Preparation of Carbon Nanotube Coated Li4Ti5O12 Nanosheets

Oct 15, 2018 - Hierarchical ultrathin lithium titanate (LTO) nanosheets were in situ synthesized inside the carbon nanotubes via a ...
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Preparation of Carbon Nanotube Coated Li4Ti5O12 Nanosheets Heterostructure as Ultra-Stable Anodes for Lithium-Ion Batteries Wenling Jiao, Chen Chen, Chongyun Liang, and Renchao Che ACS Appl. Energy Mater., Just Accepted Manuscript • Publication Date (Web): 15 Oct 2018 Downloaded from http://pubs.acs.org on October 15, 2018

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ACS Applied Energy Materials

Preparation of Carbon Nanotube Coated Li4Ti5O12 Nanosheets Heterostructure as Ultra-Stable Anodes for Lithium-Ion Batteries Wenling Jiao1, Chen Chen2, Chongyun Liang3 and Renchao Che 1* 1

Laboratory of Advanced Materials, Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University, Shanghai 200438, China

2

Department of Macromolecular Science, Fudan University, Shanghai 200438, China 3

Department of Chemistry, Fudan University, Shanghai 200438, China

ABSTRACT Hierarchical ultra-thin lithium titanate (LTO) nanosheets were in-situ synthesized onside the carbon nanotubes via a precursor-morphology-controlled conversion strategy, which achieves good rate capacity and cycling stability, since it possesses more lithium-insertion channels and good electronic conductivity simultaneously. The as-prepared CNT@LTO materials exhibit a high specific capacity of 172.5 mA h g-1 at 10 C and long cycling stability with only 0.014% capacity loss per cycle. Ex-situ electron energy loss spectroscopy (EELS) analysis of CNT@LTO materials at three different stages verifies that during charge-discharge process only a fraction of the Ti4+ are reduced to Ti3+ and the specific electrode reaction of spinel LTO occurs from spinel phase to rock-salt phase. Compared with pure LTO, CNT@LTO exhibit more stable cycle performance and better electronic conductivity, which demonstrates that the CNTs not only provide good conductivity but also maintain structural stability. Keywords: hierarchical Li4Ti5O12 nanosheets, single CNT coated, EELS, ultra-stable, anode material, lithium ionic battery

Corresponding author. Tel.: (+86)-21-51630213, Fax: (+86)-21-51630210, *E-mail: [email protected]

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1.

INTRODUCTION Great attention has been paid in the development of electrode materials design of lithium

ionic batteries (LIBs) due to LIBs have showed great potential for large-scale applications, such as electric vehicles, stationary energy backup systems and fast charging electronics.1-2 Hence, the anode materials with high energy density and high stability have been extensively investigated. Particularly, lithium titanate (Li4Ti5O12, LTO) is an emerging electrode material because of its compatibility with electrolytes, high operating voltage (1.55 V vs. Li+/Li) and fast lithium ion mobility.3-4 Additionally, there is none volume change occurs in LTO during the lithium extraction and insertion processes (“zero strain”), which demonstrates the minimum chance of the formation of dendritic lithium and SEI. These attractive advantages of LTO materials may promote the potential of good safety, high cycling stability and high rate capability of LIBs.5 However, the practical applications of LTO are restricted by the low electronic conductivity (