Construction of MnO2 Artificial Leaf with Atomic Thickness as Highly Stable Battery Anodes.

The leaf-like structure is a classic and robust structure and its unique vein support can reduce structural instability. However, biomimetic leaf structures on the atomic scale are rarely reported due to the difficulty in achieving a stable vein-like support in a mesophyll-like substrate. A breathable 2D MnO2 artificial leaf is first reported with atomic thickness by using a simple and mild one-step wet chemical method. This homogeneous ultrathin leaf-like structure comprises of vein-like crystalline skeleton as support and amorphous microporous mesophyll-like nanosheet as substrate. When used as an anode material for lithium ion batteries, it first solves the irreversible capacity loss and poor cycling issue of pure MnO2 , which delivers high capacity of 1210 mAh g-1 at 0.1 A g-1 and extremely stable cycle life over 2500 cycles at 1.0 A g-1 . It exhibits the most outstanding cycle life of pure MnO2 and even comparable to the most MnO2 -based composite electrode materials. This biomimetic design provides important guidelines for precise control of 2D artificial systems and gives a new idea for solving poor electrochemical stability of pure metal oxide electrode materials.