Constructing Novel Si@SnO2 Core–Shell Heterostructures by Facile Self-Assembly of SnO2 Nanowires on Silicon Hollow Nanospheres for Large, Reversible Lithium Storage

• Published in: ACS applied materials & interfaces 2016-03, Vol.8 (11), p.7092-7100
• Main Authors: Zhou, Zheng-Wei, Liu, Yi-Tao, Xie, Xu-Ming, Ye, Xiong-Ying
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.6b00107

Developing an industrially viable silicon anode, featured by the highest theoretical capacity (4200 mA h g–1) among common electrode materials, is still a huge challenge because of its large volume expansion during repeated lithiation–delithiation as well as low intrinsic conductivity. Here, we expect to address these inherent deficiencies simultaneously with an interesting hybridization design. A facile self-assembly approach is proposed to decorate silicon hollow nanospheres with SnO2 nanowires. The two building blocks, hand in hand, play a wonderful duet by bridging their appealing functionalities in a complementary way: (1) The silicon hollow nanospheres, in addition to the major role as a superior capacity contributor, also act as a host material (core) to partially accommodate the volume expansion, thus alleviating the capacity fading by providing abundant hollow interiors, void spaces, and surface areas. (2) The SnO2 nanowires serve as a conductive coating (shell) to enable efficient electron transport due to a relatively high conductivity, thereby improving the cyclability of silicon. Compared to other conductive dopants, the SnO2 nanowires with a high theoretical capacity (790 mA h g–1) can contribute outstanding electrochemical reaction kinetics, further adding value to the ultimate electrochemical performances. The resulting novel Si@SnO2 core–shell heterostructures exhibit remarkable synergy in large, reversible lithium storage, delivering a reversible capacity as high as 1869 mA h g–1@500 mA g–1 after 100 charging–discharging cycles.