Sulfur/Oxygen Codoped Porous Hard Carbon Microspheres for High‐Performance Potassium‐Ion Batteries

• Published in: Advanced energy materials 2018-07, Vol.8 (19), p.n/a
• Main Authors: Chen, Mei, Wang, Wei, Liang, Xiao, Gong, Sheng, Liu, Jie, Wang, Qian, Guo, Shaojun, Yang, Huai
• Format: Article
• Language: English
• Subjects: Alternative energy sources; anode materials; Anodes; Carbon; Carbonization; Crystal defects; Deformation; Density functional theory; Electrode materials; Energy storage; Interlayers; Ion storage; Liquid crystals; Lithium-ion batteries; Microspheres; Porosity; porous carbon; Potassium; potassium ion batteries; Pyrolysis; Rechargeable batteries; Storage batteries; Sulfur; sulfur/oxygen codoping
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201800171

Potassium‐ion batteries (KIBs) are very promising alternatives to lithium‐ion batteries (LIBs) for large‐scale energy storage. However, traditional carbon anode materials usually show poor performance in KIBs due to the large size of K ions. Herein, a carbonization‐etching strategy is reported for making a class of sulfur (S) and oxygen (O) codoped porous hard carbon microspheres (PCMs) material as a novel anode for KIBs through pyrolysis of the polymer microspheres (PMs) composed of a liquid crystal/epoxy monomer/thiol hardener system. The as‐made PCMs possess a porous architecture with a large Brunauer–Emmett–Teller surface area (983.2 m2 g−1), an enlarged interlayer distance (0.393 nm), structural defects induced by the S/O codoping and also amorphous carbon nature. These new features are important for boosting potassium ion storage, allowing the PCMs to deliver a high potassiation capacity of 226.6 mA h g−1 at 50 mA g−1 over 100 cycles and be displaying high stability by showing a potassiation capacity of 108.4 mA h g−1 over 2000 cycles at 1000 mA g−1. The density functional theory calculations demonstrate that S/O codoping not only favors the adsorption of K to the PCMs electrode but also reduces its structural deformation during the potassiation/depotassiation. The present work highlights the important role of hierarchical porosity and S/O codoping in potassium storage. This work reports a novel sulfur/oxygen codoped porous hard carbon microspheres (PCMs) material for high‐performance potassium ion batteries. The as‐made PCMs anode delivers a high potassiation capacity of 226.6 mA h g−1 at the current density of 50 mA g−1 over 100 cycles. Most impressively, it can maintain an ultrahigh storage capacity of 108.4 mA h g−1 for more than 2000 cycles at 1000 mA g−1.