Under the support of the National Natural Science Foundation of China, the China Youth Science Citation Academy Young Talent Lift Project and Beijing Institute of Technology's Science and Technology Innovation Program, the research group of Huang Jiaqi, a leading researcher at the Frontier Crossing Research Institute of Beijing Institute of Technology, is working on the next generation of high energy density lithium metal batteries Recently, the related research results are published in "Advanced Functional Materials" on January 8, 2018 entitled "Artificial soft-rigid protective layer for dendrite-free lithium metal anode" (Advanced Functional Materials, Impact Factor 12.124).
'Rigid and Gentle' composite membrane modified interface can be effectively attached to the surface of lithium metal, and inhibit the dendritic growth diagram
Lithium metal is considered as one of the most promising high specific energy anode materials due to its extremely high theoretical specific capacity (3860 mA hg-1) and the most negative electrode potential (-3.045 V vs. standard hydrogen electrode). However, the practical application of lithium metal electrodes is limited by the growth of lithium dendrites and low cycle efficiency.Lithium metal is a highly active metal, which forms a solid electrolyte interface with complex structure and composition when in contact with the electrolyte. In the electrochemical reaction It is difficult to maintain the stability of the interface during the process so that inhomogeneous deposition of lithium ions at the interface easily causes acicular, dendritic, and mossy lithium deposition.The growth of lithium dendrites punctures the separator on the one hand and shorts , Resulting in security risks; on the other hand also increased the contact area of lithium metal and electrolyte, making side reactions increased, the battery cycle efficiency further decline.
In order to establish a stable lithium / electrolyte interface and control the uniform deposition of lithium, the research group proposed to use inorganic LiF as a rigid component and PVDF-HFP as a flexible component to construct a rigid- Electrochemical cycling stabilizes the interface between lithium metal and the electrolyte, where the flexibility and scalability provided by the flexible polymer can withstand the interface fluctuations during the deposition / dissolution of the lithium metal electrode, and the introduction of the rigid component can further enhance the modification Layer, thereby inhibiting the growth of lithium dendrites and realizing the uniform deposition of lithium.When this interfacial layer with good deformability, high mechanical modulus and ionic conductivity is introduced into the coin cell, Li -Cu half-cell, Li-Li symmetric battery cycle life and cycle stability are significantly improved; and lithium iron phosphate positive all-battery test, the composite layer modified battery cycle life increased by 2.5 times.