Lithium-sulfur battery structure catalysis, conductive interface construction

Lithium-sulfur battery (li-s) has a higher theoretical energy density (2500wh/kg) than traditional lithium-ion batteries, and is expected to become the most promising candidate system for energy storage applications (including large-scale smart grids, electric vehicles and mobile electronic devices) one. In recent years, in order to realize the commercialization of lithium-sulfur batteries, many strategies have been proposed, such as the development of new cathode composite materials, intermediate layer or separator decoration, multifunctional adhesives, and electrolyte additives. The introduction of the polar host material can further enhance the chemical adsorption of lithium polysulfide, thereby improving the cycle stability of the battery. However, the inherent low conductivity of non-carbon polar bodies often leads to low sulfur utilization, especially when sulfur is unevenly distributed under high load. Therefore, it is necessary to explore a more conductive polar host material and its full contact with the carbon skeleton. Recently, Li Qilin, a researcher at the Shanghai Institute of Ceramics, Chinese Academy of Sciences, and Yang Minghui, a researcher at the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, jointly designed a sulfur host material with a catalyst-carbon catalyst sandwich structure and a compact two-dimensional catalytic conductive interface. High stability of lithium-sulfur battery. Related results were published in the international academic journal Angewandte Chemie (document 2020doi.org/10. 1002/Ani. 202004048). The d-orbitals of metal nitride overlap each other, and its conductivity is equivalent to that of metal. They are ideal polar materials for lithium polysulfide adsorption and can promote charge transfer and potential electrocatalysis. However, the method of recombination of metal nitrides in the carbon framework is limited. Usually there is only point-to-point or point-to-surface contact between the nanoparticle nitride and the carbon framework, the contact area is limited, and the charge transfer ability is limited. Therefore, in the polar host particles ( It is still a challenge to establish a continuous interface with sufficient contact (face-to-face contact) between (or site) and the carbon skeleton. In addition, in the loose sulfur host framework, vacancies and non-polar volume spaces usually account for a larger proportion. The point contact between the discrete catalyst nanocrystal domains and the conductive substrate cannot reduce the proportion of this non-catalytically active space, which will hinder the development of high-load lithium-sulfur batteries. Reasonable anode design and microstructure combination can minimize the volume of no-load and non-polar batteries, which is expected to promote the development of compact lithium-sulfur batteries. On this basis, the research team proposed a mon-c-mon'sandwich' main structure with a continuous two-dimensional catalytic and conductive interface with catalytic and electron transfer functions as the main material of sulfur cathode for lithium-sulfur batteries. This three-layer structure exists in a single nanoparticle along the thickness direction, which promotes the strong conformal adsorption and efficient conversion of S/li2sx on the double-sided outer nitride polar surface, and the high-flux electron transfer of the middle carbon layer. These two-dimensional 'sandwich' structural units can further self-assemble into an ordered three-dimensional texture, which further strengthens the interconnection between the conductive network and the catalytic network. Even if the specific surface area of u200bu200bthe host framework is low (97 m2/g), the maximum exposure of the adsorption/catalytic plane from Monday to Friday under high s load (75.7 wt%) and 1C (1Cu003d1672ma/g), the electrode can still Stable cycles for at least 1000 times. Even at a high 4C, the capacity decay rate per cycle is only 0.033%, and the specific capacity can be maintained at 515mah/g. When the sulfur content increases to 3.4mg/cm~2, three layers of dense sulfur The carrier still exhibits good conductivity, and its capacity remains at 604mah/g after 500 cycles. The coordinated working mode of the catalytic and conductive functions ensures the uniform deposition of S/li2sx and avoids the thickening and deactivation of the electrode (electrode passivation) after high-speed and long-term cycles. The reported chelating amination method provides a guarantee for the orderly separation and surface contact of the C and mon phases, and also provides a new synthetic method for the preparation of two-dimensional nitrides. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Power lithium battery manufacturers explain the current market situation behind the huge demand for shared lithium batteries