Polyaniline spaced MoS2 nanosheets with increased interlayer distances for constructing high-rate dual-ion batteries

Abstract

Dual-ion batteries (DIBs) have attracted great attention due to their affordable prices, environmental friendliness, and high operating voltage. However, the conventional graphite anode in DIBs has drawbacks such as unsatisfactory capacity and worrying safety. MoS2 is considered to be a competitive anode material that exhibits large capacity due to its unique layered structure for cation insertion/extraction. Nevertheless, the sluggish reaction kinetics of MoS2 does not match the cathode side, which makes the constructed full DIBs show poor rate ability. Here, a flower-like MoS2/ polyaniline composite electrode (MoS2-PANI) where PANI was grown in situ between layers of MoS2 nanosheets was designed. In this design, the inserted PANI can broaden the layer distance of MoS2 to facilitate cation diffusion and prevent the restacking of nanosheets. Furthermore, PANI is also expected to increase the conductivity and relieve the volume changes during repeated charge/discharge cycles. Benefiting from that, the MoS2-PANI electrode delivered a reversible capacity of 561.91 mA h g–1 at 5 A g–1 in half-cell test. Moreover, when coupled with a mildly expanded graphite (MEG) cathode, the obtained MEG//MoS2-PANI DIB shows excellent rate ability with a reversible discharge capacity of 86.62 mA h g–1 and a desirable energy density of 308.83 W h kg–1 at 20 C. These results provide some inspiration for the design of high-rate DIBs.