Increase of gamma-Fe2O3/CNT composite quantum capacitance by structural design for performance optimization of electrode materials

摘要

Performance optimization of electrode materials for lithium-ion batteries is one the most important scientific problems. In this paper, we suggest structural design of gamma-Fe2O3/CNT composite for increase of its quantum capacitance that is required by modern energy storage devices capable of quick transfer or accumulation of energy and ensuring long-term autonomous operation. For this goal, we investigate the specific quantum capacitance of the gamma-Fe2O3/CNT composites with a different content of maghemite by quantum chemical methods. The content of maghemite is varied by length of CNTs as well as by number of gamma-Fe2O3 unit cell and equals to 13.71%, 20.74%, 26.69%, and 34.30%. It is found that the quantum capacitance grows with increasing maghemite concentration. Calculations show that the value of QC at the Fermi level for gamma-Fe2O3/CNT is correlated with the theoretical specific capacity of the material. Proposed in this work approach to calculating the quantum capacitance with further analysis of its dependence on voltage can be an effective tool for optimizing the content of the composite with the aim of balancing the Faradaic and non-Faradaic component of its functional activity.