China University of Science and Technology diatomite multi-level structure to develop high-performance solid-state lithium battery composite negative
Lithium metal is an ideal anode material for new high-specific energy batteries due to its high specific capacity and low redox potential. However, the commercialization of lithium metal batteries has been limited by safety issues and limited cycle life. Replacing traditional flammable organic electrolytes with new non-flammable solid electrolytes can significantly reduce the risk of fire and explosion of lithium metal batteries. However, due to the limited solid-solid interface contact between the solid electrolyte and the electrode material, the electrochemical performance of the solid-state lithium metal battery is limited and cannot meet the needs of practical applications. From the perspective of the negative electrode of a solid-state lithium metal battery, the construction of a solid multi-level lithium metal composite negative electrode requires an ideal frame material. The frame material should have the following characteristics: 1) Rich sources and low cost; 2) Strong affinity for lithium metal; 3) Rich pore structure to accommodate lithium metal. Therefore, it is an effective way to improve the performance of solid-state lithium metal battery by using multi-level structure design to enhance interface contact inside the electrode.
Recently, the team of Yao Hongbin and the team of Yu Shuhong of the University of Science and Technology of China were inspired by the multi-level structural characteristics of diatomaceous earth, using natural diatomaceous earth as a template to successfully prepare a solid multi-level structure lithium metal solid composite with no dendrite growth As a negative electrode, a solid lithium metal battery constructed based on the lithium metal composite negative electrode exhibits excellent electrochemical performance. The work was published in "Nature-Communications" (Nature Communations 2019, 10, 2482) under the title of "Diatomaceous earth-derived multi-stage composite anodes for high-performance all-solid lithium metal batteries" on June 6. The first author of the paper is post-doctor Zhou Fei.
The researchers first converted the natural diatomaceous earth into a silicon framework with a multi-level pore structure by magnesia reduction. Subsequently, the multi-level structure silicon frame is mixed with molten lithium metal and fully stirred and reacted to produce a lithium-silicon composite powder. Then, polyethylene oxide polymer solid electrolyte (PEO-SPE) was used to modify the surface of the lithium-silicon powder. Finally, the above-mentioned powder was pressed into a composite lithium metal negative electrode (PEO-DLSL) with a multi-stage structure through a cold pressing process (Figure 1a). In PEO-DLSL, lithium metal is embedded in the pore structure of the Li4.4Si frame modified by PEO-SPE, thereby increasing its contact area with the electrolyte, which is conducive to more uniform lithium ion flow and maintains the electrode structure Integrity. Therefore, at higher current density (> 0.5 mA cm-2), the multi-level structure lithium metal composite anode can achieve uniform deposition and extraction of lithium metal, effectively inhibiting the growth of lithium dendrites (Figure 1b). For the traditional flat lithium foil, under the same conditions, lithium dendrites are easy to grow and cause battery short circuit (Figure 1c).
Using PEO-SPE as a solid electrolyte, the PEO-DLSL symmetrical battery can be cycled for more than 1000 hours without short-circuit in the lithium extraction / deposition test, while the polarization voltage can be kept below 100 mV. The conventional lithium foil negative electrode shows a very high polarization voltage (more than 200 mV) and a short circuit occurs after 50 cycles (Figure 2a). The researchers further investigated the performance of PEO-DLSL in all-solid-state lithium metal batteries (PEO-SPE is a solid electrolyte and lithium iron phosphate is a positive electrode). As shown in Figure 2b, PEO-DLSL-based solid-state lithium metal batteries show very Good cycle stability (500 cycles at 0.5C rate, capacity decay rate of 0.04% / per cycle), and solid-state lithium metal batteries using flat lithium foils short-circuited after 75 cycles (Figure 2a).
In summary, based on the diatomite multi-level channel structure template, the researchers successfully constructed a multi-level structure lithium metal composite negative electrode, which showed outstanding electrochemical performance in the application of all-solid lithium metal battery. This research is a new attempt of the natural multi-level structure template in the preparation of high-performance solid-state lithium metal composite anodes, and will provide new structural design ideas for the development of high specific energy / high safety energy storage devices.
The research was supported by the National Natural Science Foundation of China Innovation Research Group, the National Natural Science Foundation of China Key Projects, the Chinese Academy of Sciences Frontier Science Key Research Projects, the Chinese Academy of Sciences Nanoscience Excellence Innovation Center, the Suzhou Nanotechnology Collaborative Innovation Center, etc.
Figure 1: (a) Schematic diagram of the preparation process of multi-layer structure solid lithium metal composite negative electrode derived from diatomite template. (B) Schematic diagram of lithium deposition / extraction of a multi-level solid lithium metal composite anode. (C) Schematic diagram of lithium deposition / extraction of a flat lithium foil anode.
Figure 2: (a) Comparison of symmetric battery cycle performance between a multi-stage lithium metal composite anode and a flat lithium foil. (B) Comparison of the cycling performance of all-solid-state lithium metal batteries with multi-level lithium metal composite anodes and flat lithium foils.
Knitting Machine Sensor,Textile Sensors,Fabric Stretch Sensor,Sensors Location On The Knitting Machine
Changzhou Longfu Knitting Co., Ltd. , https://www.circularmachine.com