Scientists have made breakthroughs in lithium-ion batteries and the batteries may become smaller!

How light and thinner are consumer electronics such as mobile phones and laptops, and how electric cars can have longer mileage in limited car body space .... as demand for energy storage grows. The performance of secondary batteries has also been put forward with higher and higher requirements. Nanotechnology can make batteries "lighter" and "faster," but due to the low density of nanomaterials, "smaller" has become a problem for scientific researchers in the field of energy storage.

The "Sulfur Template Method" was proposed by the research team of Professor Yangquanhong of Tianjin University's Institute of Chemical Engineering and winner of the National Outstanding Youth Science Foundation. Through the design of high-volume energy density lithium-ion battery negative electrode materials, graphene was finally completed. "Tailor clothing", Make it possible for lithium-ion batteries to be "smaller". The result was published online on January 26 on "NatureComunicaTIons."

As the most widely used secondary battery, lithium-ion batteries have a high energy density. Non-carbon materials such as tin and Silicon are expected to replace commercial graphite as a new generation of negative electrode materials, greatly increasing the mass energy density(Whkg-1) of lithium ion batteries, but its huge volume expansion seriously limits its volumetric performance. Advantage. The carbon cage structure constructed by carbon nanomaterials is considered to be the main means to solve the problem of large volume expansion when non-carbon negative electrode materials are embedded in lithium; However, in the construction process of carbon buffer network, too much reserved space is often introduced, resulting in a significant reduction in the density of electrode materials, which limits the development of negative mass performance of lithium ion batteries. Therefore, the precise customization of carbon cage structure is not only an important academic problem, but also the only way for the industrialization of new high-performance negative electrode materials.

Professor Yangquanhong's research team has made breakthroughs in the design of high-volume energy density lithium ion battery negative electrode materials in collaboration with Tsinghua University, the National Nano Center, and the National Materials Research Institute of Japan. Based on graphene interface assembly, the research team has invented a compact porous carbon cage. Accurately customized sulfur template technology. In the process of constructing a dense graphene network using capillary evaporation technology, they introduced sulfur as a flowable volume template and customized graphene carbon coats for non-carbon-active particles. By modulating the use of sulfur templates, the three-dimensional graphene carbon cage structure can be accurately regulated to achieve a "fit" envelope of the non-carbon active particle size, thus effectively cushioning the huge volume expansion of lithium embedded in non-carbon active particles. As a negative electrode of lithium-ion battery, it shows excellent volumetric performance.

The sulfur template method is proposed in the three-dimensional graphene dense network, cleverly using the characteristics of sulfur as "Transformers", amorphous, and easy removal. The close coating of non-carbon active particles such as tin dioxide nanoparticles is realized inside the carbon cage structure. Compared with the traditional "shape" template, the biggest advantage of the sulfur template is that it can play the role of a plastic volume template, so that the compact graphene cage structure can provide suitable reserved space with precise and controllable dimensions. The "tailor" for active tin dioxide was finally completed. This carbon-non-carbon composite electrode material with suitable reserved space and high density can contribute extremely high volume-specific capacity, thereby greatly increasing the volumetric energy density of lithium ion batteries and making lithium ion batteries smaller. The design idea of this kind of "tailor clothes" can be extended to the construction strategy of the next generation high-energy lithium-ion battery and lithium-sulfur battery, lithium air battery and other electrode materials.

Professor Yangquanhong's research team has made a series of important advances in the field of compact energy storage that emphasizes device volumetric performance in recent years. It has invented the capillary evaporation densification strategy of graphene gel and solved the high density of carbon materials and porosity. The bottleneck problem of "fish and bear Palm can not be obtained at the same time", High density porous carbon materials; In pursuit of the small volume and high capacity of energy storage devices, the design principles of high-volume energy density energy storage devices are put forward from five aspects: strategy, method, material, electrode, and device. In the end, high-volume energy storage materials, electrodes, and devices were constructed from supercapacitors, sodium ion capacitors, lithium sulfur batteries, and lithium air batteries to lithium ion batteries, laying the foundation for the practical application of carbon nanomaterials. The application of new electrochemical energy storage devices based on carbon nanomaterials is advanced.

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