Tang Yongbing said that this new structure effectively solves the problem of volume expansion and poor cycle performance of inexpensive metal anode materials during charge and discharge. Related research results The ultra-stable solid electrolyte layer formed by the foam paper interface and its application in high-efficiency dual-ion batteries have been published online in AdvancedMaterials, the top journal of materials science.
With the rapid development of the market for portable electronic devices and electric vehicles, there is an increasing demand for high energy density, low cost secondary batteries. At present, commercial lithium-ion batteries mostly use graphite-based anode materials, and their theoretical specific capacity is only 372 mAhg-1, and the compaction density is low, which limits the further improvement of the energy density of lithium-ion batteries.
It is reported that an inexpensive metal negative electrode usually has a larger specific capacity by alloying/de-alloying reaction with lithium ions, and it is expected to obtain a higher energy density. “The theoretical specific capacity of aluminum is as high as 2234 mAhg-1 (Li9Al4), and the reserves are abundant and the price is low.” Tang Yongbing said, “However, the aluminum negative electrode will have a certain volume expansion during the battery reaction process, thus affecting the cycle stability of the battery. ."
Based on the above considerations, Tang Yongbing and his team members Qin Panpan, Wang Meng, Li Na and others successfully developed a metal aluminum foil material with a hollow interface microstructure, and simultaneously integrated the active material and current collector, and Successfully applied to new high efficiency, low cost dual ion secondary batteries.
Tang Yongbing said: "We use structural design, modified aluminum foil as both negative active material and current collector, expanded graphite as positive electrode, and use conventional electrolyte. Compared with traditional lithium ion batteries, the new secondary energy storage battery has higher The operating voltage (average discharge voltage is ~4.2V), while significantly increasing the proportion of active materials and energy density, and significantly reducing manufacturing costs, and environmentally friendly."
In addition, the interface design of the hollow microstructure enables the lithium-aluminum alloy to be successfully confined in the hollow interface, thereby effectively alleviating the volume expansion of the aluminum anode during the alloying process, and obtaining a highly stable SEI film.
The results show that the new battery is 1500 cycles at a half-hour charge and discharge rate (2C), and the capacity retention rate is as high as 99%. In addition, even when the power density is as high as 2113Wkg-1, the energy density of the battery is still 169Whkg-1. (10C, charge and discharge time is 6 minutes), much higher than most commercial lithium-ion batteries.
Tang Yongbing pointed out: "Our research results have guiding significance for the development of low-cost metal anode materials, and it is expected to promote the development of high-energy, low-cost secondary batteries based on inexpensive metal anodes."