Issue 13, 2023

Superior cyclability of high surface area vanadium nitride in salt electrolytes

Abstract

High surface area vanadium nitrides (VNs) have been extensively studied as materials for aqueous supercapacitors due to the high initial capacitance in alkaline media at low scan rates. However, low capacitance retention and safety limit their implementation. The use of neutral aqueous salt solutions has the potential to mitigate both of these concerns, but is limited in analysis. Hence, we report on the synthesis and characterization of high surface area VN as a supercapacitor material in a wide variety of aqueous chlorides and sulfates using Mg2+, Ca2+, Na+, K+, and Li+ ions. We observe the following trend in the salt electrolytes: Mg2+ > Li+ > K+ > Na+ > Ca2+. Mg2+ systems provide the best performance at higher scan rates with areal capacitances of 294 μF cm−2 in 1 M MgSO4 over a 1.35 V operating window at 2000 mV s−1. Furthermore, VN in 1 M MgSO4 maintained a 36% capacitance retention from 2 to 2000 mV s−1 compared to 7% in 1 M KOH. Capacitance in 1 M MgSO4 and 1 M MgCl2 increased to 121% and 110% of their original values after 500 cycles and maintained capacitances of 589 and 508 μF cm−2 at 50 mV s−1 after 1000 cycles, respectively. In contrast, in 1 M KOH the capacitance decreases to 37% of its original value, reaching only 29 F g−1 at 50 mV s−1 after 1000 cycles. The superior performance of the Mg system is attributed to a reversible surface 2 e transfer pseudocapacitive mechanism between Mg2+ and VNxOy. These findings can be used to further the field of aqueous supercapacitors to build safer and more stable energy storage systems that can charge quicker compared to KOH systems.

Graphical abstract: Superior cyclability of high surface area vanadium nitride in salt electrolytes

Supplementary files

Article information

Article type
Paper
Submitted
16 noy 2022
Accepted
06 may 2023
First published
09 iyn 2023
This article is Open Access
Creative Commons BY license

Nanoscale Adv., 2023,5, 3485-3493

Superior cyclability of high surface area vanadium nitride in salt electrolytes

J. Kasten, C. Hsiao, D. Johnson and A. Djire, Nanoscale Adv., 2023, 5, 3485 DOI: 10.1039/D2NA00810F

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