Electrical energy storage systems have attracted much more attentions as the ideal technology to overcome the drawbacks associated with the storage and use of intermittent renewable energies, such as solar and wind. These systems are not only able to provide energy where and when it is required but also reduce the high capital cost of managing peak demands on the grid as well as large investments in grid infrastructures. Cost, reliability and safety are the most important factors to be considered to develop these systems. Recently, several battery technologies, such as redox flow, sodium sulfur, or lithium ion, have been proposed as possible systems for large-scale stationary energy storage, but they suffer from low charging rates, high operating temperatures, the use of hazardous or flammable materials in their components, and/or high costs. In particular, for traditional Li ion battery, the high cost and poor safety owing to the use of Li and flammable non-aqueous electrolytes limits its application in the field of grid scale energy storage. Therefore, recently, in place of Li ion battery, aqueous rechargeable battery, like zinc ion battery, has become more attractive because of its low cost and high safety. However, the disadvantages, such as the low energy density and poor cycling stability, seem to be the biggest issues to be addressed.
Here, we introduced a kind of cathode material and demonstrated a new zinc-ion battery systems with zinc foil as anode materials. For this system, the open circuit voltage (OCV) was around 1.5 V and the energy density could achieve as high as around 170 mAh/g at 0.5C. Also, no zinc dendrites were found at the anode side, and the coulomb efficiency (CE) was almost close to 100%. No significant capacity fading was observed over 1000 cycles at 5C. The different water-soluble zinc salts were applied to this system, which greatly affected the battery performances. The mechanisms behind that were investigated in detail.