On August 21st, the top academic journal "Matter" published the latest achievements of Professor Ma Cheng and his collaborators from the University of Science and Technology of China. This achievement proposes a new strategy that can effectively solve the critical problem of poor contact between the electrode material and the solid electrolyte in the next-generation solid-state lithium battery. The synthesized solid composite electrode exhibits excellent capacity and rate performance.
The current mainstream lithium batteries use liquid electrolytes, there are potential safety hazards such as fire, and the energy that can be stored in a specific volume is limited, but the next-generation solid-state lithium batteries that can solve these problems still have many unsolved problems. Replacing the organic liquid electrolyte in traditional lithium-ion batteries with solid electrolytes can greatly alleviate safety issues and is expected to break through the "glass ceiling" of energy density. However, the mainstream electrode material is also a solid substance. Since the contact between the two solid substances is almost impossible as full as the solid-liquid contact, it is difficult to achieve good electrode-electrolyte contact in batteries using solid electrolytes at present, and the overall performance of the battery is not Satisfactory.
Ma Cheng's team and collaborators conducted atomic-level observations on the impurity phase in a classic perovskite structured solid electrolyte. Although the structure of the impurities and the solid electrolyte are very different, the researchers observed that their atoms can interact with each other at the interface. Arranged in the form of extension. After a series of detailed structural and chemical analysis, the researchers found that this impurity phase has the same structure as the high-capacity lithium-rich layered electrode.
Using the observations, the researchers crystallized the amorphous powder with the same composition as the perovskite solid electrolyte on the surface of the lithium-rich layered particles, and successfully achieved a sufficient and close relationship between the two solid materials in the new composite electrode. contact. Solving the electrode-electrolyte contact problem, the rate performance of this solid-solid composite electrode is comparable to that of a solid-liquid composite electrode. More importantly, the researchers also found that this epitaxial solid-solid contact can tolerate a large lattice mismatch, so the strategy they proposed can be applied to a variety of perovskite solid electrolytes and layered electrodes. (Reporter Chen Hua)
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