Improvement of the Ar/N 2 binary plasma-treated carbon passivation layer deposited on Li 4 Ti 5 O 12 electrodes for stable high-rate lithium ion batteries

• Published in: RSC advances 2015, Vol.5 (112), p.92554-92563
• Main Authors: Lan, Chun-Kai, Chang, Chun-Chi, Wu, Cheng-Yu, Chen, Bing-Hong, Duh, Jenq-Gong
• Format: Article
• Language: English
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/C5RA17522D

In this study, nanoscale carbon overlayers, with and without nitrogen doping, have been investigated as surface passivation layers to enhance the rate capability and cycling stability of Li 4 Ti 5 O 12 (LTO). As indicated by optical emission spectroscopy, Raman spectra and high resolution X-ray photoelectron spectroscopy analysis, nitrogen successfully dopes into the carbon overlayer by Ar/N 2 binary plasma irradiation, owing to the interaction between the carbon overlayer and chemically reactive plasma species such as N 2 + and N. In addition, the results of SEM and XPS depth profiles also prove that the N-doped carbon overlayer can effectively suppress the formation of a resistive solid–electrolyte-interface (SEI) film. The electrochemical test results demonstrate that the LTO coated with N-doped carbon overlayer (NC-overlayer/LTO) exhibits superior capacity (133 mA h g −1 ) and excellent stability with 91% capacity retention over 300 cycles at a high C rate (10C). The excellent electrochemical performance of NC-overlayer/LTO can be attributed to the N-doped carbon passivation layer that effectively facilitates Li + ion diffusion and reduces internal resistance.