Date Published: January 03, 2018
Publisher: John Wiley and Sons Inc.
Author(s): Zhujun Yao, Xinhui Xia, Cheng‐ao Zhou, Yu Zhong, Yadong Wang, Shengjue Deng, Weiqi Wang, Xiuli Wang, Jiangping Tu.
Exploring advanced high‐rate anodes is of great importance for the development of next‐generation high‐power lithium‐ion batteries (LIBs). Here, novel carbon nanotubes (CNTs)/Li4Ti5O12 (LTO) core/shell arrays on carbon cloth (CC) as integrated high‐quality anode are constructed via a facile combined chemical vapor deposition–atomic layer deposition (ALD) method. ALD‐synthesized LTO is strongly anchored on the CNTs’ skeleton forming core/shell structures with diameters of 70–80 nm the combined advantages including highly conductive network, large surface area, and strong adhesion are obtained in the CC‐LTO@CNTs core/shell arrays. The electrochemical performance of the CC‐CNTs/LTO electrode is completely studied as the anode of LIBs and it shows noticeable high‐rate capability (a capacity of 169 mA h g−1 at 1 C and 112 mA h g−1 at 20 C), as well as a stable cycle life with a capacity retention of 86% after 5000 cycles at 10 C, which is much better than the CC‐LTO counterpart. Meanwhile, excellent cycling stability is also demonstrated for the full cell with LiFePO4 cathode and CC‐CNTs/LTO anode (87% capacity retention after 1500 cycles at 10 C). These positive features suggest their promising application in high‐power energy storage areas.
Materials Synthesis: Synthesis of CC‐CNTs/LTO Electrode: First, CNTs arrays on CC were synthesized by a facile CVD with ethanol as the carbon precursor. The CC substrate was immersed in Ni(NO3)2 ethanol solution for 4 h and dried under 60 °C. Then the CC with catalyst was put into a tube furnace and treated at 600 °C under a mixed‐gas atmosphere of 140 sccm Ar + 10 sccm H2 for 30 min. Then Ar + H2 gas saturated with ethanol was introduced in the furnace for 90 min. Then, the sample was immersed into a solution with 1 m HCl and 1 m FeCl3 at 80 °C for 12 h to remove the Ni catalyst to form CC‐CNTs arrays. Second, TiO2 was fabricated on CNTs by an ALD (Beneq TFS 200) method using TiCl4 and H2O as the Ti and O precursors, respectively. Finally, the CC‐CNTs/TiO2 electrode was converted into CC‐CNTs/LTO by a simple chemical lithiation method. The as‐prepared CC‐CNTs/TiO2 electrode was placed in a 100 mL Teflon‐lined autoclave filled with 70 mL 3 m LiOH aqueous solution for 1 h at 80 °C and annealed under Ar atmosphere at 500 °C for 2 h to form CC‐CNTs/LTO core/shell arrays. The dependence of capacity and LTO mass was shown in Figure S6 (Supporting Information). The capacity would decrease as the LTO mass increases. Here, 2 mg cm−2 was selected as the representative.
The authors declare no conflict of interest.