Fig. 1.

Principle of operando neutron depth profiling of Li-metal plating and stripping. a principle and schematic setup of operando neutron depth profiling (NDP). b Operando NDP measurements of four plating and stripping cycles at 1.0 mA cm^–2 current density, showing the fractional Li density as a function of depth perpendicular to the Cu current collector. The fractional Li density is obtained by normalizing the measured Li density by the Li-metal density