Robust Micro‐Sized and Defect‐Rich Carbon–Carbon Composites as Advanced Anodes for Potassium‐Ion Batteries

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-01, Vol.20 (4), p.e2305841-n/a
• Main Authors: Quan, Zhuohua, Wang, Fei, Wang, Yuchen, Liu, Zhendong, Zhang, Chengzhi, Qi, Fulai, Zhang, Mingchang, Ye, Chong, Tan, Jun, Liu, Jinshui
• Format: Article
• Language: English
• Subjects: Anodes; Carbon; carbon anodes; Carbon-carbon composites; Chemical bonds; Composite materials; Crystal defects; Crystallization; defect‐rich expanded‐graphite composites (EGC); Heat treatment; Ion migration; Potassium; potassium‐ion batteries; Pyrolysis; Rechargeable batteries; robust micro‐sized structures; Robustness; Structural stability; Tortuosity
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202305841

Pitch‐derived carbon (PC) anode features the merits of low‐cost, rich edge‐defect sites, and tunable crystallization degree for potassium ion batteries (PIBs). However, gaining the PC anode with both rich edge‐defect sites and robust structure remains challenging. Herein, micro‐sized and robust PC/expanded‐graphite (EG) composites (EGC) with rich edge‐defect sites are massively synthesized via melting impregnation and confined pyrolysis. The PC is in situ encapsulated in micro‐sized EG skeleton with robust chemical bonds between PC and EG after thermal treatment, endowing the structural stability as micro‐sized carbon–carbon composites. The confinement effect originating from EG skeleton could suppress the crystallization degree of the PC and contribute rich edge‐defect sites in EGC composites. Additionally, the EG skeleton inside EGC could form continuous electronic conduction nets and establish low‐tortuosity carbonaceous electrodes, facilitating rapid electron/ion migration. While applied in PIBs, the EGC anode delivers a reversible capacity that up to 338.5 mAh g‒1 at 0.1 A g‒1, superior rate performance of 127.5 mAh g‒1 at 5.0 A g‒1, and long‐term stability with 204.8 mAh g‒1 retain after 700 cycles at 1.0 A g‒1. This novel strategy highlights an interesting category of heterogeneous carbon–carbon composite materials to keep pace with the demand for the future PIBs industry. Breaking the trade‐off between rich edge‐defect sites and robust structure for pitch‐derived carbon anode remains challenging. In this work, heterogeneous carbon–carbon composites with robust structure are proposed.. The confinement effect originating from expanded‐graphite skeletons suppresses the crystallization degree of pitch‐derived carbon and contributes rich edge‐defect sites in composite, providing high capacity and stability for potassium ion batteries.