Electrochemical kinetics of porous, carbon-decorated LiFePO4 cathodes:: separation of wiring effects from solid state diffusion

被引:59
作者
Gaberscek, Miran [1 ]
Kuzma, Mirjana [1 ]
Jamnik, Janez [1 ]
机构
[1] Natl Inst Chem, SI-1000 Ljubljana, Slovenia
关键词
D O I
10.1039/b618822b
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We try to identify the rate-determining step of electrochemical kinetics of a LiFePO4-carbon composite electrode by varying the mass of electrode and, additionally, by varying the charge-discharge current in a wide range. It is shown that the reversible capacity is almost independent of electrode mass at currents lower than ca. 1 C (170 mAh g(-1)). At higher currents, however, the reversible capacity starts to drop significantly. The electrode resistance determined from the corresponding polarization voltage shows inverse proportionality with mass at currents smaller than 1 C. At higher currents the electrode resistance is almost independent of electrode mass. We conclude that at lower currents (below 1 C) the main transport step is related to the active particles themselves (either to incorporation reaction or solid state diffusion of Li). At higher currents the contribution of electronic and ionic transport towards the active particles becomes substantial and should be taken into account when designing high-rate insertion electrodes.
引用
收藏
页码:1815 / 1820
页数:6
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