Merging of Kirkendall Growth and Ostwald Ripening: CuO@MnO2 Core-shell Architectures for Asymmetric Supercapacitors

Abstract

Fabricating hierarchical core-shell nanostructures is currently the subject of intensive research in the electrochemical field owing to the hopes it raises for making efficient electrodes for high-performance supercapacitors. Here, we develop a simple and cost-effective approach to prepare CuO@MnO2 core-shell nanostructures without any surfactants and report their applications as electrodes for supercapacitors. An asymmetric supercapacitor with CuO@MnO2 core-shell nanostructure as the positive electrode and activated microwave exfoliated graphite oxide (MEGO) as the negative electrode yields an energy density of 22.1 Wh kg−1 and a maximum power density of 85.6 kW kg−1; the device shows a long-term cycling stability which retains 101.5% of its initial capacitance even after 10000 cycles. Such a facile strategy to fabricate the hierarchical CuO@MnO2 core-shell nanostructure with significantly improved functionalities opens up a novel avenue to design electrode materials on demand for high-performance supercapacitor applications.

High‐Performance Fiber‐Shaped All‐Solid‐State Asymmetric Supercapacitors Based on Ultrathin MnO2 Nanosheet/Carbon Fiber Cathodes for Wearable Electronics

“…The superior electrochemical performance of the ASCs is further confi rmed by galvanostatic charge-discharge measurement ( Figure 4 c and Figure S16b, Supporting Information). The specifi c capacitance of the fi ber-shaped all-solid-state ASCs reaches 87.1 F g −1 at a current density of 1.25 A g −1 , which is much higher than recently reported value for other ASCs like MnO 2 -electrochemical reduced graphene oxide (ERGO)// CNT-ERGO (69.4 F g −1 at 0.5 A g −1 ), [ 47 ] CuO@MnO 2 core-shell nanostructures// microwave exfoliated graphene oxide (MEGO) (49.2 F g −1 at 0.25 A g −1 ), [ 24 ] and so on. [ 48 ] To examine the fl exibility and mechanical stability of as-fabricated fi ber-shaped ASCs, CV measurement was carried out at 100 mV s −1 under different bending states (Figure 4 d).…”

“…The Mn 2p XPS spectrum (Figure 1 c) shows two peaks at the binding energy of 642.1 and 653.9 eV, corresponding to Mn 2p 3/2 and Mn 2p 1/2 with a spin-energy separation of 11.8 eV, which are in accordance with the previous reports on MnO 2 . [23][24][25] The separation value of the binding energy (Δ E b ) between two Mn 3s peaks allows us to further estimate the average oxidation state of Mn in MnO 2 .…”

A facile one-step approach to hierarchically assembled core–shell-like MnO2@MnO2 nanoarchitectures on carbon fibers: An efficient and flexible electrode material to enhance energy storage

“…MnO 2 NSs with controllable shapes and sizes have been synthesized using different growth methods [32][33][34]. In particular, three-dimensional (3D) flower shaped and hierarchical core-shell-like MnO 2 NSs synthesized by assembling 1D or 2D building blocks (such as nanosheets, nanoparticles, and nanowires) have shown significant enhancement in energy storage properties [35][36][37][38]. Because of their high specific surface area, high porosity, and 3D structures, hierarchical MnO 2 pseudocapacitive materials provide additional electroactive sites with shorter diffusion pathways for ions and electrons.…”

Binder free 2D aligned efficient MnO2 micro flowers as stable electrodes for symmetric supercapacitor applications

“…80-1098. 6,52 The peak broadening or poor intensity may be due to the small particle size and distorted structure of the deposited thin lms. Apart from these peaks, we observed some extra peaks at 43 , 51 and 75 due to the exposed stainless steel mesh substrate, which was in good agreement with the XRD pattern of bare SSM substrate prior to MnO 2 deposition (Fig.…”

“…3,6 Based on the charge storage mechanism, supercapacitors are classied into electrical double layer capacitors (EDLCs) and redox supercapacitors (pseudocapacitors). [7][8][9][10] In EDLCs, the capacitance comes from the charge separation at electrode/electrolyte interfaces 7,9 and in the case of pseudocapacitors, the capacitance arises from faradaic reaction at the electrode/electrolyte surface.…”