Zhirong Zhao-Karger

The kinetic properties of Mg(BH4)2 infiltrated in activated carbon.

A wet incipient impregnation procedure was developed to infiltrate Mg(BH4)2 into the voids of pre-treated activated carbon with a pore diameter of < 2 nm. The thermal data of the composite material showed a strong broadening of the signals. The peak decomposition temperature was shifted to lower values by the infiltration. A Kissinger analysis of bulk Mg(BH4)2 and the nanocomposite revealed a high activation barrier for the first step of the dehydrogenation of the bulk material, which was lowered by a factor of two for the nanoconfined hydride.

Bisamide based non-nucleophilic electrolytes for rechargeable magnesium batteries

Non-nucleophilic electrolytes with outstanding electrochemical performances for magnesium batteries have been synthesized through the reaction between a bisamide magnesium and a Lewis acid in an aprotic solvent. High anodic stability, good ionic conductivity, excellent cycling efficiency and the feasibility of the preparation make the in situ generated electrolyte very promising for the potential application in rechargeable magnesium batteries.

Metal Oxychlorides as Cathode Materials for Chloride Ion Batteries

A key challenge of chloride ion batteries is to develop cathode materials that are stable in the electrolytes. Metal oxychlorides are presented as such a cathode material. The electrochemical performance and the reaction mechanisms of the BiOCl and FeOCl cathode were investigated. Both cathodes showed reversible reactions, including a major conversion reaction and a minor intercalation process, by chloride ion transfer during cycling.

Performance study of magnesium–sulfur battery using a graphene based sulfur composite cathode electrode and a non-nucleophilic Mg electrolyte

Here we report for the first time the development of a Mg rechargeable battery using a graphene-sulfur nanocomposite as the cathode, a Mg-carbon composite as the anode and a non-nucleophilic Mg based complex in tetraglyme solvent as the electrolyte. The graphene-sulfur nanocomposites are prepared through a new pathway by the combination of thermal and chemical precipitation methods. The Mg/S cell delivers a higher reversible capacity (448 mA h g(-1)), a longer cyclability (236 mA h g(-1) at the end of the 50(th) cycle) and a better rate capability than previously described cells. The dissolution of Mg polysulfides to the anode side was studied by X-ray photoelectron spectroscopy. The use of a graphene-sulfur composite cathode electrode, with the properties of a high surface area, a porous morphology, a very good electronic conductivity and the presence of oxygen functional groups, along with a non-nucleophilic Mg electrolyte gives an improved battery performance.

Altered reaction pathways of eutectic LiBH4–Mg(BH4)2 by nanoconfinement

The effects of nanoconfinement on the dehydrogenation rate and reaction pathways of the eutectic LiBH4–Mg(BH4)2 have been comprehensively investigated. By means of thermal analysis, mass spectroscopy and solid state 11B MAS NMR, it has been revealed that the multistep thermal decomposition pattern of the binary LiBH4–Mg(BH4)2 has been altered in a two-step reaction and the desorption kinetics has also been significantly improved after infiltration. The formation of diborane and stable MnB12H12 intermediates of the bulk LiBH4–Mg(BH4)2 has been found to be inhibited by nanoconfinement.

Magnesium Anode for Chloride Ion Batteries

A key advantage of chloride ion battery (CIB) is its possibility to use abundant electrode materials that are different from those in Li ion batteries. Mg anode is presented as such a material for the first time and Mg/C composite prepared by ball milling of Mg and carbon black powders or thermally decomposed MgH2/C composite has been tested as anode for CIB. The electrochemical performance of FeOCl/Mg and BiOCl/Mg was investigated, demonstrating the feasibility of using Mg as anode.

A new class of non-corrosive, highly efficient electrolytes for rechargeable magnesium batteries

Fluorinated alkoxyborate based magnesium electrolytes exhibit a high anodic stability, high ionic conductivity and high coulombic efficiency of magnesium deposition. Owing to the non-corrosive, chemically stable nature and the robust, economic synthesis, this design concept of ion conducting salts opens a promising avenue towards the realization of high-energy magnesium batteries.

Vanadium oxychloride/magnesium electrode systems for chloride ion batteries

We report a new type of rechargeable chloride ion battery using vanadium oxychloride (VOCl) as cathode and magnesium or magnesium/magnesium chloride (MgCl2/Mg) as anode, with an emphasis on the VOCl-MgCl2/Mg full battery. The charge and discharge mechanism of the VOCl cathode has been investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical measurements, demonstrating the chloride ion transfer during cycling. The VOCl cathode can deliver a reversible capacity of 101 mAh g(-1) at a current density of 10 mA g(-1) and a capacity of 60 mAh g(-1) was retained after 53 cycles in this first study.

Fabrication of porous rhodium nanotube catalysts by electroless plating

A versatile electroless plating procedure for the fabrication of rhodium nanomaterials was developed, leading to deposits consisting of loosely agglomerated metal nanoparticles. By using carbon black as the substrate, supported rhodium nanoparticle clusters were obtained. In combination with ion track etched polymer templates, the deposition protocol allowed the first direct synthesis of rhodium nanotubes. Polymer dissolution provided access to well defined, supportless and free-standing rhodium nanotubes of nearly cylindrical shape, 300 nm opening diameter, 28 μm length and 50 nm wall thickness. The characterization by SEM, TEM, EDS and XRD confirmed the purity of the deposit, displayed a small particle size of approximately 3 nm and revealed gaps in the range of a few nanometers between the rhodium particles. BET analysis verified the presence of pores of <5 nm. To evaluate the electrocatalytic potential of the rhodium nanotubes, they were applied in the amperometric detection of hydrogen peroxide. Compared to classical nanoparticle-based sensing concepts, improved performance parameters (sensitivity, detection limit, and linear range) could be achieved.

VOCl as a Cathode for Rechargeable Chloride Ion Batteries.

A novel room temperature rechargeable battery with VOCl cathode, lithium anode, and chloride ion transporting liquid electrolyte is described. The cell is based on the reversible transfer of chloride ions between the two electrodes. The VOCl cathode delivered an initial discharge capacity of 189 mAh g(-1) . A reversible capacity of 113 mAh g(-1) was retained even after 100 cycles when cycled at a high current density of 522 mA g(-1) . Such high cycling stability was achieved in chloride ion batteries for the first time, demonstrating the practicality of the system beyond a proof of concept model. The electrochemical reaction mechanism of the VOCl electrode in the chloride ion cell was investigated in detail by ex situ X-ray diffraction (XRD), infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results confirm reversible deintercalation-intercalation of chloride ions in the VOCl electrode.