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Chinese energy storage network: with the development of society and technology, the demand for electrochemical energy storage technology is increasing, and researchers are looking for the next generation of batteries with higher energy than energy.
Lithium sulfur batteries with sulfur as the positive active material, based on the reversible electrochemical reaction between lithium sulfur and to achieve the energy storage and release, its theoretical quality than energy can reach 2600 Wh/kg, is three to five times the current lithium ion battery, is expected to be applied in the power battery, portable electronic products and other fields, but the internal disulfide through effects caused by circulation of the question of short life will limit its practical application in the future.
Recently, the Chinese academy of sciences suzhou institute of nanotechnology and nano-bionics research institute for the study of the anode materials of lithium - sulfur batteries.
The researchers showed a new strategy that is different from conventional sulfur positive material packages.
The conventional coating strategy is to prepare a coating layer outside the particles of the sulfur positive material, then prepare the material into a positive electrode and then assemble it into a battery with the electrolyte.
Conventional coating strategy is a formidable paradox: if material particles has been covered before assembling battery have perfect cladding layer, the electrolyte will not spread into the inside material, which can lead to internal sulphur cannot participate in charging and discharging process;
If the material is not covered by the perfect coating, the polysulfide in the middle product of the charging and discharging process will be diffused from the positive electrode material, resulting in the shuttle effect.
In this new work, the researchers in advance on the carbon/sulfur compound particles grow a layer of imperfect pre cladding layer containing hole (complete) during the process of material preparation, after the material preparation and into the positive with contains special additive to the electrolyte of the assembled into the cell.
While the electrolyte is impregnated with carbon/sulfur particles, the additive will react with the pre-cladding layer to form a dense coating on the outside of the particle.
This method avoids the disadvantages of conventional means, which can not only realize the infiltration of electrolyte and materials, but also restrict the diffusion of polysulfide.
The results show that the coulomb efficiency and cycle life of lithium-sulphur batteries with this new coating strategy are significantly improved.
The assembled battery showed excellent circulation stability under the condition of high discharge ratio, and the current density of 1C was circulated 1000 times, and the capacity attenuation rate of single cycle was 0.03%.
The results have been published in Nature Communications (8, 479, 2017).
The work has been supported by the strategic advanced science and technology research project of the Chinese academy of sciences, the key research and development plan of the ministry of science and technology, and the national natural science foundation.