Fig. 2. Long-term cycling performance of the symmetric Li–Li cells with BTT and blank electrolyte.

a Plating and stripping curves for the two types of symmetric cells with a current density of 0.5 mA cm⁻² and a capacity density of 0.5 mAh cm⁻². b Both types of cells at a current density of 1 mA cm⁻² and a capacity density of 1 mAh cm⁻². c Both types of cells at various currents and the cells cycled under 1 h charge and discharge conditions. d, e AFM images for the lithium foil with BTT electrolyte after 100 cycles with a current density of 0.5 mA cm⁻² and a capacity density of 0.5 mAh cm⁻². f, g AFM images for the control cell. h Schematic diagram of the flexible organic-inorganic SEI in BTT electrolyte and dendrite lithium in blank electrolyte.