Electrodeposition of copper–tin nanowires on Ti foils for rechargeable lithium micro-batteries with high energy density

Abstract We report the optimized fabrication of copper–tin material in the form of nanowires perpendicular to the current collector with diameters ranging between 80 and 100 nm and 2 μm length via an electrochemical deposition process. This approach aims to validate fabrication of thin films containing nanoparticles by taking the advantage of using an additive-free route for potential application in 3D-Li micro-batteries. We have analyzed the importance of controlling pure phases to obtain a high first cycle reversibility in a series of Cu 6 Sn 5 -based films. The capacity is retained during a large number of cycles. In particular, a stable gravimetric capacity of 295 mA h g − 1 or 70 μA h cm − 2 areal capacity over 100 cycles is obtained for η′-Cu 6 Sn 5 under 50 μA cm − 2 rate. This behavior is mostly ascribable to the electrode nano-architecture and phase composition even though Cu content in the film decreased specific capacity. On decreasing the nanowire size, the surface energy increases, thus minimizing particle agglomeration and volume variations in the Li–Sn alloy.