Simultaneous realization of high sulfur utilization and lithium dendrite-free via dual-effect kinetic regulation strategy toward lithium-sulfur batteries

With the high theoretical specific capacity and energy density,lithium-sulfur batteries(LSBs)have been intensively studied as promising candidates for energy storage devices.However,LSBs are largely hindered by inferior sulfur utilization and uncontrollable dendritic growth.Herein,a hierarchical functionalization strategy of stepwise catalytic-adsorption-conversion for sulfur species via the synergetic of the efficiently catalytic host cathode and light multifunctional interlayer has been proposed to concurrently address the issues arising on the dual sides of the LSBs.The multi-layer SnS_(2) micro-flowers embedded into the natural three-dimensional(3D)interconnected carbonized bacterial cellulose(CBC)nanofibers are fabricated as the sulfur host that provides numerous catalytic sites for the rapid catalytic conversion of sulfur species.Moreover,the distinctive CBC-based SnO_(2)-SnS_(2) heterostructure network accompanied high conductive carbon nanofibers as the multifunctional interlayer promotes the rapid anchoringdiffusion-conversion of lithium polysulfides,Li^(+)flux redistribution,and uniform Li deposition.LSBs equipped with our strategy exhibit a high reversible capacity of 1361.5 m A h g^(-1)at 0.2 C and superior cycling stability with an ultra-low capacity fading of 0.031%per cycle in 1000 cycles at 1.5 C and 0.046%at 3 C.A favorable specific capacity of 859.5 m A h g^(-1)at 0.3 C is achieved with a high sulfur mass loading of 5.2 mg cm^(-2),highlighting the potential of practical application.The rational design in this work can provide a feasible solution for high-performance LSBs and promote the development of advanced energy storage devices.

Long-term Properties of Aeolian Sand-magnesium Oxychloride Cement Composites and Its Engineering Application

In order to prepare a new material with long-term stable performance,low cost,easy construction,and ecological environmental protection,the influence of aeolian sand on the compressive and flexural strength as well as micro morphology and phase composition of magnesium oxychloride cement(MOC)was studied.The experimental results indicate that,with the increase of content of doping sand,the compressive strength and flexural strength of MOC decrease significantly.However,when the quality ratio of aeolian sand and light burned magnesia powder is 1:8,the performance meets the actual engineering needs.Namely,the compressive strength of MOC is not less than 18 MPa,and flexural strength is not less than 4 MPa.Meanwhile,within 12 months of age,the compressive strength and flexural strength are stable.There is no obvious change in phase composition,and its main phase is still 5·1·8 phase.Microscopic appearance changes from needle-like to gel-like shape.Based on engineering applications,it is found that when the novel sand-fixing material is used in the field for one year,its macroscopic feature is not damaged,compressive strength and flexural strength are also more stable,phase composition negligibly changes,and micro morphology has also been turned into be gellike shape.These further confirm the long-term stability and weather resistance of MOC doping aeolian sand,providing theoretical and technical support for the widely application of MOC in the field of sand fixation in the future.

Long cycle performance of NC@VN/MnO cathode for AZIBs based on Mn/V relay type collaboration

Aqueous zinc ion batteries(AZIBs) have received great attention because of their non-toxicity,high safety,low cost,high abundance,and high specific power.However,their specific capacity is still low compared with lithium ion battery,and current academic research interesting has been focused on developing new cathode materials with high specific capacity.In this study,a Mn/V hybrid polymer framework is designed by a simple self-polymerization scheme.During subsequent calcination,ultrafine VN quantum dots and MnO nanoparticles are generated in situ and stably encapsulated inside N-doped carbon(NC) shells to obtain a novel hybrid cathode NC@VN/MnO for AZIBs.According to the density functional theory(DFT) calculation,the hybrids of MnO and VN can generate both interfacial effects and built-in electric fields that significantly accelerate ion and electron transport by tuning the intrinsic electronic structure,thus enhancing electrochemical performance.A synergistic strategy of composition and structural design allows the rechargeable AZIBs to achieve low-cost and excellent long-cycle performance based on a relay type collaboration at different cycling stages.Consequently,the NC@VN/MnO cathode has output a capacity of 108.3 mA h g^(-1)after 12,000 cycles at 10 A g^(-1).These results clearly and fully demonstrate the advantages of the hybrid cathode NC@VN/MnO.