafel slope) decreases from 122 to 48 mV per decade, lithium sulfide nucleation time shortens from 3,600 to 3,010 seconds, and capacity increases by 17%. It can harvest energy both electrically and via sunlight, achieving a solar-to