High-Efficiency Electrocatalyst Phthalocyanine in Li/SOCl₂ Batteries: From Experimental to Theoretical Investigation

Abstract

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.

Transforming a Primary Li-SOCl2 Battery into a High-Power Rechargeable System via Molecular Catalysis

“…Further reduction at the carbon cathode is hindered by the dimerization of the radical, which is the rate-limiting step (a detailed analysis is provided in Supporting Information 1.4). Note that previously reported catalysts, such as metal phthalocyanines, − enhance the discharge performance by improving electron transfer via the delocalized π-electron system and alleviating dimerization via coordination effects between the phthalocyanines and radicals. I 2 fundamentally changes the intermediate, as shown in eqs –, and is thus significantly different from traditional catalysts used in Li-SOCl 2 cells.…”

“…Another bottleneck limiting further application of Li-SOCl 2 batteries is their low-rate discharge performances. In recent decades, molecular catalysts such as transition metal-phthalocyanine complexes ,− have been employed in Li-SOCl 2 systems with the aim of enhancing electron transfer and/or avoiding radical dimerization during discharging. However, the challenge remains as the rate-determining step of discharge is unchanged.…”

The Impact of Temperature on the Performance and Reliability of Li/SOCl2 Batteries

“…Long-term storage of Li/SOCl 2 batteries results in the formation of a LiCl passivation layer on the surface of the electrode. This passivation layer acts as a physical barrier between the Li metal negative electrode and the electrolyte, protecting the Li metal negative electrode [19]. The EIS curves under this condition are represented by the blue curves in Figure 14a-c.…”

Stable and improved voltage plate of Li/SOCl2 battery using carbon electrodes with active carbon

“…A lot of works related to using metal porphyrin, phthalocyanine as well as the other N, S containing complexes as the catalysts to improve the performance of batteries on the basis of the enhancement of the reduction of SOCl 2 , as well as the formation a LiCl loose film to provide a higher voltage with a longer discharge time [10][11][12][13][14][15]. The reduction reaction of SOCl 2 happened in the surface of acetylene carbon black, as the predominant material of the carbon cathode of Li/SOCl 2 batteries.…”