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Dissolution of intermediate sodium polysulfides (Na2S x ; 4≤x≤8) is a crucial obstacle for the development of room-temperature sodium-sulfur (Na–S) batteries. One promising strategy to avoid this issue is to load short-chain sulfur (S2–4), which could prohibit the generation of soluble polysulfides during the sodiation process. Herein, unlike in the previous reported cases where short-chain sulfur was stored by confinement within a small-pore-size (≤0.5 nm) carbon host, we report a new strategy to generate short-chain sulfur in larger pores (>0.5 nm) by the synergistic catalytic effect of CoS2 and appropriate pore size. Based on density functional theory calculations, we predict that CoS2 can serve as a catalyst to weaken the S–S bond in the S8 ring structure, facilitating the formation of short-chain sulfur molecules. By experimentally tuning the pore size of the CoS2-based hosts and comparing their performances as cathodes in Na–S and Li–S batteries, we conclude that such a catalytic effect depends on the proximity of sulfur to CoS2. This avoids the generation of soluble polysulfides and results in superior electrochemical properties of the composite materials introduced here for Na–S batteries. As a result, the optimized CoS2/N-doped carbon/S electrode showed excellent electrochemical performance with high reversible specific capacities of 488 mA h g–1 (962 mA h g(s) –1) after 100 cycles (0.1 A g–1) and 403 mA h g–1 after 1000 cycles (1 A g–1) with a superior rate performance (262 mA h g–1 at 5.0 A g–1).

The gradual depletion of global fossil energy and environmental pollution make the development of hydrogen energy imminent. Two-dimensional g-C3N4 (CN) based heterostructures have attracted considerable research interest in photocatalytic H2...

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Transition metal oxides with spinel AB2O4 phases are deemed as potential anode materials for lithium-ion batteries (LIBs), attributing to high specific capacities, low cost, and environmental friendliness, but the pulverization problem induced by the volume changes upon lithiation/delithiation greatly restricts their practical applications. To overcome this problem by nanostructure engineering, we herein successfully design and fabricate one-dimensional (1D) nanotubes consisted of interconnected MnCo2O4 nanoparticles via the convenient electrospinning process and the following heating method. As an anode for LIBs, the as-prepared 1D MnCo2O4 nanotubes demonstrate superior lithium storage properties, showing a high specific capacity (701.4 mA h g–1 at 500 mA g–1 even after going through 320 cycles) and a high-rate performance (400.4 mA h g–1 at 1 A g–1). The unique 1D hollow tubular nanoarchitecture assembled from interconnected nanoparticles can provide richer active sites and shorten the lithium diffusion length, as well as mitigate the pulverization issue caused by volume changes.

TiNb 2 O 7 (TNO) has been extensively investigated as a promising energy storage material due to its superior structural stability, excellent electrochemical properties, and environmental benignancy. However, poor electrical/ionic conductivity restricts the practical application of TNO. Herein, phenolic resin spheres (PRs) are used as sacrificial templates to fabricate hollow-structured TNO nanospheres assembled from secondary nanoparticles, which are further coated with polydopamine to fabricate N-doped carboncoated hollow TNO (HTNO@N-C) nanospheres. The HTNO@ N-C nanospheres with an average diameter of ∼600 nm consisted of an inner cavity and a functional shell. The unique inner cavity provides a buffer space to relieve the volume expansion upon the lithiation process, thus ensuring excellent cycle performance. The porous TNO shell assembled by secondary interconnected nanoparticles provides extra channels to accelerate the diffusion of Li + into the inner active sites. The coated N-doped carbon layer can increase the electronic conductivity, which is beneficial to enhance Li + ions/electrons transfer to improve rate performance. Consequently, as an anode for lithium-ion batteries (LIBs), HTNO@N-C exhibits a high reversible capacity of 278.3 mAh/g at 1C, with a capacity retention of 78.0% (217.1 mAh/g) after 1000 cycles. Even when cycled at 10C and 20C, high reversible capacities of 138.0 and 100.9 mAh/g can be obtained. Moreover, HTNO@N-C electrode demonstrates excellent long-term cycling stability, delivering a reversible capacity of 116.2 mAh/g after 5000 cycles at 5C, which endows HTNO@N-C with great potential as a candidate anode for high-efficiency LIBs. More importantly, this strategy can be generally applied for the fabrication of various unique hollow structures for energy-related applications.

Titanium dioxide (TiO2) as a promising anode material for alkaline ion batteries exhibits superior structure stability upon ion insertion/extraction and excellent cycling/rate capabilities, but which still suffers from the low...

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