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

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 51; no. 47; pp. 18045 - 18053
• Main Authors: Tomov, R I, Mihaylov, L, Bird, L R, Vassileva, Ev, Kumar, R V, Chhowalla, M, Spassov, T
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 06.12.2022
• Subjects: Copper; Copper base alloys; Cycles; Electrodes; Ion diffusion; Lithium sulfur batteries; Lithium-ion batteries; Master alloys; Noble metals; Rechargeable batteries; Redox reactions; Silver; Stability
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d2dt02880h

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 ∼1250 mA h g−1 was measured at 0.4 A g−1 current rate. After a rapid decrease, a stable reversible capacity of ∼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.