How can electronic consumer products such as mobile phones and laptops be lighter and thinner? How can electric vehicles have longer battery life in a limited body space... As people’s demand for energy storage grows, the performance of secondary batteries Raised higher and higher requirements. Nanotechnology can make batteries "lighter" and "faster", but because of the lower density of nanomaterials, "smaller" has become a problem for researchers in the field of energy storage.
The research team of the National Science Fund for Distinguished Young Scholars and Professor Yang Quanhong from the School of Chemical Engineering of Tianjin University proposed the “sulfur template methodâ€. Through the design of the anode material of high-volume energy density lithium-ion battery, the “tailor-cut†of graphene on the active particle wrapping was finally completed. It is possible to make lithium-ion batteries "smaller". The results were published online January 26 in Nature Communications (2018, 9, 402).
As the most widely used secondary battery at present, 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, which greatly improve the mass energy density (Wh kg-1) of lithium ion batteries, but its huge volume expansion severely limits its volume performance advantages. The carbon cage structure constructed by carbon nanomaterials is considered to be the main means to solve the huge volume expansion problem of lithium insertion in non-carbon anode materials. However, in the construction process of carbon buffer networks, too much reserved space is often introduced, resulting in electrode materials. The density is greatly reduced, which limits the performance of the negative electrode of the lithium ion battery. Therefore, the precise customization of the carbon cage structure is not only an important academic problem, but also the only way for the industrialization of new high-performance anode materials.
Professor Yang Quanhong and the collaborators of Tsinghua University, National Nano Center and National Institute of Materials Research have made breakthroughs in the design of anode materials for high-volume energy density lithium-ion batteries. Based on graphene interface assembly, they have invented a precise customization of dense porous carbon cages. 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 the graphene carbon outer coat for non-carbon active particles. By modulating the amount of sulfur template used, it is possible to precisely control the three-dimensional graphene carbon cage structure, and to achieve a "fit" coating of non-carbon active particles, thereby effectively buffering the large volume expansion of non-carbon active particles in lithium, as lithium The ion battery anode exhibits excellent volume properties.
Accurate design of graphene carbon cage structure by graph sulfur template method
The sulfur template method is proposed in the three-dimensional graphene dense network, using the characteristics of fluidity, amorphous, and easy removal of sulfur like "Transformers", and realizing non-carbon active particles inside the carbon cage structure. Tight coating of tin oxide nanoparticles. 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 a sturdy and precisely controlled space. The "tailoring" of active tin dioxide. The carbon-non-carbon composite electrode material having a suitable reserved space and maintaining a high density can contribute extremely high volumetric capacity, thereby greatly increasing the volumetric energy density of the lithium ion battery and making the lithium ion battery smaller. This "tailor-made" design idea can be extended to the construction strategy of the next-generation high-energy lithium-ion battery, lithium-sulfur battery, lithium-air battery and other electrode materials.
Professor Yang Quanhong's research team has made a series of important advances in the field of dense energy storage, which emphasizes the volumetric performance of devices. Invented the capillary evaporation densification strategy of graphene gel, which solved the high density and porosity of carbon materials. The bottleneck problem can not be achieved, the high-density porous carbon material is obtained; the small volume and high capacity of the energy storage device are pursued, and the high-volume energy density energy storage device is proposed from five aspects: strategy, method, material, electrode and device. The design principle finally realizes the construction of high-volume energy storage materials, electrodes and devices from supercapacitors, sodium ion capacitors, lithium-sulfur batteries, lithium-air batteries to lithium-ion batteries, laying a foundation for the practical application of carbon nanomaterials. The practical process of new electrochemical energy storage devices based on carbon nanomaterials has been vigorously promoted.
(The original title is "Tianjin University Yang Quanhong team made breakthroughs in the design of electrode materials for high-volume energy density lithium-ion batteries")
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