In the CV test chart, the distance between the oxidation peak and the reduction peak can also reflect the reversibility of the battery. Compared with the huge gap between oxidation peak and reduction peak in Fig. (a) which indicates the poor reversibility, the situations in Fig. ) and (d) are improved. The gap between the oxidation peak and the reduction peak in Fig. ) is only about 0.16V and in Fig. ) is about 0.14V. The narrow gap between the peaks means better reversibility of the NHPI cathode in acidity adjusted electrolyte. In Fig. and, there is only one peak occurs in the charging process, the absence of the small peak before the oxidation process indicates that the decrease of the acidity of the environment can prevent the side reaction and optimize the battery performance. Furthermore, as the cycle progresses, the area of the oxidation peak and the reduction peak increase gradually. This may be due to the activation during the charge and discharge of NHPI the battery or the better electrolyte contact with the increasing of the cycle numbers. In other words, in these six cycles, the area of the oxidation peak is not reduced in Fig. ) and (d), indicating that NHPI in electrolyte with lower pH exhibits better performance in the oxidationreduction cycling behaviour. This may be due to the inhibition of the decomposition of NHPI by the presence of hydrogen ions. In the decomposition of NHPI, two molecules of PINO produce an NHPI development and a molecular intermediate under the action of a hydrogen ion. The intermediate product will react with another NHPI molecule to form an oligomer. This reaction is the main cause of the decrease in battery active substances. Under strong acidic conditions, the presence of excess hydrogen ions can convert both molecules of PINO into NHPI without forming intermediates, thereby inhibiting the formation of oligomers and improving the stability of NHPI. In order to evaluate the performance of NHPI-Zn batteries in these three electrolytes, constant current charge-discharge (Galvanostatic Cycling with Potential Limitation, GCPL) cycles were performed with a two-electrode setup. Figure shows the profiles of 5 cycles of GCPL tests of NHPI-Zn batteries in electrolytes with different pH values. The platform in the curve represents the constant current charging and discharging reactions in the battery. During the charging process of the battery, when the oxidation potential is reached, NHPI will be oxidized to PINO on the cathode, and the electrical energy is converted into chemical energy stored in the battery, so the voltage does not change under constant current charging and expressed as platform in the profiles. And in the process of discharging, the platform represents the transformation of chemical energy into electrical energy. After all of the chemical energy is turned into electrical energy and released, the voltage of the battery starts to decrease until zero. In constant current charging and discharging, the length of the discharge platform is less than the length of the charging platform due to the presence of battery impedance. The longer the length of the discharge platform, the larger the discharge capacity of the battery. In Fig. (a), after a long-time charging process, the discharge platform of NHPI/Zinc battery in 1MZnSO 4 electrolyte is almost non-existent. This shows that even after about one hour of charging, the discharge capacity of the battery is still very poor. During the discharge process, the voltage drops directly without passing through the platform, indicating that no chemical energy is converted into electrical energy. This may be due to the NHPI's decomposition. After charging, NHPI is oxidized to PINO, and a reaction occurs between every two molecules of PINO to produce an intermediate product that reacts with the remaining NHPI and produces an oligomer. The oligomer is not electrochemically active and cannot be broken down into NHPI again, so the reaction will irreversibly greatly reduce the amount of active material in the battery. Thus, in Fig. , not only almost no discharge platform, and with the number of cycles increases, the charging platform is gradually attenuated, which is consistent with our previous CV results (Figure ).