A Full Li–S Battery with Ultralow Excessive Li Enabled via Lithiophilic and Sulfilic W2C Modulation

• Published in: Chemistry : a European journal 2020-12, Vol.26 (68), p.16057-16065
• Main Authors: Wei, Benben, Shang, Chaoqun, Akinoglu, Eser Metin, Wang, Xin, Zhou, Guofu
• Format: Article
• Language: English
• Subjects: Batteries; Cathode region; Chemisorption; Chemistry; Dendritic structure; Kinetics; Li dendrites; Lithium; Lithium sulfur batteries; Li–S batteries; Nanocrystals; Nucleation; Plateaus; Reaction kinetics; Redox reactions; shuttle effect; Specific capacity; Sulfur; ultralow cell balance; W2C nanocrystals
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202002822

The practical application of Li–S batteries demands low cell balance (Licapacity/Scapacity), which involves uniform Li growth, restrained shuttle effect, and fast redox reaction kinetics of S species simultaneously. Herein, with the aid of W2C nanocrystals, a freestanding 3D current collector is applied as both Li and S hosts owing to its lithiophilic and sulfilic property. On the one hand, the highly conductive W2C can reduce Li nucleation overpotentials, thus guiding uniform Li nucleation and deposition to suppress Li dendrite growth. On the other hand, the polar W2C with catalytic effect can enhance the chemisorption affinity to lithium polysulfides (LiPSs) and guarantee fast redox kinetics to restrain S species in cathode region and promote the utilization of S. Surprisingly, a full Li–S battery with ultralow cell balance of 1.5:1 and high sulfur loading of 6.06 mg cm−2 shows obvious redox plateaus of S and maintains high reversible specific capacity of 1020 mAh g−1 (6.2 mAh cm−2) after 200 cycles. This work may shed new sights on the facile design of full Li–S battery with low excessive Li supply. Low cell balance of Li–S batteries is realized with regular Li dendrite and enhanced LiPSs redox kinetics via lithiophilic and sulfilic W2C/C nanofibers.