The vanadium redox flow battery energy storage system that developed independently by 303 group has been automatically and continuously operated for 105 days, that means ,over 2500 hours, and without any technical problem. The demonstration system consists three parts: kilowatt cell stack, system control module and LED screen. At night the system can store energy, during the day, it can applied in the LED power supply.The energy efficiency of VRB is up to 87%, and without degradation.

The Vanadium redox flow battery is an energy storage device, consisting of cell stack, electrolytes, electrolyte storage & delivery systems and system control module. The cell stacks has consists of tens to hundreds single cell, assembled in the filter press mode. The vanadium electrolytes are stored in separate large electrolyte tanks outside the cell stack, and are pumped into the cell with external pumps, cause the electrochemical oxidation and reduction reactions, to achieve charge and discharge process. While the power rating depends on the size of the electrode area and number of the cell stacks; the cells in the battery are electrically connected in series, but in most designs the electrolyte flows through the cells in parallel. The energy rating depends on the size of the electrolyte tanks, that means, the energy and power ratings of flow batteries are independent, therefore, the output power and storage capacity can be designed independently. Compared with other chemical energy storage technology, the flow batteries have several advantages over conventional technology: high energy efficiency, high electrical storage capacity up to 100 MWh; capacity and power are independent, flexibility design system; high reliability, deep discharge; system site free; most component materials of the battery can be recycled; system operation& maintenance costs are low; especially safe and environmentally friendly. For these outstanding advantages, VRB is one of the first selections for large scale energy storage technology.

Our research for VRB have been received the financial support from “863” programme establish by national technical department, Dalian BoRong Co.Ltd and Dalian Economic Committee. Beside above progress，we also make progress in battery energy storage capacity degradation mechanism research, how to improve the battery capacity stability and design&optimization for high power cell stack. Recently, the charge and discharge conversion efficiency of the third generation 5KW cell stack have up to 80%.

The above research results are significant for promote the VRB practicability process.

2007.10.17