With the development of technology and consumers' higher pursuit of quality of life, many electronic products such as laptops, watches and headphones tend to be smaller, lighter and more flexible. These portable electronic devices are more convenient to carry and meet the modern people's living requirements. Furthermore, in addition to the electronic products used in daily life, some medical devices have become more compact and portable. Factors such as the aging of the global population, the improvement of people's living standards and the increasing demand for medical services in remote areas are driving the transformation of traditional medical methods. Mobility and portability have gradually become the key factors affecting the medical electronics industry. Electronic thermometer, portable blood glucose meter, portable ultrasound equipment, wearable electrocardiograph, cardiac pacemaker and so on. All of these portable devices require stable power supply and small battery volume. Compared with flow batteries or cylindrical dry batteries, coin battery with small volume is suitable to be applied in small precision device. Coin batteries come in many sizes and vary greatly in diameter and thickness. Among the commercial coin batteries, the largest market share is the lithium battery. Although lithium batteries can provide higher voltages, non-aqueous organic electrolytes in lithium batteries have always been a safety hazard. Due to the flammability of organic electrolytes, lithium batteries can cause explosions or fires during production, transportation and use. Furthermore, the cathode in Li-ion battery is always metal oxide, the production of Li-ion will consume precious metal resources. Recently, research on organic radical batteries using TEMPO or NHPI as cathode has received a lot of attention. As a cheap, abundant, non-toxic, less environmentally friendly material, TEMPO and NHPI are popular metal-free cathode materials. There are many reports about using TEMPO as cathode active materials and got satisfied results. The research about the appliance of NHPI in organic radical battery is rare, but compared with TEMPO, NHPI exhibits lower cost and higher redox potential. Moreover, our team succeed in using NHPI as cathode material in a semi-aqueous flow battery. Thus, in this research we studied the properties of NHPI/Zinc coin battery and found that in acidity adjusted electrolyte the NHPI/Zinc battery has nearly 80% columbic efficiency. This result highlights the value of organic radical material in the fibiracation of battery. And the electrolyte used in this system is aqueous zinc sulphate solution, avoiding the safety hazard caused by organic electrolyte mentioned above. Figure : Electrolyte in different acidity gradients used in experiment.