Hierarchical carbon-coated acanthosphere-like Li4Ti5O12 microspheres for high-power lithium-ion batteries

• Published in: Journal of power sources 2016-05, Vol.314, p.18-27
• Main Authors: Sha, Yujing, Xu, Xiaomin, Li, Li, Cai, Rui, Shao, Zongping
• Format: Article
• Language: English
• Subjects: Carbon coating; Hierarchical; Lithium titanate; Lithium-ion battery; Rate capability
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2016.02.084

In this work, carbon-coated hierarchical acanthosphere-like Li4Ti5O12 microspheres (denoted as AM-LTO) were prepared via a two-step hydrothermal process with low-cost glucose as the organic carbon source. The hierarchical porous microspheres had open structures with diameters of 4–6 μm, which consisted of a bunch of willow leaf-like nanosheets. Each nanosheet was comprised of Li4Ti5O12 nanoparticles that are 20 nm in size and coated by a thin carbon layer. When applied as the anode material for lithium-ion batteries (LIBs), the AM-LTO presented outstanding rate and cycling performance due to its unique morphologies. A high capacity of 145.6 mAh g−1 was achieved for AM-LTO at a rate of 40C (1C = 175 mAh g−1). In contrast, the sample synthesized without glucose as carbon source (denoted as S-LTO) experienced an obvious structural collapse during the hydrothermal reaction and presented a specific capacity of only 67 mAh g−1 at 1C, which further decreased to 14 mAh g−1 at 40C. Further morphological growth of the acanthosphere-like Li4Ti5O12 microspheres and their excellent performance as an anode in LIBs were also discussed in this work. Carbon-coated hierarchical acanthosphere-like Li4Ti5O12 (denoted as AM-LTO) microspheres were prepared via a facile two-step hydrothermal process with low-cost glucose as the organic carbon source. AM-LTO delivered an outstanding electrochemical performance including high capacities, good rate capabilities and cycling stability as anode materials for lithium ion batteries. A specific discharge capacity of 145.6 mAh g−1 at a high discharge rate of 40C (1C = 175 mA g−1) was obtained. Control experiments without the addition of glucose demonstrated multiple roles of glucose in the formation of the unique acanthosphere-like Li4Ti5O12 microspheres, which ensured the excellent power performances of electrode. [Display omitted] •Synthesis of carbon-coated hierarchical acanthosphere-like Li4Ti5O12 (AM-LTO).•Carbon played multiple roles during the synthesis.•The AM-LTO showed a highly open structure, ensuring relatively high lithium ion ionic diffusion.•Excellent rate and cycling performances are achieved with a capacity of 145.6 mAh g−1 at a rate of 40C.