Electrochemical signals can be obtained without obstacle of solution resistance when solution contains indifferent electrolytes. But, recently, some novel electrochemical technologies prefer salt free or hypohaline cell. In which exemplified by: salt free electrolysis, electric double layer capacitor etc. Unfortunately, electrochemical behavior at low ionic concentration is difficult to be observed because current-voltages are complicated by solution resistance. The difficulty is predicted to be overcome by use of large multi-charged ions such as polyoxometalate and ionic polymers during...