Transition-metal chalcogenide nanostructures provide a unique material platform to engineer next-generation energy storage devices such as lithium-ion, sodium-ion, and potassium-ion batteries and flexible supercapacitors. The transition-metal chalcogenide nanocrystals and thin films have enhanced electroactive sites for redox reactions and hierarchical flexibility of structure and electronic properties in the multinary compositions. They also consist of more earth-abundant elements. These properties make them attractive and more viable new electrode materials for energy storage devices compared to the traditional materials. This review highlights the recent advances in chalcogenide-based electrodes for batteries and flexible supercapacitors. The viability and structure–property relation of these materials are explored. The use of various chalcogenide nanocrystals supported on carbonaceous substrates, two-dimensional transition metal chalcogenides, and novel MXene-based chalcogenide heterostructures as electrode materials to improve the electrochemical performance of lithium-ion batteries is discussed. The sodium-ion and potassium-ion batteries offer a more viable alternative to lithium-ion technology as they consist of readily available source materials. Application of various transition metal chalcogenides such as MoS₂, MoSe₂, VS₂, and SnS_x, composite materials, and heterojunction bimetallic nanosheets composed of multi-metals as electrodes to enhance the long-term cycling stability, rate capability, and structural strength to counteract the large volume expansion during the ion intercalation/deintercalation processes is highlighted. The promising performances of layered chalcogenides and various chalcogenide nanowire compositions as electrodes for flexible supercapacitors are also discussed in detail. The review also details the progress made in new chalcogenide nanostructures and layered mesostructures for energy storage applications.

Cu₂FeSnS₄ (CFTS) nanocrystals with tunable crystal phase have been synthesized using a solution-based method. As-synthesized CFTS nanocrystals in the shape of oblate spheroid and triangular plate with band gaps of 1.54 ± 0.04 and 1.46 ± 0.03 eV, respectively, appear attractive as a low-cost substitute for thin film solar cells.

Frequency and magnetic field dependent dielectric measurements have been performed on epitaxial thin films of the double perovskite ${\mathrm{La}}_2\mathrm{Ni}\mathrm{Mn}{\mathrm{O}}_6$ , revealing a dielectric relaxation and magnetodielectric effect. The films are grown on Nb-doped and $\mathrm{Sr}\mathrm{Ru}{\mathrm{O}}_3$ -coated $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ substrates using the pulsed laser deposition technique. While a rapid dielectric relaxation is observed at $\sim 300\mathrm{K}$ , the relaxation rate increases dramatically at lower temperatures. Below the Curie temperature of ${\mathrm{La}}_2\mathrm{Ni}\mathrm{Mn}{\mathrm{O}}_6$ , the dielectric constant increases in a magnetic field for a range of temperature. This temperature range depends on magnetic field and measurement frequency. The results are explained by the influence of a magnetic field on the dipolar relaxation.