Improving energy density of battery-type electrode material by growing β-Ni(OH)2 in situ on biochar for hybrid supercapacitors

• Published in: Journal of energy storage Vol. 100; p. 113530
• Main Authors: Jia, Baojin, Zhou, Qianyun, Gao, Leiying, Wang, Lulu, Liu, Mingyang, Xu, Shiwu, Zhang, Genlin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.10.2024
• Subjects: Biochar; Flower-like structure; Hybrid supercapacitors; Situ growth; Transition-metal hydroxides; Hybrid supercapacitors; Transition-metal hydroxides; Biochar; Flower-like structure; Situ growth
• ISSN: 2352-152X
• DOI: 10.1016/j.est.2024.113530

The insufficient energy density of electrode materials has hindered the popularity and application of supercapacitors. The construction of hybrid supercapacitors offers an ideal solution by combining transition-metal hydroxides with high specific capacity and biochar with excellent conductivity. In this study, an electrode material (β-Ni(OH)2@AC22 composite) was created by in situ growth flower-like β-Ni(OH)2 nanosheets on biochar (AC) that extracted from the seed coat of Xanthoceras sorbifolium Bunge. This β-Ni(OH)2@AC22 composite exhibited a remarkable specific capacity of 617.5C g−1 (1 A g−1), nearly four times that of AC, and remarkable cycling stability (85.6 % retention after 5000 cycles). Using this composite as the positive electrode and biochar as the negative electrode, the assembled battery-type hybrid supercapacitors (HSCs) achieved a specific capacity of 92.75C g−1 (1 A g−1). The HSCs demonstrated a specific energy of 57.9 Wh kg−1, a specific power of 750.9 W kg−1, and even maintained 42.2 Wh kg−1 at a maximum specific power of 6049.4 W kg−1. The device maintained a specific capacity of about 78.7 % after 7000 charging/discharging cycles, demonstrating good practical performance. These results highlight the practical application potential of the prepared composites in supercapacitors, with biochar serving as a basis for enhancing the electrochemical performance of supercapacitors. [Display omitted] •Spine-like biochar with large SSA was prepared from Xanthoceras sorbifolium Bunge seed coats.•Flower-like nanosheets through by growing β-Ni(OH)2 on biochar in situ were developed.•Application of biochar in the electrode materials suppressed volume expansion and improved cycling stability.•Assembled hybrid supercapacitors showed the excellent electrochemical performance.