Atomic-Layer-Deposited Amorphous MoS₂ for Durable and Flexible Li–O₂ Batteries

Li–O₂ batteries (LOB) potentially have the highest specific capacity among all types of metal-ion batteries but suffer severely from cycle instability and low energy efficiency. In this work, an integrated cathode is fabricated that contains an amorphous MoS₂ thin layer deposited on a 3D conductive carbon scaffold to improve the energy efficiency to ≈83% and cycle life up to 190 cycles. An advanced pressure-tuned stop-flow atomic layer deposition (ALD) method is employed to deposit a ≈5 nm thick amorphous MoS₂ layer on carbon nanotube forest-covered graphite foam. It is established that this integrated 3D cathode exhibits high catalytic activity for both oxygen reduction reaction and oxygen evolution reaction. The benefit of the ALD MoS₂ in lowering the energy barrier is also supported by first-principles calculations. Finally, quasi-solid state flexible LOBs are also assembled that can be stably discharged up to 6 d. This new and rational design of cathode may provide a new direction for achieving high-performance flexible Li–O₂ batteries.