Dalian Chemical revealed the efficient ion transport mechanism of high-dielectric composite solid electrolyte

The cover image was produced by the Science Visualization Center of China Science Daily

Recently, Zhong Guiming, associate researcher of the Genealogical Electrochemistry and Lithium-ion Battery Research Group of the Fuel Cell Research Department of the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and the team of Professor Kang Feiyu and Professor He Yanbing of the Shenzhen Research Institute of Tsinghua University have made new progress in the research of polymer-inorganic composite solid electrolytes, and developed PVDF, LiTFSI and BaTiO3– A high-dielectric composite solid electrolyte (PVBL) constructed with Li0.33La0.56TiO3-x side-by-side heterostructure proposed and verified the multi-channel collaborative ion transport mechanism centered on the two-phase interface under the action of interfacial electric field.

On March 9, 2023, the relevant results were recently published in the journal Nature Nanotechnology with the title “A dielectric electrolyte composite with high lithium-ion conductivity for high-voltage solid-state lithium metal batteries”.

Polymer-inorganic composite electrolytes have the advantages of flexibility, easy preparation, and high compatibility with commercial lithium-ion battery preparation processes, which has become an important way to realize solid-state batteries. However, these electrolytes are subject to low ionic conductivity properties. How to break through the limitation of polymer ion transport principle has become a key problem in the research of polymer solid electrolytes. In his previous work, Zhong Guiming used isotope tracing NMR spectroscopy to reveal the interfacial ion transport path of composite solid electrolyte and the constraints of two-phase interfacial transport barrier on efficient ion transport (Angew. Chem.,2021;J. Phys. Chem. Lett.,2022)。

In this work, the collaborative team found that the local electric field generated by high-dielectric ceramics in the side-by-side structure BaTiO3–Li0.33La0.56TiO3–x can promote the dissociation of LiTFSI in PVDF phase and weaken the ion transport barrier between PVDF and LLTO. At the same time, LiTFSI and residual solvent are more likely to accumulate on the surface of inorganic electrolyte due to the strong complexation between inorganic electrolyte and solvent. Based on this, the cooperative team proves that the constructed multi-channel collaborative and efficient transmission paths such as PVDF phase, LLTO phase and interface are the key to achieving high room temperature ion conductivity (8.2×10-4 S cm-1). The bound residual solvent molecules also provide the feasibility for stabilizing the metal anode interface. The efficient ion transport mechanism and construction strategy proposed in this study provide new ideas and methods for the development of polymer electrolytes.

This work has been supported by the National Key Research and Development Program of China, the National Natural Science Foundation of China and other projects. (Source: Science Network)

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