Effect of orientation on the reversible discharge capacity of electrodeposited Cu2O coatings as lithium-ion battery anodes

Electrochemical impedance studies of capacity fading of electrodeposited ZnO conversion anodes in Li-ion battery

“…To address this issue, impedance measurements were made before cycling and after several (1, 5, 10, 20 and 25) chargedischarge cycles. These are compared with similar data obtained from Cu 2 O coatings used for comparison [5], as the latter yielded steady reversible discharge capacities over several cycles.…”

“…In this aspect, the electrocrystallization of ZnO is different from that of an oxide such as Cu 2 O, wherein differently oriented coatings expose crystal faces [24] with different surface energies. Accordingly, the UV-Vis spectra of differently oriented Cu 2 O coatings show different values for λ max [5], but the spectra of differently oriented ZnO coatings look identical ( figure 5). If the λ max value (365 nm) is seen as a measure of the band gap, then the band gap (3.4 eV) and consequently, the conductivity The spent ZnO anodes were recovered after 25 chargedischarge cycles.…”

“…Impedance spectra were recorded before cycling and after the completion of 1, 5, 10, 20 and 25 charge-discharge cycles. Similar cells were fabricated using Cu 2 O coatings as described elsewhere [5] and impedance spectra were recorded for these as well for use as control. The excitation signal was 5 mV (rms) at open-circuit voltage (3.0 V before chargedischarge cycle and 1.0 V after 25 charge-discharge cycles), and the frequency range was from 100 kHz to 10 mHz.…”

“…In contrast, an oxide such as Cu 2 O (Pn-3m, a = 4.2672 Å), which also offers cost advantages, delivers a stable capacity of 220 mAh g −1 in conversion anodes with an extended cycle life [3,4]. A recent investigation of electrodeposited Cu 2 O coatings showed that the 200-oriented coating delivered a stable reversible capacity 16% higher than that delivered by the 111-oriented coating [5]. The higher deliverable capacity of the 200 crystal face of Cu 2 O was attributed to its polar nature, whereby, it has a high surface energy and enhanced reactivity towards the incoming Li atoms.…”