# Tailoring Cobalt Content in MnO x Nanowires for Superior Supercapattery Performance

## TL;DR

This paper shows that adding the right amount of cobalt to manganese oxide nanowires improves their performance in supercapattery devices.

## Contribution

The study introduces a method to tailor cobalt content in MnOx nanowires for optimized supercapattery performance.

## Key findings

- 6.63 wt% Co doping maximized specific capacitance and cycling stability in MnOx nanowires.
- High Co content caused aggregation and reduced electrochemical performance.
- The optimized Co-MnOx achieved 393.6 Wh·kg–1 energy density with 61% retention after 2200 cycles.

## Abstract

Herein, we report the urea-assisted synthesis of Co-doped
MnO
x
nanowires with cobalt contents of
5.85,
6.63, and 19.22 wt %. ICP-OES confirmed Co incorporation, while SEM,
TEM, and EDS analyses showed that low-to-moderate Co loadings preserve
the nanowire morphology with homogeneously dispersed Co species, whereas
high Co content induces aggregation. XPS revealed that 6.63 wt % Co
optimized the Mn4+/Mn3+ ratio and increased
the concentration of defect-related surface oxygen species, while
excessive Co doping promoted Mn reduction. EPR/FMR measurements confirmed
the formation of metallic Co aggregates at higher loadings. Electrochemical
testing in 2 M KOH demonstrated that Co-MnO
x
(6.63 wt %) delivered the highest specific capacitance (1468.65
F·g–1 at 1 A·g–1) and
excellent cycling stability. Moreover, a AC//Co-MnO
x
(6.63 wt %) supercapattery achieved an energy density of 393.6
Wh·kg–1 and a power density of 2928 W·kg–1 with 61% retention after 2200 cycles. The enhanced
electrochemical activity is attributed to an optimized cobalt content
that maximizes defect-related oxygen species and promotes favorable
Co–Mn electronic interactions without inducing surface saturation,
resulting in improved supercapattery performance.