How mobile phones, laptops and other electronic consumer goods are lighter and thinner, how electric vehicles have a longer range of electricity in a limited body space ... With the growing demand for energy storage, the performance of secondary batteries is also Proposed higher and higher requirements. Nanotechnology can make batteries 'lighter', 'faster', but due to the lower density of nanomaterials, 'smaller' becomes a problem facing scientific researchers in the field of energy storage. .
The winner of the National Outstanding Young Scientists Fund, Professor Yang Quanhong of the Tianjin University’s School of Chemical Engineering proposed the 'sulfur template method'. By designing the anode material for high-volume energy density lithium-ion batteries, the graphene-coated active particles were finally completed. It became possible to make lithium-ion batteries 'smaller'. This result was published online on January 26th in Nature Communications (2018, 9, 402).
As the most widely used secondary battery at present, lithium ion batteries have a very high energy density. Non-carbon materials such as tin and silicon are expected to replace the current commercial graphite as a new generation of negative electrode material, which significantly increases the mass energy density of lithium ion batteries (Wh kg -1), but its large volume expansion has severely limited the performance of its volumetric performance. The carbon cage structure constructed of carbon nanomaterials is considered to be the main means to solve the problem of huge volume expansion when lithium is inserted in non-carbon negative materials; but in carbon In the process of constructing a buffer network, too many reserved spaces are often introduced, resulting in a drastic decrease in the density of electrode materials, which limits the negative volume performance of lithium-ion batteries. Therefore, the accurate customization of carbon cage structures is not only an important academic problem. , It is also the only way for the industrialization of new high-performance anode materials.
Prof. Yang Quanhong’s research team collaborated with Tsinghua University, the National Nano Center, and the Japanese National Materials Research Institute's collaborators to achieve breakthroughs in the design of anode materials for high volume energy density lithium-ion batteries. Based on the graphene interface assembly, invented the precise customization of dense porous carbon cages. The sulfur template technique. In the process of constructing a dense graphene network by capillary evaporation technique, they introduced sulfur as a flowable volume template and completed the customization of the graphene carbon sheath for non-carbon reactive particles. The amount can accurately control the three-dimensional graphene carbon cage structure and achieve the 'fit' coating of the non-carbon active particles, thereby demonstrating as a negative electrode of the lithium ion battery based on the effective buffering of the large volume expansion of the non-carbon active particle intercalation lithium. Excellent volume performance.
The sulphur template method is proposed in the three-dimensional graphene dense network. It uses the same characteristics of sulfur as the 'Transformers', such as fluidity, amorphousness, and easy removal, to realize non-carbon reactive particles in a carbon cage structure. Compact encapsulation of tin oxide nanoparticles. Compared to conventional 'shape' templates, the biggest advantage of the sulfur template is that it can act as a plastic volumetric template, allowing the compact graphene cage structure to provide conformal and precise dimensions. The reserved space for control will eventually complete the tailor-made activity for active tin dioxide. This kind of carbon-non-carbon composite electrode material with suitable reserved space and high density can contribute a very high volumetric capacity, and thus significantly Improve the volumetric energy density of lithium-ion batteries to make them even smaller. This 'tailored' design concept can be expanded to the next generation of high-energy lithium-ion batteries and lithium-sulfur batteries, lithium-air batteries and other electrode materials. The construction strategy.
Prof. Yang Quanhong’s research team has made a series of important progresses in recent years in the area of compact energy storage that emphasizes the volumetric performance of the device. He invented a capillary evaporation densification strategy for graphene gels, which solved the high density and porosity of carbon materials. Can not have both the 'bottleneck problem, get a high density of porous carbon materials; the pursuit of energy storage device's small size, high capacity, from the five aspects of strategy, methods, materials, electrodes, devices and other high-energy energy density energy storage devices Based on the design principles, supercapacitors, sodium-ion capacitors, lithium-sulfur batteries, lithium-air batteries, and lithium-ion batteries have finally led to the construction of high-capacity energy storage materials, electrodes, and devices, laying the foundation for the practical application of carbon nanomaterials. The process of practical application of a new electrochemical energy storage device based on carbon nanomaterials was strongly promoted.
