Supersonically sprayed rGO−Zn₂SnO₄ composites as flexible, binder-free, scalable, and high-capacity lithium ion battery anodes

Highly flexible, binder-free, scalable, and high-capacity lithium ion battery anodes were fabricated by ball-milling SnO₂ and ZnO₂ particles to form Zn₂SnO₄/SnO₂ ternary oxide particles that were supersonically sprayed over a large area of a flexible copper foil without using any binders. The addition of rGO promoted uniform distribution of the particles and enhanced the overall performance of the composite anodes, which showed excellent long-term stability and a reversible capacity of 1316 mAh·g⁻¹ at a specific current of 100 mA g⁻¹ after 100 cycles. The supersonic deposition promoted inter-particle cohesion as well as adhesion of the coating materials onto the flexible substrate. Without added binder, the potential adverse effects of using binders on the electrical properties of the anodes were eliminated. The morphology and composition of the samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. The low-cost and scalable synthesis and deposition methods used here may offer a pathway for achieving commercially viable high-capacity anodes for various flexible electronic devices.