• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.5
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• pp.189-193
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• 2003

Initial irreversible capacity (IIC) can be defined by means of the initial intercalation Ah efficiency (IIE) and the initial irreversible specific capacity at the surface (IICs) with the linear-fit range of the intercalation so as to precisely express the irreversibility of an electrode-electrolyte system. Their relationship was IIC = Qc - Q$_{D}$ = (IIE$^{-1}$ - 1) Q$_{D}$ + IICs in the linear-fit range of IIE. Here, Qc and Qd signify charge and discharge capacity, respectively, based on a complete lithium ion battery cell. Charge indicates lithium insertion to carbon anode. Two terms of IIE and IICs depended on the types of active materials and compositions of the electrode and electrolyte but did not change with charging state. In an ideal electrode-electrolyte system, IIE and IICs would be 100%, 0 mAh/g for the electrode and mAh for the cell, respectively. These properties can be easily obtained by the Gradual Increasing of State of Charge (GISOC).OC).

• Journal of the Korean Electrochemical Society
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• v.5 no.4
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• pp.173-177
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• 2002

Electrochemical characteristics of a graphite/lithium and a $LiCoO_2/lithium$ half cell and a $graphite/LiCoO_2$ full cell were analyzed using a GCSOC (gradual control test of the state of charge) technique. The IIE (initial intercalation coulombic efficiency), which represents lithium intercalation property of the electrode material, and the $lIC_s$ (initial irreversible capacity by the surface), which represents irreversible reaction between the electrode surface and the electrolyte were obtained from the GCSOC analysis. Linear-fittable capacity ranges of IIE of graphite and $LiCoO_2$ electrodes were 370 and 150 mAh/g, respectively, based on material weight. The value of lIE for graphite and $LiCoO_2$ electrodes were $93-94\%$ and $94-95\%$, respectively. The value of IICs for graphite and $LiCoO_2$ electrodes were 15-17 mAh/g and 0.3-1.7 mAh/g, respectively. The value of IIE for $graphite/LiCoO_2$ full cell, used GX25 and DJG311 as a graphite, was $89-90\%$ that lower than that for the half cells. Parameters of IIE and IICs can also be used to represent not only half cell but also full cell.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.636-643
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• 2006

Si-C materials were synthesized by the heating the mixture of silicon and polyvinylidene fluoride (PVDF). The electrochemical properties of the Si-C materials as the high capacitive anode materials of lithium secondary batteries were evaluated by the galvanostatic charge-discharge test through 2032 type $Si-C{\mid}Li$ coin cells. Charge-discharge tests were performed at C/10 hour rate(C = 372 mAh/g). Initial discharge and charge capacities of $Si-C{\mid}Li$ cell using a Si-C material derived from PVDF(20wt.%) were found to be 1,830 and 526 mAh/g respectively. The initial discharge-charge characteristics of the developed Si-C electrode were analyzed by the electrochemical galvanostatic test adopting the capacity limited charge cut-off condition(GISOC). The range of reversible specific capacity IIE(intercalation efficiency at initial discharge-charge) and IICs(surface irreversible specific capacity) were 216 mAh/g, 68 % and 31 mAh/g, respectively.