Phase-Dependent Energy Storage Performance of the Ni_xSe_y Polymorphs for Supercapacitor-Battery Hybrid Devices

Abstract

Transition-metal chalcogenides have emerged as a promising class of materials for energy storage applications due to their earth abundance, high theoretical capacity, and high electrical conductivity. Herein, we introduce a facile and one-pot electrodeposition method to prepare high-performance nickel selenide Ni x Se y (0.5 ≤ x/y ≤ 1.5) nanostructures (specific capacity = 180.3 mA h g–1 at 1 A g–1). The as-synthesized nickel selenide (NS) nanostructure is however converted to other polymorphs of nickel selenide including orthorhombic NiSe2, trigonal Ni3Se2, hexagonal NiSe, and orthorhombic Ni6Se5 over cycling. Interestingly, NiSe2 and Ni3Se2 polymorphs that display a more metallic character and superior energy storage performance are the predominant phases after a few hundred cycles. We fabricated a hybrid device using activated carbon (AC) as a supercapacitor-type negative electrode and NS as a high-rate battery-type positive electrode (AC||NS). This hybrid device provides a high specific energy of 71 W h kg–1, an excellent specific power of up to 31 400 W kg–1, and exceptional cycling stability (80% retention of the initial capacity after 20 000 cycles). The higher energy storage performance of the device is a result of the development of high-performance NiSe2 and Ni3Se2 polymorphs. Moreover, the reduction of the critical dimension of the NS particles to the nanoscale partially induces an extrinsic pseudocapacitive behavior that improves the rate capability and durability of the device. We also explored the origin of the superior energy storage performance of the NS polymorphs using density functional theory calculations in terms of the computed density of states around the Fermi level, electrical conductivity, and quantum capacitance that follows the trend NiSe2 > Ni3Se2 > NiSe > Ni6Se5. The present study thus provides an appealing approach for tailoring the phase composition of NS as an alternative to the commonly used templated synthesis methods.

Facile Synthesis of NiFe-LDH/CB/S Nanocomposite Electrode for Sustainable Hybrid Supercapacitors

“…By analyzing this junction point, we can gain valuable insights regarding the overall resistance characteristics of the electrodes, taking into account both the electrolyte and substrate contributions. In addition, the Warburg diffusion resistance is related to the straight line. , Figures i and S2 show the Nyquist plots and equivalent circuit diagram of three electrodes. The impedance data of the corresponding samples can be found in Table S1.…”

“…In addition, the Warburg diffusion resistance is related to the straight line. 38,61 Figures 3i and S2 show the Nyquist plots and equivalent circuit diagram of three electrodes. The impedance data of the corresponding samples can be found in Table S1.…”

Phase engineering of iron group transition metal selenides for water splitting

“…Compared with the phase engineering of CoSe 2 in lithium–oxygen batteries and Zn–air batteries, the phase engineering of Ni selenide also has excellent performance in supercapacitors. For example, Nazari et al 77 introduced a facile and one-pot electrodeposition method to prepare high-performance nickel selenide Ni x Se y (0.5 ≤ x / y ≤ 1.5) nanostructures (specific capacity = 180.3 mA h g −1 at 1 A g −1 ) including orthorhombic NiSe 2 , trigonal Ni 3 Se 2 , hexagonal NiSe, and orthorhombic Ni 6 Se 5 (Fig. 7g).…”

“…Copyright 2022 American Chemical Society. (h) Schematic illustration of the Fe-assisted cubic-to-orthohombic phase transition in CoSe 2 ; (i) CV curves of bare, CoSe 2 , C1F1 and FeSe 2 modified GCEs at a scan rate of 0.1 V s À1 with and without 200 mM 2,4-DNT in 0.1 M PBS (pH = 8.0); (j) CV curves of 200 mM of 2,4-DNT on C1F1 GCE with different scan rates (0.02-0.2 V s À1 ) 77. Copyright 2022 Elsevier B.V. All rights reserved.…”

2D-Ti3C2Tx MXene-supported Cu2S nanoflakes for supercapacitors and electrocatalytic oxygen evolution reaction

“…These types of devices are termed supercapattery (supercapacitor + battery). 3,10 Here, the supercapacitive material provides the high power density and battery-type material is responsible for attaining high energy density. These hybrid systems behave like a rechargeable battery, having high power and energy density, as well as long cycle life.…”