Polyaniline intercalated lithiation‐assisted exfoliation of MoS2 cathode enables ultra-high rate and durable rechargeable magnesium ion batteries

The commercialization of rechargeable magnesium ion batteries (MIBs) faces a critical challenge in exploiting high-performance cathodes, owing to the sluggish kinetics resulting from the robust Coulombic interaction between doubly charged Mg 2+ ions and the intercalation host. Herein, a polyaniline (PANI) intercalated lithiation‐assisted exfoliation of MoS 2 (Li x -MoS 2 @PANI) cathode is developed through an initial chemical lithiation and delamination of commercial MoS 2 with n-butyllithium, followed by in-situ growth of PANI into the MoS 2 interlayers. Notably, the obtained Li x -MoS 2 @PANI displays a graphene-like nanosheet morphology with the interlayer spacing expanded to around 0.74–1.09 nm. The down-sizing of the exfoliated MoS 2 and expanded interlayer spacing could efficiently shorten ion diffusion distance and improve Mg 2+ diffusion kinetics by weakening the strong Mg 2+ -host interactions. Moreover, the intercalated PANI is expected to enhance the conductivity and accommodate the volume changes upon prolonged cycling. The synergistic effects of the above boost the electrochemical performance of Li x -MoS 2 @PANI cathode, achieving high specific capacity, excellent rate capability even at an ultra-high rate of 15.0C and unprecedented long-term cycling stability with a reversible capacity of 140.5 mAh g −1 at 15.0C up to 2800 cycles. This work offers an efficient and universal modification strategy to rational design high-performance intercalation-type cathodes for MIBs.