Search Results (5)

K–Se batteries offer high energy density and cost-effectiveness, making them promising candidates for energy storage systems. However, their practical applications are hindered by Se aggregation, sluggish ion diffusion, and significant volumetric expansion. To address these challenges, monodisperse hierarchical N-doped carbon microspheres (NCHS) with uniformly sized pores were synthesized as cathode hosts. The flower-like microstructure, formed by the assembly of two-dimensional building blocks, mitigated Se aggregation and facilitated uniform distribution within the pores, enhancing Se utilization. Nitrogen doping, introduced during synthesis, strengthened chemical bonding between selenium and the carbon host, suppressed side reactions, and accelerated reaction kinetics. These synergistic effects enabled efficient ion transport, improved electrolyte accessibility, and enhanced redox reactions. Additionally, the uniform particle and pore sizes of NCHS effectively mitigated volumetric expansion and surface accumulation, ensuring long-term cycling stability and superior electrochemical performance. Se-loaded NCHS (Se@NCHS) exhibited a high discharge capacity of 199.4 mA h g⁻¹ at 0.5 C after 500 cycles with 70.4% capacity retention and achieved 188 mA h g⁻¹ at 3.0 C, outperforming conventional carbon hosts such as Super P. This study highlights the significance of structural and chemical modifications in optimizing cathode materials and offers valuable insights for developing high-performance energy storage systems. Full article

The constantly growing demand for renewable electrical energy keeps the continuation of battery-related research imperative. In spite of significant progress made in the development of Na- and K-ion systems, Li-ion batteries (LIBs) still prevail in the fields of portative devices and electric or hybrid vehicles. Since the amount of lithium on our planet is significantly limited, studies dedicated to the search for and development of novel materials, which would make LIBs more efficient in terms of their specific characteristics and life lengths, are necessary. Investigations of less industry-related systems are also important, as they provide general knowledge which helps in understanding directions and strategies for the improvement of applied materials. The current paper represents a comprehensive study of cubic Li₂Fe_1−xCo_xSeO compounds with an anti-perovskite structure. These solid solutions demonstrate both cationic and anionic electrochemical activity in lithium cells while being applied as cathodes. Cobalt cations remain inactive; however, their amount in the structure defines if the Se⁰/Se²⁻ or Fe³⁺/Fe²⁺ redox couple dominates the charge compensation mechanism upon (de)lithiation. Apart from that, cobalt affects the structural stability of the materials during cycling. These effects were evaluated by means of operando XRD and XAS techniques. The outcomes can be useful for both fundamental and practice-relevant research. Full article

Recently, potassium-ion batteries (KIBs) have attracted significant interest due to a number of factors, including the growing demand for energy and limited lithium resources. However, their practical use is hampered by poor cycling stability due to the large size of K⁺. Therefore, it is critical to develop a structural design that effectively suppresses large volume changes. This study presents a simple method of using a salt template to fabricate porous microspheres (p-MoSe₂@C MS) of MoSe₂ and a carbon matrix as anode materials in KIBs. These microspheres have a distinct porous design, with uniformly distributed MoSe₂ nanocrystals embedded in the carbon matrix to prevent MoSe₂ overgrowth due to material diffusion during heat treatment. The manufacturing process combined one-step spray drying with recyclable NaCl as a hard template. Through a two-step thermal process under an inert atmosphere, the initial dextrin, NaCl, and Mo salt microspheres were converted into a p-MoSe₂@N MS composite. The carbon structure derived from the dextrin maintained the shape of the microspheres when NaCl was removed, ensuring no overgrowth of MoSe₂. This well-designed porous structure improves the interaction with the electrolyte, facilitating the transport of ions and electrons and reducing the K⁺ diffusion distances. In addition, the porous carbon structure accommodates large volume changes during cycling and maintains its structural strength. As a result, p-MoSe₂@C MS composite exhibits superior electrochemical properties, with remarkable capacity, long-term cycling stability (193 mA h g⁻¹ after 500 cycles at 2.0 A g⁻¹), and rate capability. Full article

Transition metal organic framework materials and their selenides are considered to be one of the most promising cathode materials for nickel-zinc (denoted as Ni-Zn) batteries due to their low cost, environmental friendliness, and controllable microstructure. Yet, their low capacity and poor cycling performance severely restricts their further development. Herein, we developed a simple one-pot hydrothermal process to directly synthesize NiSe₂ (denotes as NiSe₂-X based on the molar amount of SeO₂ added) stacked layered sheets. Benefiting from the peculiar architectures, the fabricated NiSe₂−1//Zn battery based on NiSe₂ and the Zn plate exhibits a high specific capacity of 231.6 mAh g⁻¹ at 1 A g⁻¹, and excellent rate performance (162.8 mAh g⁻¹ at 10 A g⁻¹). In addition, the NiSe₂//Zn battery also presents a satisfactory cycle life at the high current density of 8 A g⁻¹ (almost no decay compared to the initial specific capacity after 1000 cycles). Additionally, the battery device also exhibits a satisfactory energy density of 343.2 Wh kg⁻¹ and a peak power density of 11.7 kW kg⁻¹. This work provides a simple attempt to design a high-performance layered cathode material for aqueous Ni-Zn batteries. Full article

The use of chalcogenide elements, such as sulfur (S) and selenium (Se), as cathode materials in rechargeable lithium (Li) and sodium (Na) batteries has been extensively investigated. Similar to Li and Na systems, rechargeable potassium–sulfur (K–S) and potassium–selenium (K–Se) batteries have recently attracted substantial interest because of the abundance of K and low associated costs. However, K–S and K–Se battery technologies are in their infancy because K possesses overactive chemical properties compared to Li and Na and the electrochemical mechanisms of such batteries are not fully understood. This paper summarizes current research trends and challenges with regard to K–S and K–Se batteries and reviews the associated fundamental science, key technological developments, and scientific challenges to evaluate the potential use of these batteries and finally determine effective pathways for their practical development. Full article