673886040@qq.com
Can salt improve battery performance?
Researchers from Queen Mary University of London and the University of Cambridge, UK, and the Max Planck Institute for Solid State Research, Germany, have discovered how salt can be used to improve battery performance.
It has been found that adding salt to the inside of a super molecular sponge and then baking it at a high temperature transformed the sponge into a carbon-based structure. In this study, the researchers demonstrate that the use of materials in lithium-ion batteries not only enables the batteries to be charged-up rapidly, but also at one of the highest capacities, improving the battery performance.
By adding salt to the batteries, it reacted with the sponge that then turned it from a homogeneous mass to an intricate structure with fibres, struts, pillars and webs.
This kind of 3D hierarchically organised carbon structure has proven very difficult to grow in a laboratory but is crucial in providing unhindered ion transport to active sites in a battery.
What can these structures be used for?
The researchers have termed these intricate structures ‘nano-diatoms’ and believe they could also be used in energy storage and conversion, for example as electrocatalysts for hydrogen production.
Lead author and project leader Dr Stoyan Smoukov, from Queen Mary’s School of Engineering and Materials Science, said: “This metamorphosis only happens when we heat the compounds to 800°C and was as unexpected as hatching fire-born dragons instead of getting baked eggs in the Game of Thrones. It is very satisfying that after the initial surprise, we have also discovered how to control the transformations with chemical composition.”
Utilising nanostructures to improve battery performance
Carbon, including graphene and carbon nanotubes, is a group of the most versatile materials in nature, used in catalysis and electronics because of its conductivity and chemical and thermal stability.
3D carbon-based nanostructures with multiple levels of hierarchy can not only retain useful physical properties like good electronic conductivity, but can also have unique properties. These 3D carbon-based materials can exhibit:
- High strength per unit weight; and
- Directional pathways for fluid transport.
The super molecular sponge used in the study is also known as a metal organic framework (MOF) material, which are molecularly designed porous materials with many promising applications such as gas storage and separation.
So far, carbonising MOFs has preserved the structure of the initial particles like that of a dense carbon foam. By adding salts to these sponges and carbonising them, the researchers found a series of carbon-based materials with multiple levels of hierarchy.
Dr R Vasant Kumar, a collaborator on the study from University of Cambridge, commented: “The strategy for structuring carbon materials could be important not only in energy storage but also in energy conversion and sensing.”
