Wet chemical route to the synthesis of kesterite Cu₂ZnSnS ₄ nanocrystals and their applications in lithium ion batteries

Sn-based quaternary material, Cu₂ZnSnS₄ (CZTS), was successfully synthesized using an inexpensive and quick wet chemical route. The obtained CZTS nanocrystals were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and selected area electron diffraction (SAED) techniques. XRD and SAED results revealed that kesterite CZTS was formed. The formed CZTS nanocrystals were slightly irregularly faceted particles with diameters between 5 nm and 25 nm. CZTS was studied as an anode material in rechargeable lithium ion battery for the first time. The Cu ₂ZnSnS₄ annealed at 500 °C showed a capacity of about 540 mA h g^-1 at the initial stage. The first cycle of the CZTS electrode exhibited enormously irreversible capacity. The result indicated that the formation of metallic Sn from the Cu₂ZnSnS₄ powder was similar to the case in SnO₂ or SnS₂ electrodes. Cu ₂ZnSnS₄ was demonstrated to be one of the possible candidates of the anode materials for future lithium ion battery.