Revealing the complex lithiation pathways and kinetics of core-shell NiO@CuO electrode

Nanostructured composite electrodes with multiple active phases offer extraordinary performance that can be harnessed in future batteries. However, it is difficult to disclose the complicated reaction pathways. In this work, NiO@CuO core-shell nanocomposites are prepared and used as anodes for lithium-ion batteries, with superior rate and stability performance compared with single-phase CuO and NiO. Using a combination of in situ and ex situ electron microscopy, a two-stage lithiation reaction pathway on NiO@CuO is identified, with CuO reduced to Cu₂O first and followed by the simultaneous reduction of both Cu₂O and NiO to metals, resolving the existing inconsistency in literature. Chemomechanical simulation further discloses the key role of the core-shell structure in high cycling stability of NiO@CuO, which decreases the probability of cracking during the discharge-charge process. This work provides new insights to explore lithiation mechanisms and kinetics in novel electrodes, which contribute to further development of various electrode materials.