A stable full cell having high energy density realized by using a three-dimensional current collector of carbon nanotubes and partial prelithiation of silicon monoxide

Abstract

The prelithiation of SiO-based negative electrodes is essential for stable and high-energy-density Li secondary batteries. In this study, a new partial prelithiation method by two-stack electrodes was developed using lightweight and high-capacity carbon-coated silicon monoxide (SiO/C) films held in a sponge-like matrix of carbon nanotubes (CNTs). The charge-discharge cycles of a full cell with the partially prelithiated SiO/C-CNT negative electrode (p-LixSiO/C-CNT with SiO/C content of 85 mass%) and LiNi0.8Mn0.1Co0.1O2 (NCM811)-CNT positive electrode (NCM content of 97 mass%) reduced the irreversible capacity, achieving high energy densities per the total mass of the negative and positive electrodes of 542 and 420 W h kgelectrode−1 at the 1st and 300th cycle, respectively, with high areal capacities of 4.6 and 3.1 mA h cm−2 for the negative and positive electrodes. The flexible CNT sponge matrix expanded/shrunk reversibly during lithiation/delithiation and retained its structure, whereas the thin Li metal formed Li dendrites and dead Li after cycling, as demonstrated by scanning electron microscopy. The partial prelithiation method of simply stacking the pristine SiO/C-CNT film with a fully prelithiated film enables the careful control of the degree of prelithiation, contributing to full cells of various chemistries.