A copper tetrathiovanadate anode for ultra-stable potassium-ion storage

Given the abundant natural reserves of potassium and its similar properties to lithium, potassium-ion batteries (KIBs) are expected to be an emerging energy storage system to replace lithium-ion batteries (LIBs). Here, to overcome the sluggish diffusion kinetics and structure collapse of the anode in current KIBs, copper tetrathiovanadate (Cu3VS4) nanoparticles uniformly loaded in carbon nanofibers (CVS/CNF) are designed as a new anode for KIBs through electrospinning and subsequent carbonization/sulfidation treatment. Benefiting from the highly conductive Cu species and CNF network, an outstanding charge transfer kinetics is achieved in CVS/CNF composites. Meanwhile, the nanosized CVS particles and robust CNF networks are believed to be beneficial for enhanced structural stability during potassium insertion, and thus endow the composite anode with an excellent long-term capability. The CVS/CNF composite anode displays a high capacity (486 mA h g-1 at 0.1 A g-1), great rate feature (162 mA h g-1 at 6 A g-1) and outstanding cycling performance (193 mA h g-1 after 2000 cycles at 1 A g-1), which are superior to those of most of the reported transition metal sulfide anodes.