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To overcome the structural failure of Manganese-based Prussian blue analogue (Mn-HCF) as a cathode material of sodium ion batteries caused by Mn ion dissolution induced by Jahn–Teller effect, we coated Mn-HCF with iron-based Prussian blue (Fe-HCF) to prepare the core–shell Mn-HCF@Fe-HCF cathode material for sodium ion batteries through co-precipitation method. The research results indicate that this structure effectively blocks the direct contact between Mn-HCF and electrolyte, thereby minimizing the dissolution of Mn 3 + in the electrolyte and significantly improving the cycling stability and rate performance. The discharge capacity of this material at a current density of 0.1 C (14 mA g − 1) is 129.7 mAh g − 1 . It still has a capacity of 87.4 mAh g − 1 at a current density of 2 C (280 mA g − 1) , and still has a capacity retention rate of 84.3% (91 mAh g − 1) after 100 cycles at a current density of 0.5 C (70 mA g − 1). Compared with the capacity retention rate of 51.5% of Mn-HCF 100 cycles before coating, the cycle stability of Mn-HCF@Fe-HCF is greatly improved. The Mn-HCF@Fe-HCF material was successfully prepared through a simple coprecipitation method. When applied in sodium-ion batteries, the Mn-HCF@Fe-HCF exhibited a remarkable cycle stability of 129.7 mAh g–1 at 0.1 C, along with an impressive rate performance of 104.2 mAh g–1 at 1 C. [ABSTRACT FROM AUTHOR]

Tin-based are considered ideal anode materials for sodium ion batteries (SIBs) due to their high-theoretical capacity and low cost, among which tin disulfide (SnS2) has been the most widely studied. Here, hierarchical flower SnS2 were prepared by a simple one-step solvothermal method, and SnS2@C was synthesized by carbonization after stirring with dopamine. It is precisely because of this special morphology that the material itself has a larger buffer space, which effectively improves the volume expansion problem, and the composite with carbon materials also greatly improves the poor electrical conductivity of the sulfide itself, serious volume expansion, polysulfide dissolution and other problems. When applied in SIBs anode, hierarchical flower SnS2 structure showed excellent specific capacity of 180.8 mA h g−1 after 500 cycles at a high current density of 5 A g−1. This work provides a new route for realizing high-capacity and long-cycle SnS2@C composite in SIBs anode. [ABSTRACT FROM AUTHOR]

Uniformly distributed NiCo2S4 nanoparticles on hollow carbon spheres were prepared by carbonisation and in-situ vulcanisation methods as a positive electrode host for lithium–sulphur batteries. Among them, carbon hollow spheres can provide a huge internal cavity, which prevents volume expansion during the charge and discharge process. At the same time, the physically limit the dissolution of polysulfides in the electrolyte and can also provide high conductivity. The NiCo2S4 nanoparticles on the surface can establish a specific polar environment for charge and discharge and can interact with polysulfides to mitigate the loss of active materials through chemical adsorption. Under the synergistic effect of NiCo2S4 and carbon hollow spheres, the electrode with a special structure of NiCo2S4/carbon hollow spheres as sulfur host exhibits excellent long cycle performance. At a current density of 335 mA g−1, it still has a high discharge specific capacity of 526 mAh g−1 after 500 cycles. [ABSTRACT FROM AUTHOR]