Recently, Tang Yongbing, a researcher of the Functional Thin Film Materials Research Center of the Institute of Advanced Technology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences and his research team have successfully developed a new type of high-efficiency calcium ion hybrid energy storage device that can work at room temperature. The best performance of the system. Related research results "A Calcium-Ion Hybrid Energy Storage Device with High Capacity and Long Cycling Life under Room Temperature" have been published online in the international journal Advanced Energy Materials ("Advanced Energy Materials", Adv. Energy Mater. 2019, 1803865).
The calcium storage is rich, which is 2500 times that of lithium. It can provide a two-electron reaction and has excellent kinetic properties. Therefore, calcium ion energy storage devices are expected to become a new generation of efficient and low-cost energy storage technology. However, in the past two decades, the positive and negative electrode materials required for calcium ion energy storage technology have developed slowly. The lack of a suitable combination of electrode material and electrolyte makes it difficult to build a complete energy storage device based on a rocking chair working mechanism, thereby seriously hindering the development of calcium ion energy storage technology. Research in this field has found that the use of a multi-ion working mechanism in which anions react with positive electrodes and cations react with negative electrodes is expected to solve the above problems. In multi-ion working devices, super capacitors based on non-Faraday reaction have advantages such as long life and high rate, but their operating voltage and capacity are low; while the dual ion battery based on Faraday reaction has high voltage and high capacity, but due to The destruction of the positive electrode structure by anions makes the cycle performance and rate performance poor.
In order to solve the above problems, Tang Yongbing and his team members Wu Nanzhong, Yao Wenjiao and others have developed a new type of calcium ion hybrid energy storage device. The device uses capacitor-type material activated carbon as the positive electrode, battery-type material tin foil as the negative electrode, and Ca (PF6) 2 as the working electrolyte. When the battery is charged, PF6- reacts with activated carbon, Ca2 + alloys with tin foil, and the discharge process is reversed. The calcium ion energy storage device effectively utilizes the respective characteristics of supercapacitors and dual ion batteries, thereby obtaining high voltage, large capacity and high rate performance, and exhibits excellent cycle stability at room temperature, at 0.2 A / g At current density, after 1000 cycles, the capacity retention rate is as high as 84%.
The research was supported by the National Natural Science Foundation of China, the Chinese Academy of Sciences, Guangdong Science and Technology Plan Project, Shenzhen Peacock Plan, Shenzhen Science and Technology Plan Project, etc.
Figure: (a) Supercapacitor, (b) dual ion battery and (c) hybrid energy storage device during the charging process (positive (red line), negative (blue line) polar potential changes; (d) calcium ion hybrid energy storage device Cycling stability, after 1000 cycles, the capacity retention rate is 84%; (e) The charge-discharge curve of the calcium ion hybrid energy storage device under different cycle times.
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