Electrochemical properties of carbonyl substituted phthalocyanines as electrode materials for lithium-ion batteries

Tetra-carboxylic acid lithium phthalocyanine (t-CAL-Pc) and tetra-(di-acyl) substituted phthalocyanine (t-DA-Pc) were prepared to construct a new type of organic electrode material. The electrochemical properties were investigated and the effects of group substitution on the electrochemical properties were analyzed for the first time. The results indicated that after the hydrogen in the carboxyl group was substituted by lithium and a di-acyl group respectively, the cyclic stability performance of phthalocyanines (t-CAL-Pc and t-DA-Pc) was improved and the irreversible capacities were reduced. The capacities can still remain at 169 mA h g^-1 after 100 cycles for t-CAL-Pc and 241 mA h g^-1 after 200 cycles for t-DA-Pc, and the initial columbic efficiencies were 94% and 97% respectively, which were much higher than that of 70% for tetra-carboxyl phthalocyanine (t-C-Pc).