AsianScientist (May 13, 2016) – Researchers in China are making inroads into developing more efficient lithium–sulfur batteries (LSBs). Professor Hou Yanglong’s lab from the College of Engineering at Peking University has published the results of two papers in Advanced Materials and Advanced Energy Materials.
Due to the increasing demands of energy storage in portable electronics, vehicle electrification and grid-scale stationary storage, advanced batteries with high energy density have recently attracted intensive interest.
LSBs are a promising electrochemical energy storage technology due to their high theoretical capacity, reduced cost and environmental friendliness. However, despite the significant advances of LSBs—their remarkable theoretical energy density is over five times greater than that of conventional lithium-ion batteries—its large-scale implementation is plagued by several challenges. One primary hurdle is the dissolution of polysulfide intermediate species during the process of battery discharging.
To tackle this problem, the Hou group designed a unique structure, namely, silicon/silica (Si/SiO2) cross-linked with hierarchical porous carbon spheres (Si/SiO2/C). They used this structure as a new and efficient sulfur host to prepare Si/SiO2@C-S hybrid spheres to solve the issue of polysulfide dissolution. They employed the concept of both physical and chemical adsorptions of polysulfides via the carbon and Si/SiO2 of developed hybrid spheres, respectively.
Distinct from traditional porous carbon structures, the developed hybrid spheres afford intriguing structural advantages. As a result of their multiple advantages, the developed Si/SiO2@C-S hybrid spheres show high cycling stability and can maintain high reversible capacity.
In the other paper, the group proposed a simple carbonization method to make 3D vertically aligned and interconnected carbon nanosheets (3D-VCNs) to increase performance of LSBs at low cost. 3D porous carbon nanostructures are attractive candidates for rechargeable batteries because they have great potential electrochemical applications.
The present 3D nanostructures with a very high surface area can enhance the performance of LSBs in the terms of capacity, rate ability, and cycling stability. The developed porous structure is beneficial in facilitating the easy access of electrolytes through the structure of 3D-VCNs infiltered with sulfur (3D-S-VCNs) during the cycling process.
As a consequence, the unique 3D-S-VCNs show high initial discharge capacity with excellent Coulombic efficiency, and presents a long stability up to 300 cycles.
Furthermore, the electrode bears the excellent rate capability and maintains a high reversible capacity.
The articles can be found at: Rehman et al. (2016) Rational Design of Si/SiO2@Hierarchical Porous Carbon Spheres as Efficient Polysulfide Reservoirs for High-Performance Li–S Battery.
Rehman et al. (2016) 3D Vertically Aligned and Interconnected Porous Carbon Nanosheets as Sulfur Immobilizers for High Performance Lithium-Sulfur Batteries.
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Source: Peking University; Photo: Shutterstock.
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