Coordination Defect‐Induced Lewis Pairs in Metal−Organic Frameworks Boosted Sulfur Kinetics for Bifunctional Photo‐Assisted Li−S Batteries

• Published in: Advanced functional materials 2024-10, Vol.34 (41), p.n/a
• Main Authors: Wu, Jia‐Yi, Wang, Yue, Song, Li‐Na, Wang, Yi‐Feng, Wang, Xiao‐Xue, Li, Jun‐Feng, Xu, Ji‐Jing
• Format: Article
• Language: English
• Subjects: Charge transfer; Charging; electrochemical performance; Electrons; Kinetics; Ligands; Lithium sulfur batteries; photocatalyst; photo‐assisted Li−S batteries; Polysulfides; shuttle effect; Sulfur
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202404211

The photo‐assisted strategy is regarded as a crucial approach to enhance the conversion kinetics of polysulfides in lithium–sulfur (Li–S) batteries. However, the development of photo‐assisted Li–S batteries still faces important challenges, such as the rapid recombination of photogenerated electron−holes on cathode and more severe shuttle effect. Herein, a breakthrough in overcoming the challenges has been made by constructing a promising photo‐assisted Li−S battery based on semiconducted metal−organic frameworks. During the discharging progress, the photoexcited electrons generated by H2BPDC ligand based on ligand‐to‐metal charge transfer (LMCT) effect, are injected into the Ti‐oxo clusters in Ti‐MOF, thereby facilitating the sulfur reduction to Li2S. And photoexcited holes are capable of promoting the decomposition kinetics of Li2S during charging. More importantly, the stronger chemical interaction between Ti‐BPDC‐d and polysulfides under light inhibits the polysulfides dissolution and shuttling, which fundamentally addresses the issue of light‐accelerated shuttling. As a result, the photo‐assisted Li–S batteries deliver a reversible capability of 1090.21 mAh g−1 at 0.2 C with a capacity retention of 82.91% over 150 cycles, and a superior rate capability of 673.58 mAh g−1 at 5 C. The findings are promising in advancing the design principles for photo‐rechargeable Li−S batteries. A new perspective for a photo‐assisted Li−S battery systems based on Ti‐MOF with ligand defects is proposed, which improves the efficiency of photogenerated electron–holes separation, greatly promoting redox reaction kinetics. Additionally, the introduction of light enhances the chemical affinity between Ti‐BPDC‐d and polysulfides, which inhibits the LiPSs shuttling.