スズ―鉄合金めっき負極を用いた次世代リチウム二次電池の作製とその充放電特性

Abstract

Charge-discharge behaviors for tin-12% iron alloy films on electrolytic copper foils prepared by electroplating, which were low cost and made of environmentally friendly alloy, were investigated for X-ray a diffraction measurement, cyclic voltammetry and charge-discharge tests. Tin-12% iron alloy plating anodes showed a discharge capacity of 374 mAh/g after 50 cycles with metallic lithium as counter electrodes. From the results of cyclic voltammograms for tin-12% iron alloy plating anodes, the current value for lithium deposition increased around 0.26 V in the first cycle and increased around 0.68 V in the second cycle. The current value for lithium deposition in tin plating anodes increased around 0.66 V in the first cycle. These results suggested that iron was separated from tin-iron alloy plating film in the first charge and electric conductivity of tin-lithium intermetallic compounds formed bycharge-discharge reactions was improved by the dispersion of iron particles between these compounds. At a discharge rate of 5C(50 A/m2) tin-12% iron alloy plating anodes showed a discharge capacity of 285 mAh/g after 50 cycles and was applicable for high discharge rate. A coin-type cell(CR 2032) with a tin-12% iron alloy plating anode and a LiCoO2 cathode showed a discharge capacity of 273 mAh/g and coulombic efficiency of 90.4% after 95 cycles in charge-discharge tests at a constant charge capacity of 302 mAh/g. Therefore, tin-12% iron alloy plating anodes can be expected to substitute for carbon as high capacity anodes for advanced lithium secondary batteries.