Recently, the research group of Qianfeng Fang, a researcher at the Institute of Internal Friction and Solid Defects, Institute of Solid State Physics, Hefei Institute of Materials Science, Chinese Academy of Sciences, has designed an asymmetric structure for studying the deposition and transport patterns of lithium ions in solid state batteries. The growth and suppression mechanism of lithium dendritic crystals in lithium batteries provides an important reference. The related research results were published in the journal Power Sources under the title Intracrystalline growth of lithium metal in Li7La3Zr2O12 electrolyte and the mechanism of uniform distribution of lithium metal.
With high energy density, strong stability and long cycle life, lithium-ion batteries have been widely used as commercial and efficient energy storage devices. However, due to the use of flammable organic electrolytes in commercial lithium-ion batteries, fires and even explosions can easily occur when the batteries are subjected to high temperatures, short circuits, overcharging or physical damage. Therefore, using a non-flammable inorganic solid electrolyte instead of a liquid electrolyte is one of the most effective ways to solve the safety problem of lithium batteries. However, since lithium ions spontaneously form dendritic lithium dendritic crystals during the deposition process at the negative electrode, their sharp structures easily pierce the diaphragm, leading to battery short circuit and potential safety hazards. Therefore, the use of inorganic solid electrolytes instead of liquid organic electrolytes to effectively inhibit the growth of lithium dendritic lithium during charging and discharging can better address the safety issues of lithium-ion batteries and properly understand the deposition and transport of lithium ions in solids. This process in solid-state batteries is critical to inhibit the growth of lithium dendritic crystals and prevent short-circuiting of the battery.
Therefore, researchers designed solid-state batteries with an asymmetric structure by designing the lithium metal electrodes on both sides of the electrolyte to be perpendicular to each other (Figure 1a), and inferred that lithium is deposited on the electrolyte surface by observing the state of lithium. The transport process of ions inside the electrolyte. Meanwhile, the Au atomic layer was sputtered on the central region of the electrolyte surface layer and the effect law of Au atomic layer on lithium deposition compared to the area of the unsputtered Au atomic layer obtained ions. The results show that the electron distribution on the electrolyte surface directly affects the transport path of lithium ions in the electrolyte (Figure 1b), so that the lithium ions from the upper surface of the electrolyte are dispersed in the electrolyte. Further analysis revealed that in the unsputtered Au sputtering region, the lithium ions deposited in the irregular region (the left area of the blue box in Fig. 1a) show an enriched distribution state, which induces the growth of lithium dendritic crystals and causes short circuits. . In the region sputtered with Au atomic layer, the lithium ions are deposited in a uniform spherical particle distribution (red boxed region in Fig. 1a and the right region in the blue box), which effectively suppresses the lithium ions induced by the growth of Al. potential safety hazards of lithium dendrite cells. The development of this work provides the theoretical and experimental basis for optimizing the interface performance and safety performance of all solid-state batteries.
This research work was supported by the National Natural Science Foundation of China and the Anhui Natural Science Foundation.
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