Sulfur-Rich (NH4)2Mo3S13 as a Highly Reversible Anode for Sodium/Potassium-Ion Batteries.

Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have attracted much attention owing to the inexpensive Na/K metal and satisfactory performance. Currently, there are still difficulties in research anode materials that can insert/extract Na/K ions quickly and stably. Herein, the sulfur-rich (NH4)2Mo3S13 is proposed as the anode for SIBs/PIBs and is obtained by a hydrothermal method. The sulfur-rich (NH4)2Mo3S13 with a three-dimensional structure shows a high capacity and long lifespans for Na+ (at 10 A g-1 the capacity of 165.2 mAh g-1 after 1100 cycles) and K+ (120.7 mAh g-1 at 1 A g-1 retained after 500 cycles) storage. In addition, the (NH4)2Mo3S13 electrode exhibits excellent electrochemical performance at low temperatures (0 °C). The mechanism of Na+ storage in (NH4)2Mo3S13 can be innovatively revealed through the combined use of electrochemical kinetic analysis and a series of ex situ characterization tests. It is believed that the present work identifies (NH4)2Mo3S13 as a promising anode for the SIBs/PIBs and will be of broad interest in research on engineering sulfur-rich transition metal sulfide and on energy storage devices.