On the performance of a hierarchically porous Ag2S-CuxS electrode in Li-ion batteries

A new binder- and carbon-free electrode for lithium-ion batteries was prepared using a hierarchically porous Ag-based current collector. The latter was produced by applying the method of selective dissolution of the less noble metals from the Cu60Ag30Al10 master alloy tape. The current collector was reaction-coated with an electrochemically active Ag2S-CuxS coating. The metallic structure provided a mechanically stable conductive scaffold on the walls of which the Ag2S-CuxS skin material was directly deposited. The ordered porosity - hierarchical and directional - provided easy penetration of the liquid electrolyte as well as short Li+ ion diffusion paths. The as-prepared electrodes were tested in a half-cell configuration vs. Li/Li+ at various current rates to study the cycling and rate performances of the electrode. The first cycling capacity of similar to 1250 mA h g(-1) was measured at 0.4 A g(-1) current rate. After a rapid decrease, a stable reversible capacity of similar to 230 mA h g(-1) was established at a current rate of 0.4 A g(-1) (calculated vs. the weight of the incorporated sulphur). Excellent charge/discharge cycling and rate properties were observed for over 1000 cycles at higher rates of 1.0 and 2.0 A g(-1), in the potential window of 0.15-2.8 V vs. Li/Li+. The observed cycling stability was ascribed to the mechanism of a displacement reaction with Li ions. Additional capacity is also available from alloying-dealloying with Ag (and Cu to some extent) and S redox reactions. These results open up a new opportunity for using a Cu-Ag alloy as the precursor for making electrodes for thin Li-ion and Li-S batteries with high cycling stability at relatively high current rates.

Automated summary

A binder- and carbon-free electrode for lithium-ion batteries was prepared using a hierarchically porous Ag-based current collector. The electrode exhibited excellent cycling and rate properties, maintaining high cycling stability even at relatively high current rates.