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In-situ method to construct interlayer in NiO@NiO/NF self-supporting material for high area specific capacity lithium ion battery

2019-05-31 来源:亚科官网
 
In practical applications in various electronic devices, electric vehicles, aerospace and other fields, the area specific capacity of lithium-ion batteries is a crucial parameter. Therefore, it is important to construct a stable electrode with high active material loading and high area specific capacity. Recently, Professor Sun Haizhu of Northeast Normal University successfully synthesized NiO@NiO/NF multilayer material by one-step solvothermal and annealing method. As a lithium ion battery electrode material, it exhibits excellent electrochemical performance and good stability.
Most of the current reports focus on the mass-to-capacity of active materials in the electrodes. Usually, the active material is uniformly mixed with the conductive agent and the binder, and then thinly coated on the conductive current collector, which results in a lower proportion of the active material and its content in the electrode, thereby affecting the entire electrode. Mass specific capacity and area specific capacity. The self-supporting material can avoid the use of the conductive agent and the binder, but the conventional method of directly growing the active material on the current collector does not ensure that the active material remains attached to the current collector after multiple charge and discharge cycles, and the quality is introduced. A current collector that is too heavy to contribute to capacity results in a decrease in the overall mass-to-capacity of the electrode.
The multi-layer NiO@NiO/NF self-supporting material composed by Professor Sun Haizhu of Northeast Normal University effectively solved the above problems. In the NiO@NiO/NF multilayer material, Ni(OH)2 nanoflowers are uniformly grown on the surface of the foamed nickel by one-step solvothermal reaction, and then the nickel oxide is partially oxidized by accurately controlling the annealing conditions to form the surface layer NiO. A multi-layered structure in which nanoflowers, interlayer NiO, and foamed nickel (NF) skeletons alternate. Among them, the interlayer derived from the oxidation of the foamed nickel skeleton effectively enhances the adhesion between the layers. After 1000 cycles of charge and discharge, the surface nanoflowers are still tightly attached to the skeleton, and the material as a whole still maintains good integrity and flexibility. Since the foamed nickel skeleton forms an interlayer in situ, the portion of the skeleton which is originally heavy and does not contribute to the capacity becomes an active material, contributes capacity to the entire material, and increases the amount of active material to obtain an electrode having a high specific area capacity.
The material achieves a capacity of 1.98 mAh cm-2 at a current density of 1.20 mA cm-2 and remains at 1.45 mAh cm-2 after 100 cycles. SEM and CV tests further demonstrate the important role of the interlayer and the mechanism of gradual lithium storage. By comparison with NiO@NiO/NF-500, it was proved that the material containing the interlayer had stronger interlayer adhesion, and the active material did not fall off after 1000 cycles.
This achievement was recently published in Advanced Energy Materials. The first author of the article was Li Yanfei, a Ph.D. student at Northeast Normal University, and Dr. Fan Chaoying, co-author.
Edited by Suzhou Yacoo Science Co., Ltd.