Exploiting the Condensation Reactions of Acetophenone to Engineer Carbon‐Encapsulated Nb2O5 Nanocrystals for High‐Performance Li and Na Energy Storage Systems

• Published in: Advanced energy materials Vol. 9; no. 42
• Main Authors: Han, Xianying, Russo, Patrícia A., Goubard‐Bretesché, Nicolas, Patanè, Salvatore, Santangelo, Saveria, Zhang, Rui, Pinna, Nicola
• Format: Journal Article
• Language: English
• Published: 01.11.2019
• Subjects: acetophenone; hybrid supercapacitors; Li‐ion storage; Na‐ion storage; niobium oxide
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201902813

Efficient synthetic methods to produce high‐performance electrode‐active materials are crucial for developing energy storage devices for large‐scale applications, such as hybrid supercapacitors (HSCs). Here, an effective approach to obtain controllable carbon‐encapsulated T‐Nb2O5 nanocrystals (NCs) is presented, based on the solvothermal treatment of NbCl5 in acetophenone. Two separate condensation reactions of acetophenone generate an intimate and homogeneous mixture of Nb2O5 particles and 1,3,5‐triphenylbenzene (TPB), which acts as a unique carbon precursor. The electrochemical performance of the resulting composites as anode electrode materials can be tuned by varying the Nb2O5/TPB ratio. Remarkable performances are achieved for Li‐ion and Na‐ion energy storage systems at high charge–discharge rates (specific capacities of ≈90 mAh g−1 at 100 C rate for lithium and ≈125 mAh g−1 at 20 C for sodium). High energy and power densities are also achieved with Li‐ and Na‐ion HSC devices constructed by using the Nb2O5/C composites as anode and activated carbon (YPF‐50) as cathode, demonstrating the excellent electrochemical properties of the materials synthesized with this approach. A new simple two‐in‐one approach is developed to control the fabrication of carbon‐encapsulated T‐Nb2O5 nanocrystals with unique properties for electrochemical energy storage applications. The nanocomposites demonstrate remarkable specific capacities as anode electrode materials at very high charge–discharge rates, in both Li‐ion and Na‐ion devices.