Effect of SiO2/Al2O3 ratio on the electrochemical performance of amorphous zeolite loaded with cobalt oxide grown via steam-assisted crystallization method

Improving the performance of a supercapacitor is one of the main approaches to solve the energy shortage problem. Electrode material is one of the key components limiting the efficiency of a supercapacitor. Discovering, tuning, and improving electrode materials are very important. This work reports the effect of SiO2/Al2O3 ratio on electrochemical performances of amorphous zeolites ZSM5 (AZ) and H-ZSM5 (H-AZ) loaded with cobalt oxide. Two SiO2/Al2O3 ratios (1 = 6.2 and 2 = 8.3) of AZ(1), AZ(2) and H-AZ(1), H-AZ(2) were synthesized by a facile impregnation method. Then, controlled masses of cobalt oxide were introduced to enhance the supercapacitive performances of the amorphous zeolite. Investigation of the SiO2/Al2O3 ratio in the cobalt oxide/zeolite composite (Co/AZ and Co/H-AZ) was carried out to unveil its effect on the electrochemical properties. Worthy of note is the fact that the resulting electrode materials exhibited supercapacitive behavior that is effective over a potential window ranging from 0 to 0.5 V in potassium hydroxide (1 M KOH) aqueous electrolyte. Results from Galvanometry Charging and Discharging (GCD) analyses show that the modified Ni-foam electrodes loaded with Co/H-AZ(1) and Co/H-AZ(2) are capable of delivering a relatively high specific capacity from 45.97 mA h g(-1) to a high value of 72.5 mA h g(-1) at 1 A g(-1) and Ni-foam electrodes loaded with Co/AZ(1) and Co/AZ(2) exhibited values from 26 mA h g(-1) to 52.83 mA h g(-1) respectively. It is clearly shown that, when the mass ratio SiO2/Al2O3 increases, the specific capacity increases as well. It was also noticed that after 2000 cycles, Co/H-AZ(1) and Co/AZ(1) have a poor coulombic efficiency while Co/H-AZ(2) and Co/AZ(2) exhibited 98% for coulombic efficiency. Finally, this study shows that to fabricate high performance supercapacitors with amorphous zeolite loaded with cobalt oxide, one should keep the ratio of SiO2/Al2O3 as high as possible during synthesis.

Automated summary

This study investigates the effect of the SiO2/Al2O3 ratio on the electrochemical performance of the aluminum silicate/cobalt oxide composite. The results show that the specific capacity increases as the SiO2/Al2O3 ratio increases. It was also found that after 2000 cycles, Co/H-AZ(1) and Co/AZ(1) exhibit poor coulombic efficiency, while Co/H-AZ(2) and Co/AZ(2) exhibit a coulombic efficiency of 98%.