Novel hierarchical CoFe2Se4@CoFe2O4 and CoFe2S4@CoFe2O4 core-shell nanoboxes electrode for high-performance electrochemical energy storage

Zn–Ni–Se@NiCo2S4 Core–Shell Architectures: A Highly Efficient Positive Electrode for Hybrid Supercapacitors

“…29,30 To deal with these issues, diverse approaches can be applied: (1) utilization of bimetallic selenides instead of monometal selenide, 31 (2) fabricating hierarchical architecture, which is favorable for the diffusion of ions and sufficient contact between electrolyte and active materials, thus enhancing the rate capability, 32 selenides with appropriate materials, including metal sulfide, which could enhance the electronic conductivity, thereby improving durability, 33 and (4) direct growth and preparation of materials on the conductive substrates (e.g., nickel foam), which can substantially improve performance as a result of its binder-free electrode design. 34 In contrast to monometal selenide, bimetallic selenides, including NiCo 2 Se 4 , 35 CoFe 2 Se 4 , 36 and NiV 2 Se 4 , 37 demonstrate richer faradaic reactions, which lead to obvious enhancement of the activities. Furthermore, bimetallic selenides also indicate superior electrochemical behavior to bimetal metal oxides because of lower bandgap during the anion-exchange process, which leads to quicker electronic transport.…”

Bucket Effect: A Metal–Organic Framework Derived High-Performance FeS2/Fe2O3@S-rGO Negative Material for Enhanced Overall Supercapacitor Capacitance

“…Supercapacitors, a promising sustainable energy storage device, have attracted immense attention among researchers for their promising applications in electric vehicles, portable consumer electronics, and state grid systems because of their high power density, low maintenance costs, and superior lifespan. − Although capacitances up to 3–5 orders of magnitude higher than physical capacitors have been achieved by supercapacitors, there is continuous demand for further increasing their capacitances to meet the growing requirement of future devices. − Because an entire supercapacitor device can be treated as two capacitors (a positive electrode and a negative electrode) in series, the overall capacitance ( C T ) can be calculated by the following eq which demonstrates how much “water” a supercapacitor can hold depends on the electrode with a smaller capacitance . Nowadays, great progress has been made in the positive electrode materials, and high specific capacitances (≥1500 F g –1 , commonly) have already been achieved by a part of Ni-/Co-based nanomaterials. − In contrast, the achievements on negative electrode materials are lagging and most of the reported research studies focus on electrochemical double-layer capacitor-based carbon materials with low specific capacitance (≤300 F g –1 , commonly). − For instance, although high capacitances of 1860 and 1759 F g –1 at 1 A g –1 are achieved by the YNi-2 and Ni-95 (nanosheet array) NSA positive electrodes, the reported YNi-2//AC and Ni-95//AC devices present unsatisfactory capacitances of 140 and 105.6 F g –1 at 1 A g –1 , respectively, limited by the weak property of the negative electrode.…”

In Situ Construction of a Heterostructured Zn–Mo–Ni–O–S Hollow Microflower for High-Performance Hybrid Supercapacitors

“…11−13 For the practical application of electrode materials for SCs, transition metal oxides/sulfides (TMOs/TMSs) have been explored due to their rich active sites, high theoretical specific capacitance, and low cost. 14 Among them, TMO shows a low conductivity and poor stability, 15,16 while transition hydroxide/ sulfide exhibits a high conductivity, but the inevitable volume expansion during the cycle process results in an inferior stability. 17 In addition, mixed TMOs/TMSs deliver a better electrochemical performance than single metal composites due to the synergistic effects of various metal centers.…”