@article{Li_Yang_Yang_Wang_Rong_Wang_Xu_Kang_Dong_2021, title={Towards High-Energy and Anti-Self-Discharge Zn-Ion Hybrid Supercapacitors with New Understanding of the Electrochemistry}, volume={13}, url={https://www.nmlett.org/index.php/nml/article/view/861}, DOI={10.1007/s40820-021-00625-3}, abstractNote={<p>Aqueous Zn-ion hybrid supercapacitors (ZHSs) are increasingly being studied as a novel electrochemical energy storage system with prominent electrochemical performance, high safety and low cost. Herein, high-energy and anti-self-discharge ZHSs are realized based on the fibrous carbon cathodes with hierarchically porous surface and O/N heteroatom functional groups. Hierarchically porous surface of the fabricated free-standing fibrous carbon cathodes not only provides abundant active sites for divalent ion storage, but also optimizes ion transport kinetics. Consequently, the cathodes show a high gravimetric capacity of 156&nbsp;mAh&nbsp;g<sup>−1</sup>, superior rate capability (79&nbsp;mAh&nbsp;g<sup>−1</sup> with a very short charge/discharge time of 14&nbsp;s) and exceptional cycling stability. Meanwhile, hierarchical pore structure and suitable surface functional groups of the cathodes endow ZHSs with a high energy density of 127&nbsp;Wh&nbsp;kg<sup>−1</sup>, a high power density of 15.3&nbsp;kW&nbsp;kg<sup>−1</sup> and good anti-self-discharge performance. Mechanism investigation reveals that ZHS electrochemistry involves cation adsorption/desorption and Zn<sub>4</sub>SO<sub>4</sub>(OH)<sub>6</sub>·5H<sub>2</sub>O formation/dissolution at low voltage and anion adsorption/desorption at high voltage on carbon cathodes. The roles of these reactions in energy storage of ZHSs are elucidated. This work not only paves a way for high-performance cathode materials of ZHSs, but also provides a deeper understanding of ZHS electrochemistry.</p> <p>Highlights:</p> <p>1 A surface engineering strategy was proposed to design hierarchically porous structure on fibrous carbon cathodes with O/N heteroatom functional groups.<br>2 High-energy and anti-self-discharge Zn-ion hybrid supercapacitors (ZHSs) were realized.<br>3 ZHS electrochemistry was investigated and new insights were provided.</p>}, journal={Nano-Micro Letters}, author={Li, Yang and Yang, Wang and Yang, Wu and Wang, Ziqi and Rong, Jianhua and Wang, Guoxiu and Xu, Chengjun and Kang, Feiyu and Dong, Liubing}, year={2021}, month={Mar.}, pages={95} }