Enhancing tin foil anodes in lithium-ion batteries through carbon nanotube integration via rolling technique

Abstract

In this study, we propose the use of multi-walled carbon nanotubes (MWCNTs) combinded with accumulative roll bonding technique to enhance the performance of Sn foils as anodes in lithium-ion batteries. Increasing the amount of CNTs reduces the grain size of Sn, which leads to an increase in hardness. As the CNT content increases from 0 to 2.2 wt%, several electrochemical improvements are observed: decreased nucleation overpotential, enhanced Coulombic efficiency, reduced overpotential, lowered charge transfer resistance, and increased lithium-ion diffusivity. These combined effects synergistically enhance the capacity of the anode. The benefits of incorporating CNTs into Sn can be attributed to two main factors: (1) the increased grain boundaries, dislocations, and CNTs provide more active sites for (de)lithiation and facilitate faster lithium-ion diffusion paths; (2) the improved strength resulting from grain refinement and CNT reinforcements helps maintain structural integrity during the formation and growth of high-density pores over multiple cycles. Although the addition of CNTs enhances capacity up to a content of 0.9 wt%, further additions result in a stagnation in capacity enhancement. Furthermore, when the CNT content exceeds 0.6 wt%, cyclic life, capacity retention, and rate capabilities significantly decline due to increased CNT agglomeration.