Li/SOCl2 batteries, which are used in various fields due to theirs easy-carry and brilliant electrochemical properties, have attracted much research. However, the existence of the voltage hysteresis has limited further practical application of this tiny device. Herein, three series of nineteen kinds of metal phthalocyanine electrocatalysts with excellent electronic conductivity were synthesized to improve Li/SOCl2 battery performance. The structure of the catalysts was verified by infrared spectroscopy, ultraviolet-visible spectroscopy, thermogravimetric analysis, and elemental analysis, and these materials were used to develop the discharge time, output voltage, and discharge capacity of the Li/SOCl2 battery. With the addition of the phthalocyanine, the discharge time of the Li/SOCl2 battery lengthens by approximately 20%, and the voltage can be increased by 0.02∼0.20 V. In addition, the actual battery capacity can also be raised by 20∼50%. Density functional theory was used to calculate the relationship between the metal center and catalytic activity and the results are in good agreement with the experimental which implies the electron density of the center metal is the key point in the electrocatalyst reaction.