Highly flexible flyash/multiwalled carbon nanotubes composite paper: A sustainable electrode for new generation Li-ion batteries

Flexible energy storage devices have been the focus of much research and development as potential sources of energy for portable electronic devices. However, designing an innovative electrode structure that is cost-efficient, sustainable, and resource-efficient poses a significant challenge to the advancement of next-generation flexible-energy storage materials. Flyash, as an industrial waste, can be used as a potential electrode material because of its low cost and the presence of various metal oxides, especially silicon-based materials. Using a low-cost and binder-free vacuum filtration method, we present a facile method for forming a very stable porous architecture of flyash and multiwalled carbon nanotubes (MWCNTs). Here, the performances of flyash/MWCNT paper anodes prepared via acid-reflux and simple stirring methods are compared to determine the influence of both methods on the electrochemical properties of the anode. When using a current density of 0.1 A/g for up to 300 cycles, the acid-refluxed and flyash blended MWCNTs composite paper anodes exhibit a specific capacity of 290 mAh/g and 272 mAh/g, respectively, with over 98% coulombic efficiency. The highly porous and interconnected MWCNTs conducting network makes it easier for Li + ions to penetrate and come into direct contact with the metal oxides found in flyash. As a result, the composite paper shows a high specific capacity that holds steady over extended cycles and impressive rate capabilities for Li storage. The study introduces a novel approach to creating flexible composite papers using flyash and MWCNTs, exhibiting a high specific capacity and excellent coulombic efficiency, emphasizing the environmentally friendly disposal and reuse of low-cost flyash as an anode material. • A flexible flyash/MWCNT paper electrode is fabricated. • Flyash, a low-cost waste, is used as the anode material. • The electrode accommodates volume changes during cycling. • Metal oxides in flyash enhance lithium storage capacity. • Interconnected MWCNT network improves Li-ion diffusion and stability.