Carbotron

Figure 15. First- cycle constant-current charge/discharge curve of hard carbon ("Carbotron P"). The figure has been reproduced with kind permission of Kureha Chemical Industry Co., Ltd. [2381.

SEI 439 f carbonyl 234, 431 Carbotron P 400 carboxyl 234 carboxylate azides 541 carboxylic groups 431... 

Figure 11. (a) Photomicrograph of Kureha Carbotron P, (b) TEM of2800 C heat-treated Sugar carbon. 

The target of development of a novel hard carbon for HEV is to remove the ink bottle-type pore and to improve the stability and the efficiency. The hard carbon recently developed is called Carbotron P (J), and its particle size is almost the same as Carbotron PS (F), but its electrochemical characteristics are different from Carbotron P (F) and PS (F). 

Figure 22.1 shows the surface of Carbotron P (J) by scanning electron microscopy (SEM). X-ray powder diffraction (XRD) patterns of these carbons, measured on Rigaku RAD-C diffractometer with roter-flex and Cu-Ka radiation, are shown in Fig.22.2. The interlayer distances and the crystallite size factors (Lc) calculated from XRD(002) reflection using Schener formula" are given in Table 22.1. Figure 22.3 also shows the particle size distributions of these three carbons. The average particle sizes estimated from distributions are shown in Table 22.1.

Fig. 22.1 The scanning electron micrograph of the Carbotron P (J). Reprinted from Ref. 7, copyright (2006), with permission from Elsevier Ltd...

Fig. 22.3 Particle-size distributions of (A) closed diamond) Carbotron P (J), (B) open circle) Carbotron PS (F), and (C) open square) Carbotron P (F). (A) and (B) have almost the same distributions. The mean sizes of (A), (B), and (C) are shown in Table 22.1...

Table 22.3 shows how much water can be adsorbed in carbons when stored in 90%RH at 40°C for 70h. The adsorbed water content in Carbotron P (J) is dramatically decreased to less than half of that in Carbotron PS (F). Further experiments suggested that the adsorbed water content will be able to be decreased to less than 1% in near future. 

The true density of Carbotron P (J) is same as that of Carbotron PS (F). So, the pore volume in carbons is not changed. However, the capacity at the CV region and the adsorbed water content apparently are decreased. These phenomena imply that... 

Table 22.3 The weight% of adsorbed water in carbon (A) Carbotron P (J), and (B) Carbotron PS (F) Stored in 90%RH at 40°C after 70°h...

Fig. 22.5 Discharge capacity of Carbotron P (J) measured at various current density. The highest current density corresponds to 60 C...

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