The synergistic effect of Cu2O and boric acid forming solid electrolyte interphase layer to restrain the dendritic growth

Lithium dendrite growth has long been regarded as the main obstacle for the practical usage of lithium metal battery . In this paper, we heat-treat the copper collector at a low temperature to prepare a Cu x O (x = 1–2)/Cu composite electrode. The samples heat-treated at 250 °C are mainly composed of Cu 2 O confirmed by X-ray photoelectron spectroscopy (XPS) analysis, which has the best wettability with propylene carbonate (PC)-based electrolyte. The as-prepared Li–Cu cell (composite electrode) can run more than 150 cycles. However, boric acid additive can prolong the cycle number of Li–Cu cell to more than 300 cycles at a current density of 0.5 mA cm −2 with a Coulombic efficiency larger than 85%. Scanning electron microscopy (SEM) image shows that the Cu 2 O/Cu composite electrode with boric acid additive in the electrolyte can inhibit the formation of lithium dendrite on the surface of the electrode, and a uniform and dense nano-columnar lithium layer can be obtained even at 5 mA cm −2 . The synergistic effect is attributed to the improved interfacial properties for Cu 2 O/Cu composite collectors when boric acid (BA) is used as additives.