CNT Paper as Anode for Flexible Lithium-Ion Battery
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Fig. 1. SEM (a) and High Resolution Transmission Electron Microscopy (HRTEM) (b) images of MWCNTs.
is shown in Fig. 3(b). The paper ¯bers were dehy- drated in the vacuum oven of 1465 and turned to crisp charcoal. And the MWCNTs in the CMP be- came cleaner and straighter after the heat treat- ment. It can be inferred that the crystallinity of the MWCNTs has been improved by carbonization process. And the CMP still displayed °exibility in Fig. 3(d) and su±cient strength for making an electrode in the battery. The SEM image of CMP electrode after 50 cycles is shown in Fig. 3(c), MWCNTs are tightly interlaced. The electrode keeps ¯rmly after charging and discharging. After heat treatment in vacuum oven at 1460 C for 8 h, the speci¯c surface area of the CMP is de- creasing according to the BET analysis (Fig. 4). The CMP displayed a lower surface area of 23.23 m 2 /g
indicates high degree of crystallinity. The Raman spectra [Fig. 2(b)] can be used to analyze the crys- talline qualities of MWCNTs. The intensity ratio of the G-band to the D-band ( I G = I D Þ is to evaluate the degree of crystalline perfection. 29 The value of I G / I D for the graphitized-MWCNTs is 4.16, which is much higher than that of 0.67 of the raw MWCNTs. This result is in good agreement with XRD and TEM. In the study, highly graphitized multiwalled carbon nanotubes(G-MWCNTs) were adopted. Figure 3(a) shows a web-like network structure of AMP. It indicates a good interconnection of MWCNTs in the cellulose networks. The organiza- tions of both paper ¯bers and MWCNTs are ran- dom-in-the-plane of swirled ¯brils. And the CMP
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Fig. 2. XRD patterns (a), Raman spectra (b) of raw and graphitized MWCNTs.
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