Fig. 4: Experimental study and FEM simulations on the interfacial stability of LPE@Ni-DMF with Li metal.

a Cycling stability of the Li | |Li symmetric cells at a current density of 0.1 mA cm⁻² with capacity of 0.1 mAh cm⁻² per half cycle. The insets are the magnified images at the selected time period. b CCD of LPE and LPE@Ni-DMF. The plating/stripping time for half cycle is set to 1 h. c Tafel curves with calculated ECD of the Li | |Li symmetric cells with a scanning rate of 0.1 mV s⁻¹. Cryo-TEM and corresponding FFT images for the component analyses in LPE-SEI (d) and LPE@Ni-DMF-SEI (e). f F/C elemental ratio in LPE-SEI and LPE@Ni-DMF-SEI. Values are means, and error bars were calculated by taking the standard errors from one sample for three measurements. g FEM simulation results of the evolution of SEI thickness in a Li | |Li symmetric cell model. The color from blue to red represents the increase of SEI thickness. h The Li⁺ concentration distribution at the interface between SEIs and Li anodes and the local current density distribution on Li surface (at the state of 1 h charging). The Li anode morphology evolution related to Li⁺ concentration distribution (at the state of 1 h charging) on Li surface under the influence of (i) LPE-SEI and (j) LPE@Ni-DMF-SEI. The stacked curves from bottom to top represent the Li deposition thickness of different locations on the selected line, and the line colors change with the charging time.