An excellent full sodium-ion capacitor derived from a single Ti-based metal-organic framework

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2018, Vol.6 (48), p.2486-24868
• Main Authors: Chen, Hao, Dai, Chunlong, Li, Yanan, Zhan, Renming, Wang, Min-Qiang, Guo, Bingshu, Zhang, Youquan, Liu, Heng, Xu, Maowen, Bao, Shu-juan
• Format: Article
• Language: English
• Subjects: Anodes; Batteries; Capacitors; Carbon; Cathodes; Cycles; Density; Electrochemistry; Energy storage; Etching; Flux density; Kinetic energy; Metal-organic frameworks; Metals; Nanoparticles; Sodium; Specific capacity; Titanium
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c8ta09072f

Hybrid ion capacitors, especially sodium ion capacitors (SICs), have recently attracted enormous attention due to their combined merits of high energy density from the battery-type anode and high power density from the capacitor-type cathode. However, achieving high-performance SICs to overcome the sluggish kinetic energy storage feature and inferior cycling stability of the battery-type anode remains a challenge. In this work, N-doped porous carbon embedded with ultrasmall titanium oxynitride nanoparticles (TiO x N y /C) was developed from metal-organic frameworks (MOFs). As the SIC anode, the as-designed TiO x N y /C exhibited a high reversible capacity (275 mA h g −1 at 50 mA g −1 ), ultrahigh rate capability, and superior cycling performance, which is attributed to the effective synergy between the ultrasmall TiO x N y nanoparticles and N-doped porous carbon. Furthermore, using a "two-for-one" strategy, N-doped hierarchical porous carbon (NHPC) with high surface area was prepared from TiO x N y /C by HF etching and displayed high specific capacity and rate capability when used as a SIC cathode. Considering the excellent electrochemical performances of both the anode and cathode, the as-assembled TiO x N y /C//NHPC SIC delivered a high energy density (80 W h kg −1 ) and high power density (4000 W kg −1 ). Hybrid ion capacitors, especially sodium ion capacitors (SICs), have recently attracted enormous attention due to their combined merits of high energy density from the battery-type anode and high power density from the capacitor-type cathode.