Nankai University has made significant progress in flexible lithium-sulfur battery electrode materials

by:CTECHi     2021-08-13

With the rapid development of portable electronic equipment, electric vehicles and space technology, they have put forward higher and higher requirements on the energy density, power density and flexibility of batteries. Among various energy storage devices, lithium Sulfur batteries have an energy density (2567Whkg-1) that is one order of magnitude higher than that of traditional lithium-ion batteries. Moreover, sulfur has a wide range of sources, low prices, and good environmental compatibility, which has attracted widespread attention.

Although people have made great progress in the field of lithium-sulfur batteries in recent years, lithium-sulfur batteries are still facing a series of problems, including: the use of active material sulfur Low rate, poor cycle stability and low coulombic efficiency. In order to solve these problems, the traditional method usually composites sulfur and carbon materials, and then mixes the composite material of sulfur and carbon with a conductive agent to coat the current collector as the electrode material of the lithium-sulfur battery.

However, the addition of current collectors and binders will increase the weight of the electrode and affect the electrochemical performance of lithium-sulfur batteries. In addition, the mechanical properties of traditional lithium-sulfur battery electrodes are relatively It is poor and cannot be used as an electrode material for flexible lithium-sulfur batteries. Recently, the Niu Zhiqiang research team of Nankai University combined in-situ composite and metal reduction self-assembly methods to prepare a self-supporting flexible graphene/sulfur nanocomposite film. The graphene in the composite film has a continuous network structure, and the sulfur is uniformly dispersed in the graphene. On the surface, the continuous network structure of graphene not only provides an effective way for ion and electron transport, but also effectively adsorbs polysulfides and inhibits their dissolution.

Because the composite film has high conductivity, it does not require a current collector and can be directly used as an electrode material for lithium-sulfur batteries, and the composite film exhibits excellent Charge and discharge capacity (first lap discharge capacity: 1302mAhg-1), cycle stability and rate performance. In addition, the unique structure of the graphene/sulfur nanocomposite film makes it have excellent mechanical properties and can maintain the electrical properties under different bending conditions. Therefore, the composite film can be used as an electrode material for a flexible lithium-sulfur battery. In this work, two flexible lithium-sulfur batteries with soft pack and linear structures are designed in this work. Both flexible lithium-sulfur battery devices exhibit stable electrochemical performance under bending conditions.

This research has played an active role in promoting the application of lithium-sulfur batteries in related fields such as flexible and wearable electronic devices.

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