Nickel–Platinum Alloy Nanocrystallites with High‐Index Facets as Highly Effective Core Catalyst for Lithium–Sulfur Batteries

• Published in: Advanced functional materials Vol. 32; no. 27
• Main Authors: Wang, Zhen‐Yu, Zhang, Bohai, Liu, Sheng, Li, Guo‐Ran, Yan, Tianying, Gao, Xue‐Ping
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.07.2022
• Subjects: Alloys; Catalysts; Catalytic activity; catalytic hosts; Cathodes; Crystallites; Damping capacity; Graphene; high‐index facets; Kinetics; Lithium; Lithium sulfur batteries; Materials science; Nickel; nickel–platinum alloys; Platinum; Platinum base alloys; Structural design; Sulfur; sulfur cathodes
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202200893

Elemental sulfur possesses an ultra‐high theoretical specific capacity, while the practical application of sulfur in lithium–sulfur (Li–S) batteries is seriously hindered by the sluggish redox kinetics and serious shuttle effect. Enhancing the catalytic activity of the sulfur host by a rational structural design is the key to address these issues. Herein, for the first time, concave‐nanocubic (CNC) nickel–platinum (Ni–Pt) alloys bounded by high‐index facets (HIFs) are introduced as the core catalyst of sulfur for Li–S batteries. It is demonstrated that the CNC Ni–Pt alloy crystallites dispersed uniformly on graphene exhibit a high electrochemical activity to drive the conversion from intermediate lithium polysulfides to solid discharged products. Benefiting from the accelerated redox kinetics by HIFs, the cathode delivers a low capacity damping of 0.025% per cycle for 1000 cycles at 1 C rate. In particular, a high reversible capacity of 664.9 mAh g−1‐cathode with cathode as active material can be achieved with high sulfur loading (8.8 mg cm−2) and low electrolyte usage (5 µL mgs−1). This study focuses on improving the catalytic activity of sulfur hosts by modulating the exposed facets of core catalyst and provides a new path for the structure optimizing of host materials in Li–S batteries. Well‐designed concave‐nanocubic nickel–platinum alloy crystallites with high‐index facets (HIFs), dispersed uniformly on graphene, are prepared as the catalytic host for lithium–sulfur batteries. The HIFs of the alloy nanocrystallites exhibit a high intrinsic electrocatalytic activity for the conversion of intermediate lithium polysulfides and discharged products. Therefore, the sulfur cathode delivers enhanced electrochemical performances.