| Magnesium has similarity with lithium in many aspects, such as ionicradius and chemical properties. In addition, magnesium is relativelyinexpensive, environmentally friendly and safe to handle. The properties ofmagnesium make it a natural choice for use as anode material inrechargeable batteries because magnesium has large theoretical specificcapacity, it may provide a considerably higher energy density than thecommonly used lead-acid and nickel-cadmium systems. So rechargeablemagnesium batteries may be a promising electrochemical power source.Herein, the effects of different current collectors on the rechargeablemagnesium battery electrolytes （Mg（AlCl2BuEt）2/THF and（PhMgCl）2-AlCl3/THF） were researched. Nickel（Ni）, stainless steel（SS）,copper（Cu） and aluminum（Al） occur corrosion upon charging process,which limits the application of the electrolytes at higher potentials. Ni orSS can be used as the current collector for the cathode materials with acharging voltage under2.1V （vs. Mg）, Cu is suitable for the cathodematerials with a charging voltage under1.8V （vs. Mg）, and Al is notprobable as current collector for rechargeable magnesium batteries due toits bad stability. Furthermore, carbon paper current collectors have a higherstability than metals and can be used as the current collectors forhigh-voltage cathode materials.In addition, we prepared several novel cathode materials and exploredtheir electrochemical performance for rechargeable magnesium batteries.Poly （2,2,6,6-tetramethylpiperidinyloxy-4-ylmethacrylate） （PTMA）/graphene composite was synthesized in which thethree-dimensional graphene networks improve the electronic conductivityof composites and the radical affords for the redox reaction. The materialexhibits a high discharge capacity of209.8mAh·g-1. PTCDA withcarbonyl shows the first discharge capacity of207.1mAh·g-1. Both thematerials exhibit poor cycling performance. The capacity fading may becaused by the dissolution and decomposition of organic compounds. Morecathode materials for rechargeable magnesium batteries will be found byreasonable design of the organic compound.Carbyne polysulfide was prepared by co-heating carbon containingcarbyne moieties and element sulfur. In this material, conducting polymercarbyne was used as a stable backbone to provide electric conductingchannels to offer good electric conductivity, and polysulfide lines as sidelines to offer high specific capacity. The material exhibits a high dischargecapacity of327.7mAh·g-1. The capacity retention could be furtherimproved with more suitable current collector and electrolyte.3D ordered macropous Mg1.03Mn0.97SiO4was prepared with PScolloidal template. Different precursor components affect the structure ofthe final product. Higher temperature is needed to get pureMg1.03Mn0.97SiO4when using acetates as precursor and it’s difficult to keepthe porous structure. Crystalline Mg1.03Mn0.97SiO4can be synthesized atlower temperature with nitrate precursor, and the ordered macropousstructure can be kept well. The3D ordered macropous Mg1.03Mn0.97SiO4exhibits the specific capacity of71.4mAh·g-1, higher than the bulkMg1.03Mn0.97SiO4. The better electrochemical performance is caused by itslarge porosity and accessible surface area that facilitate electrolytepenetration and the thin wall which decreases the diffusion distance ofMg2+. |
PDF Full Text Request