Wang Jiulin

Review of Sulfur-Based Cathodes for High Performance Lithium Rechargeable Batteries

The preparation, characteristics and electrochemical performances of the sulfur-based cathode materials in lithium/sulfur batteries are reviewed in this paper. The elemental sulfur cathode material is briefly introduced. The structural designs, preparation processes, reaction mechanisms, and charge/discharge properties of organic sulfide, sulfur-porous carbon and sulfur-polymer composites as cathode materials are systematically discussed and problems associated with these materials are also analyzed. In addition, the research and application of lithium sulfides as cathode materials are also outlined. Finally, the further development of sulfur-based cathode materials and the commercialization of lithium/sulfur batteries are discussed.

Composite Cathode Structure and Binder for High Performance Lithium-Sulfur Battery

Ball milling in combination with heat treatment was used to prepare sulfur-based composite cathode materials incorporating multi-walled carbon nanotubes (MCNTs) for Li-S battery. The structure and morphology of the as-prepared cathode materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of MCNT content and binder type on the capacity,cyclability and self-discharge behavior of a sulfur-based cathode were systematically investigated. Results show that the appropriate amount of MCNTs is 5%-8% (w,mass fraction) and the use of β-cyclodextrin as a water-soluble binder to fabricate the cathode results in the best electrochemical performance. When the Li-S battery was half charged at room temperature,there was almost no self-discharge during storage for 30 d. The charging capacity was 687.7 mAh.g-1 during the 1st cycle and 623.8 mAh.g-1 during the 100th cycle for the cathode at a current rate of 0.1C. Therefore,90.7% of the capacity was retained.

Effects of Current Collectors on the Electrochemical Performance of Electrolytes for Rechargeable Magnesium Batteries

The effects of metal(platinum,nickel,stainless steel(SS),copper and aluminum) and carbon(carbon fiber,graphite foil and carbon cloth) current collectors on the anodic stability and magnesium deposition-dissolution of the electrolytes(Mg(AlCl2BuEt)2/THF and(PhMgCl)2-AlCl3/THF) for rechargeable magnesium batteries were studied by cyclic voltammetry and constant current deposition-dissolution.Nickel,SS,copper and aluminum current collectors corrode on charging.Nickel and SS exhibit higher stability than the other metals,and can be used as the current collector for the cathode material with a charging voltage under 2.1 V(vs Mg/Mg2 +).Copper is suitable for the cathode with a charging voltage under 1.8 V(vs Mg/Mg2+).Furthermore,carbon current collectors have higher anodic stability than metals.Carbon cloth is appropriate for the cathode material with a charging voltage under 2.25 V(vs Mg/Mg2+) in Mg(AlCl2BuEt)2/THF and 2.95 V(vs Mg/Mg2+) in(PhMgCl)2-AlCl3/THF.

Benzenethiolate-Based Solutions for Rechargeable Magnesium Battery Electrolytes

The benzenethiolate-based solutions (RSMgCl)n-AlCl3/tetrahydrofuran (THF) (R=4-methylbenzene, 4-isopropylbenzene, 4-methoxybenzene; n=1, 1.5, 2, respectively) were obtained by the simple reaction of benzenethiol compounds with the Grignard reagent C2H5MgCl/THF and AlCl3 in THF, and the electrochemical performance as the rechargeable magnesium battery electrolytes are reported. First, 4-methyl-benzenethiolate magnesium chloride (MBMC)/THF, 4isopropylbenzenethiolate magnesium chloride (IPBMC)/THF, and 4methoxybenzenethiolate magnesium chloride (MOBMC)/THF solutions (termed as RSMgCl/THF) were synthesized by the reaction of 4-methylbenzenethiol, 4isopropylbenzenethiol, and 4methoxybenzenethiol compounds, respectively, with C2H5MgCl/THF via a hydrogen metal-radical exchange with rapid evolution of ethane gas. Furthermore, (RSMgCl)n-AlCl3/THF solutions were obtained by the reaction of RSMgCl/THF with AlCl3/THF at different molar ratios of RSMgCl:AlCl3. The benzenethiolate-based solutions as electrolytes for rechargeable magnesium batteries were characterized in term of anodic stability and reversibility of magnesium deposition-dissolution using cyclic voltammetry and galvanostatic charge/discharge techniques. Furthermore, the compatibility of the solutions with Mo6S8 cathode material was verified using coin cells with a Mo6S8 cathode, Mg anode, and benzenethiolate-based electrolyte. It is concluded that both the substituents on benzenethiol and the ratio of RSMgCl:AlCl3 have an effect on the electrochemical performance. 0.5 mol∙L-1 (IPBMC)1.5-AlCl3/ THF shows the best electrochemical performance with 2.4 V (vs Mg/Mg + ) anodic stability, a low voltage for magnesium deposition-dissolution, a high cycling reversibility, and good compatibility with the Mo6S8 cathode. Moreover, the air insensitive character and easy preparation make it a promising candidate for rechargeable battery electrolytes. 311 Acta Phys. -Chim. Sin. 2014 Vol.30