Scientists say batteries may become smaller

Date:Apr 27, 2020

How can electronic consumer products such as mobile phones and laptops be lighter and thinner, and how can electric vehicles have a longer range of power in a limited body space ... With the growing demand for energy storage, the performance of secondary batteries is also Raised higher and higher requirements. Nanotechnology can make batteries "lighter" and "faster", but due to the lower density of nanomaterials, "smaller" has become a difficult problem for researchers in the field of energy storage.

The research team of Professor Yang Quanhong, a recipient of the National Outstanding Young Science Foundation and the School of Chemical Engineering of Tianjin University, proposed the “sulfur template method”. Through the design of the anode material for high-volume energy density lithium ion batteries, the “tailor-made” of graphene wrapped with active particles was finally completed It is possible to make lithium-ion batteries "smaller". The result was published online in "NatureCommunicaTIons" on January 26.

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 the current commercial graphite as a new-generation anode material, greatly improving the mass energy density (Whkg-1) of lithium-ion batteries, but their huge volume expansion severely limits their advantages in volume performance. The carbon cage structure constructed by carbon nanomaterials is considered to be an important means to solve the huge volume expansion problem of non-carbon anode materials when lithium is intercalated; however, during the construction of the carbon buffer network, too much reserved space is often introduced, resulting in electrode material The density is greatly reduced, which limits the performance of the volume 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's research team and Tsinghua University, the National Nano Center, and the National Institute of Materials Research in Japan have made breakthroughs in the design of anode materials for high-volume energy density lithium-ion batteries. Based on the graphene interface assembly, they have invented the precise customization of dense porous carbon cage Sulfur template technology. In the process of using capillary evaporation technology to build a dense graphene network, they introduced sulfur as a flowable volume template to complete the customization of the graphene carbon coat for non-carbon active particles. By adjusting the amount of sulfur template used, the three-dimensional graphene carbon cage structure can be precisely adjusted to achieve a "fit" coating of the size of the non-carbon active particles, so as to effectively buffer the huge volume expansion of the non-carbon active particles embedded lithium, as a lithium The negative electrode of the ion battery shows excellent volume performance.

The sulfur template method is proposed to use the characteristics of sulfur, such as "transformers", fluidity, amorphousness, and easy removal in a dense network of three-dimensional graphene, to achieve non-carbon active particles like two in the carbon cage structure. The 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 suitable shape and accurate and controllable reserved space. Tailor-made tailoring of active tin dioxide. This kind of carbon-non-carbon composite electrode material with suitable reserved space and high density can contribute extremely high volume specific capacity, thereby greatly increasing the volume energy density of lithium ion batteries and making lithium ion batteries smaller. This "tailor-made" design idea can be extended to the construction of universal next-generation high-energy lithium-ion batteries and lithium-sulfur batteries, lithium-air batteries and other electrode materials.

Professor Yang Quanhong ’s research team has made a series of important advances in the field of dense energy storage that emphasizes the volumetric performance of devices in recent years, inventing the capillary evaporation densification strategy of graphene gel, which solves the high density and porosity of carbon materials. The bottleneck problem of "unavailable" is to obtain high-density porous carbon materials; to pursue the small volume and high capacity of energy storage devices, high volume energy density energy storage devices are proposed from five aspects: strategies, methods, materials, electrodes, and devices The design principles of the design have finally realized the construction of high-volume capacity 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. It has effectively promoted the practical process of new electrochemical energy storage devices based on carbon nanomaterials.

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