Electrostatically Fabricated Three-Dimensional Magnetite and MXene Hierarchical Architecture for Advanced Lithium-Ion Capacitors

• Published in: ACS applied materials & interfaces 2020-02, Vol.12 (8), p.9226-9235
• Main Authors: Wang, Shijie, Jin, Dongdong, Bian, Ye, Wang, Rutao, Zhang, Li
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.9b20846

Conversion-type magnetite shrewdly shows abundance, nontoxicity, and high lithium storage capacity. However, either pristine magnetite or nanocomposites with two-dimensional materials cannot prevent restacking, pulverization, and poor structural homogeneity simultaneously because of a lack of universal interfacial interactions. Here, an electrostatic self-assembly strategy is uncovered between hollow Fe3O4/C microspheres (with H+-induced quasi-intrinsic positive charge) and few-layer MXenes (with intrinsic negative charge from terminating functionalities). This strategy realizes the uniform and interconnected architecture of Fe3O4/C@MXene that favors fast Li+ diffusion, easy electron/charge transfer, and suppressed pulverization. Specifically, after the long-term cycling, an undegraded specific capacity of 907 mA h g–1 remains at 0.5 A g–1. Further adoption of such superior anode in 4.0 V lithium-ion capacitors results in a high energy density of 130 W h kg–1, a maximum power density of 25,000 W kg–1, and excellent cycling stability. This work thus sheds light on a generic self-assembly process where intrinsic electrostatic interaction plays an essential role.