Constructing radially oriented macroporous spheres with central cavities as ultrastable lithium-ion battery anodes

Huge volume expansion and structural degradation of transition-metal oxide electrode materials upon cycling often lead to severe capacity fading in lithium ion batteries (LIBs). To overcome these technical barriers, here we report the design and synthesis of a new type of high-performance anode material composed of CuO or hybrid MxOy-CuO (M = Zn, Ni, Co, Mn or both of them), which has three unique structural features: (i) 1D porous nanorods with multi-phase intergrowth feature as building blocks, (ii) central cavity originated from the radially aligned nanorods, and (iii) constructed microspheres with low outer surface area. When applied for LIBs anode, 10ZnO-CuO exhibited high capacity retention with 612 mA h g(-1) even after 600 cycles. This enhanced lithium storage is closely related to the unique structural features and the generated multi-phase synergistic effect that could facilitate fast electro/ ion transport and buffer volume expansion. For example, the in-situ TEM observation confirmed that the central cavity and porous geometry had almost zero volume stress, thus being able to effectively accommodate the volume change; the presence of the Job-sharing mechanism among multi-phases contributed to the enhanced capacities, etc. This work demonstrates that this strategy is versatile and facile for constructing the 3-order hierarchy structures for various metal oxide systems, and the formed structures have ample applications in various areas.