Tissue-derived carbon microbelt paper: a high-initial-coulombic-efficiency and low-discharge-platform K-storage anode for 4.5 V hybrid capacitors

• Published in: Energy & environmental science 2022-01, Vol.15 (1), p.158-168
• Main Authors: Zhang, Taoqiu, Mao, Zhiefei, Shi, Xiaojun, Jin, Jun, He, Beibei, Wang, Rui, Gong, Yansheng, Wang, Huanwen
• Format: Article
• Language: English
• Subjects: Activated carbon; Anodes; Capacitors; Carbon; Discharge; Electrode materials; Electrolytes; Flux density; Graphite; Hybrid systems; Polymers; Potassium
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d1ee03214c

Hard carbon (HC) is a promising anode material for K + -storage due to its randomly oriented turbostratic structure. However, most reported HC anodes exhibit low initial coulombic efficiency (ICE) and no obvious discharge platform during K + -intercalation/deintercalation, thus restricting their practical application. Herein, cheap and renewable sanitary tissue is utilized as the precursor to construct a flexible self-supporting hard carbon microbelt paper (HCMB). As a binder-free anode, the HCMB can achieve a high ICE value of 88% with a high charge capacity below 1 V (204 mA h g −1 at 100 mA g −1 ), excellent rate capability (151 mA h g −1 at 1000 mA g −1 ) and superior cycling stability in a conventional KPF 6 -based electrolyte. More importantly, the HCMB-based anodes exhibit a rather low discharge platform, which is close to a graphite anode (0.25 V vs. K/K + ). To demonstrate its practical use, a novel 4.5 V potassium ion capacitor (PIC) device is successfully constructed based on the HCMB anode and an activated carbon cathode together with a gel polymer electrolyte. The energy density of this hybrid system is up to 152 W h kg −1 , and is still maintained as high as 112 W h kg −1 at a high power density of 17 500 W kg −1 . In addition, the effect of the carbonization temperature on the K + -storage behavior of HCMB and its comparison with carbon counterparts (graphite and soft carbon) are systematically investigated. Sanitary tissue is utilized as the precursor to construct a hard carbon microbelt paper (HCMB), which can be employed as a high-initial-coulombic-efficiency and low-discharge-platform K + -storage anode for 4.5 V hybrid capacitors.