Imidazolium-based ionic liquid mixtures with [NO3]− and [AlCl4]− anions were used as oxidizing agents for the dissolution of Au, Pd, and Pt metals under mild conditions. The thermodynamic reduction of [NO3]− to [NO] is catalyzed by [AlCl4]− anions and coupled with the oxidation process of noble metals. The developed ionic liquid system for dissolving Au can reactivate the Au0 formed in the deactivation process of the catalyst in vinyl chloride production. This demonstrates the relevance of the here-presented work for technical noble metal recycling.
Wang Jun-xiang,Tu Ji-guo,Jiao Han-dong,Zhu Hong-min
Aluminum storage systems with graphite cathode have been greatly promoting the development of state-of-the-art rechargeable aluminum batteries over the last five years; this is due to the ultra-stable cycling, high capacity, and good safety of the systems. This study discussed the change of electrochemical behaviors caused by the structural difference between flake graphite and expandable graphite, the effects of temperature on the electrochemical performance of graphite in low-cost AlCl 3 –NaCl inorganic molten salt, and the reaction mechanisms of aluminum complex ions in both graphite materials by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, cyclic voltammetry, and galvanostatic charge–discharge measurements. It was found that flake graphite stacked with noticeably small and thin graphene nanosheets exhibited high capacity and fairly good rate capability. The battery could achieve a high capacity of ∼219 mA hg −1 over 1200 cycles at a high current density of 5 Ag −1 , with Coulombic efficiency of 94.1%. Moreover, the reaction mechanisms are clarified: For the flake graphite with small and thin graphene nanosheets and high mesopore structures, the reaction mechanism consisted of not only the intercalation of \({\rm{AlCl}}_4^ - \) anions between graphene layers but also the adsorption of \({\rm{AlCl}}_4^ - \) anions within mesopores; however, for the well-stacked and highly parallel layered large-size expandable graphite, the reaction mechanism mainly involved the intercalation of \({\rm{AlCl}}_4^ - \) anions.
Wending Pan,Yan Zhao,Jianjun Mao,Yifei Wang,Xiaolong Zhao,Kee Wah Leong,Shijing Luo,Xinhua Liu,Huizhi Wang,Jin Xuan,Shichun Yang,Yue Chen,Dennis Y. C. Leung
The aqueous Al-ion battery has achieved great progress in recent years. It now shows comparable performance to that of even non-aqueous Al-ion batteries. However, it also shows relatively low energy output and there is limited general understanding of the mechanism behind this restriction to its practical application. Thus, the development of a high-performance cathode material is in great demand. Herein, a high-capacity single-walled carbon nanotube (SWCNT) is developed as a cathode for the water-in-salt electrolyte-based aqueous Al-ion battery, which provides an ultra-high specific capacity of 790 mAh g –1 ( based on the mass of SWCNT ) at a high current density of 5 A g –1 even after 1000 cycles. Moreover, the SWCNT/Al battery shows a complicated multi-ion intercalation mechanism, where AlCl 4 – , Cl – , Al 3+ , and H + can function at the same time, improving the battery output. Beyond recently revealed H + and metal ion co-intercalation, the Cl-assisted intercalation of Al 3+ ions mechanism is also studied by experimental characterization and modeling for the first time, which significantly boosts the Al 3+ storage capacity. This multi-ion intercalation mechanism combines the high-voltage anion deintercalation and the high-capacity cation intercalation, and thus, benefits the development and application of high-energy Al-ion batteries in the future.
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