Below the 12-vertex: 10-vertex carborane anions as non-corrosive, halide free, electrolytes for rechargeable Mg batteries

The development of practical Mg based batteries is limited by the lack of a library of suitable electrolytes. Recently a 12-vertex closo-carborane anion based electrolyte has been shown to be the first electrolyte for Mg based batteries, which is both non-corrosive and has high electrochemical stability (+3.5 V vs. Mg0/2+). Herein we show that smaller 10-vertex closo-carborane anions also enable electrolytes for Mg batteries. Reduction of the trimethylammonium cation of [HNMe31+][HCB9H91-] with elemental Mg yields the novel magnesium electrolyte [Mg2+][HCB9H91-]2. The electrolyte displays excellent electrochemical stability, is non-nucleophilic, reversibly deposits and strips Mg, and is halide free. This discovery paves the way for the development of libraries of Mg electrolytes based on more cost effective 10-vertex closo-carborane anions

Reversible Electrochemical Intercalation of Aluminum in Transition Metal Sulfides

Rechargeable battery technology has been one of the most exciting advancements in science and technology in the last several decades. Even though lithium ion battery technology has achieved great success in many fields, its wide deployment for large-scale energy storage is very questionable because of the limited resources of lithium. Therefore, alternative rechargeable battery technologies based on abundant elements need to be developed for sustainable electrochemical energy storage. Among all the potential candidates, battery systems based on aluminum as anode is particularly promising. In this thesis, we are dedicated to develop novel rechargeable Al-ion battery prototypes mainly focusing on cathode materials. Our achievement of discovering transition metal sulfides as promising cathode materials for rechargeable Al-ion batteries is pioneering. We first proposed Chevrel Phase Mo6S8 as intercalation-type cathode material for rechargeable Al-ion battery using ionic liquid electrolyte. We investigated the electrochemical properties as well as compositional properties of Chevrel Phase Mo6S8 as a cathode material. We believe it is the first reported intercalation-type rechargeable Al-ion battery prototype. We went further to probe the detailed intercalation process of Al3+ in Chevrel phase Mo6S8. High quality powder XRD data along with Rietveld refinements give a clear picture of the aluminum intercalation induced phase transition process of Mo6S8. High resolution TEM further provided strong evidence of Al3+ intercalation and phase transition of Mo6S8. In light of the information gained from the Al3+ intercalation and deintercalation process, constant-current-constant-voltage charge and galvanostatic discharge technique was used to improve the cycling performance of Mo6S8. A 50% capacity increase was obtained with a high current density of 40 mA g-1. At last, we extended our cathode materials screening on other transition metal sulfides base on the previous results. We presented layered TiS¬2 and cubic Cu0.31Ti2S4 to be potential cathode materials for rechargeable Al-ion batteries. Layered TiS2 showed better electrochemical performance than Cubic Cu0.31Ti2S4. Moreover, we also demonstrated that the slow diffusion of Al3+ in the titanium sulfides crystal structure is the main obstacle to achieving high Al intercalation capacity through GITT analysis

Reversible Electrochemical Intercalation of Aluminum in Transition Metal Sulfides

Rechargeable battery technology has been one of the most exciting advancements in science and technology in the last several decades. Even though lithium ion battery technology has achieved great success in many fields, its wide deployment for large-scale energy storage is very questionable because of the limited resources of lithium. Therefore, alternative rechargeable battery technologies based on abundant elements need to be developed for sustainable electrochemical energy storage. Among all the potential candidates, battery systems based on aluminum as anode is particularly promising. In this thesis, we are dedicated to develop novel rechargeable Al-ion battery prototypes mainly focusing on cathode materials. Our achievement of discovering transition metal sulfides as promising cathode materials for rechargeable Al-ion batteries is pioneering. We first proposed Chevrel Phase Mo6S8 as intercalation-type cathode material for rechargeable Al-ion battery using ionic liquid electrolyte. We investigated the electrochemical properties as well as compositional properties of Chevrel Phase Mo6S8 as a cathode material. We believe it is the first reported intercalation-type rechargeable Al-ion battery prototype. We went further to probe the detailed intercalation process of Al3+ in Chevrel phase Mo6S8. High quality powder XRD data along with Rietveld refinements give a clear picture of the aluminum intercalation induced phase transition process of Mo6S8. High resolution TEM further provided strong evidence of Al3+ intercalation and phase transition of Mo6S8. In light of the information gained from the Al3+ intercalation and deintercalation process, constant-current-constant-voltage charge and galvanostatic discharge technique was used to improve the cycling performance of Mo6S8. A 50% capacity increase was obtained with a high current density of 40 mA g-1. At last, we extended our cathode materials screening on other transition metal sulfides base on the previous results. We presented layered TiS¬2 and cubic Cu0.31Ti2S4 to be potential cathode materials for rechargeable Al-ion batteries. Layered TiS2 showed better electrochemical performance than Cubic Cu0.31Ti2S4. Moreover, we also demonstrated that the slow diffusion of Al3+ in the titanium sulfides crystal structure is the main obstacle to achieving high Al intercalation capacity through GITT analysis

Below the 12-vertex: 10-vertex carborane anions as non-corrosive, halide free, electrolytes for rechargeable Mg batteries.

The development of practical Mg based batteries is limited by the lack of a library of suitable electrolytes. Recently a 12-vertex closo-carborane anion based electrolyte has been shown to be the first electrolyte for Mg based batteries, which is both non-corrosive and has high electrochemical stability (+3.5 V vs. Mg0/2+). Herein we show that smaller 10-vertex closo-carborane anions also enable electrolytes for Mg batteries. Reduction of the trimethylammonium cation of [HNMe31+][HCB9H91-] with elemental Mg yields the novel magnesium electrolyte [Mg2+][HCB9H91-]2. The electrolyte displays excellent electrochemical stability, is non-nucleophilic, reversibly deposits and strips Mg, and is halide free. This discovery paves the way for the development of libraries of Mg electrolytes based on more cost effective 10-vertex closo-carborane anions

Reversible Electrochemical Intercalation of Aluminum in Mo₆S₈

Reversible Electrochemical Intercalation of Aluminum in Mo₆S<sub>8</sub

The Spatial Correlation Network of China’s High-Quality Development and Its Driving Factors

The spatial correlation of high-quality development has emerged as a crucial approach to tackling economic polarization. This study assesses the level of high-quality development in China from 2006 to 2020, utilizing the new development concept. Social network analysis is employed to explore the spatial correlation mechanism of high-quality development. The quadratic assignment procedure (QAP) is used to analyze the driving factors that impact spatial correlation systems from both internal and external perspectives. The research indicates that China’s level of high-quality development has consistently improved between 2006 and 2020. The spatial correlation network has increasingly become more connected, while the eastern provinces, specifically Shanghai and Beijing, have a significant influence in the spatial correlation of high-quality development. However, the central and western provinces, such as Xinjiang and Inner Mongolia, occupy peripheral positions in this network. Furthermore, clear spatial correlation and spillover effects are apparent among the dimensions. From an internal standpoint, innovation, greenness, openness, and sharing are the key factors that contribute to establishing a high-quality development network. In addition, external elements such as financial development, social consumption, and convenient transportation are interconnected in space, which promote the creation of a high-quality development network. Local protectionism and population concentration impede the establishment of a high-quality development network

Colloidal Synthesis of Silicon–Carbon Composite Material for Lithium‐Ion Batteries

We report colloidal routes to synthesize silicon@carbon composites for the first time. Surface-functionalized Si nanoparticles (SiNPs) dissolved in styrene and hexadecane are used as the dispersed phase in oil-in-water emulsions, from which yolk-shell and dual-shell hollow SiNPs@C composites are produced via polymerization and subsequent carbonization. As anode materials for Li-ion batteries, the SiNPs@C composites demonstrate excellent cycling stability and rate performance, which is ascribed to the uniform distribution of SiNPs within the carbon hosts. The Li-ion anodes composed of 46 wt % of dual-shell SiNPs@C, 46 wt % of graphite, 5 wt % of acetylene black, and 3 wt % of carboxymethyl cellulose with an areal loading higher than 3 mg cm-2 achieve an overall specific capacity higher than 600 mAh g-1 , which is an improvement of more than 100 % compared to the pure graphite anode. These new colloidal routes present a promising general method to produce viable Si-C composites for Li-ion batteries