Mercaptopropionic Acid-Capped Wurtzite Cu9Sn2Se9 Nanocrystals as High-Performance Anode Materials for Lithium-Ion Batteries.

In this research, we provide a simple but sound solution to address the low performance of lithium-ion batteries through preparation of wurtzite Cu9Sn2Se9 nanoparticles with uniform size distribution and morphology via a hot injection colloidal approach as a promising anode material. The Cu9Sn2Se9 nanoparticles anode exhibits superior rate performance and high reversible capacity of 979.8 mAh g-1 in the 100th cycle at a current density of 100 mA g-1, which is approximate 2 times of reported Cu-Sn-S framework (563 mA g-1), 1.5 times of reported pristine Cu2SnS3 (621 mA g-1) and comparable or higher than a number of reported Sn-based nanocomposites based anodes for lithium-ion batteries at the same cycle. The study demonstrate such outstanding properties are attributed to the high structural flexibility of the metal selenide and increased electronic connectivity by colloidal quantum dot ligand exchange procedure associated with mercaptopropionic acid (MPA). In addition, unlike most metal sulfides or selenides, it possesses a stepwise intercalation mechanism during the lithiation/delithiation cycles which is beneficial to buffer against volume variation of the alloy electrode materials. Such findings provide a new and feasible insight into guide the design and manufacturing of high performance lithium-ion batteries for a broad variety of engineering applications.