Preparation of Energy-Storing Current Collectors Based on Si-incorporated Carbon Nanotube Films

Abstract

The rapid growth of the electric vehicle (EV) industry in recent years has further intensified the demand for high-performance lithium-ion batteries (LIBs), making the improvement of cell energy density an increasingly important challenge in the development of next-generation energy storage technologies.Although most strategies have focused on increasing the capacity of active materials, minimizing the mass of inactive components that do not directly participate in electrochemical reactions has recently emerged as an equally effective approach to improving cell-level energy density. Reducing the inactive mass increases the proportion of active materials in the total electrode weight, thereby enhancing both the gravimetric energy efficiency of the cell. The copper (Cu) foil current collector constitutes a considerable portion of the total electrode weight despite being electrochemically inert. Replacing it with lightweight, conductive, and flexible materials therefore represents a promising route to higher energy density. Carbon nanotubes (CNTs) have attracted increasing attention as next-generation current collectors owing to their excellent electrical conductivity, outstanding mechanical strength, and extremely low density. CNT films fabricated via a direct spinning process possess a highly interconnected fibrous network with tunable alignment and porosity, which enables efficient electron transport and provides a favorable structure for the uniform dispersion and stable incorporation of high-capacity active materials such as silicon (Si). These structural advantages render CNT films excellent candidates for multifunctional electrodes that combine electrical conduction, mechanical reinforcement, and electrochemical activity. Lightweight CNT film current collectors were fabricated by the direct spinning method and subsequently integrated with Si active material to form high-energy-density anodes. The effects of CNT fiber orientation and film density on electrochemical performance were systematically investigated. Morphological and structural characterizations were assessed using field-emission scanning electron microscopy (FE-SEM), and Raman spectroscopy, while electrochemical behaviors were evaluated through galvanostatic charge–discharge tests, cyclic voltammetry (CV), rate capability, and electrochemical impedance spectroscopy (EIS). These analyses elucidated the relationship between the CNT network architecture, charge-transfer pathways, and the resulting energy storage characteristics. The CNT film current collector, featuring both high electrical conductivity and intrinsic electrochemical activity, effectively contributed to charge storage while maintaining mechanical integrity and ultralow density. This combination of properties allows the CNT film to function not only as a conductive scaffold but also as an electrochemically responsive component within the electrode system. The developed CNT-based current collector therefore shows great promise for achieving a remarkable enhancement in cell-level energy density. These findings highlight a practical and scalable design strategy for next-generation lithium-ion batteries and related high-performance energy-storage technologies.