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The inevitable problem of dendrites growth has hampered the further development of K metal anodes. Constructing a three-dimensional anode framework and potassiophilic nanocoating is an effective way to enlarge the specific surface area, reduce the local current density, and inhibit the formation of K dendrites. However, the effects of the electrochemically active surface area (ECSA) of the framework on deposition behavior have not been clarified. Hence, SnS 2 nanosheets with different sizes are loaded on the surface of carbon paper (SnS 2 @CP) to improve the potassiophilicity and realize dendrite-free K-metal anodes. Experiments reveal that the size of SnS 2 nanosheets would determine the ECSA of the framework, while the ECSA reveals the relative sizes of specific surface areas of frameworks. Excessive or limited specific surface areas will cause morphological collapse or weak potassiophilicity during potassiation, respectively, thus leading to high nucleation overpotential. The moderate specific surface area and abundant and stable potassiophilic sites prompt the SnS 2 @CP framework to achieve uniform electrodeposition of K. A low nucleation overpotential of 11.2 mV and a cycle life of more than 800 h are exhibited at a current density of 0.25 mA cm −2 , indicating the directional strategy for stable and safe K metal anodes.

Uncontrollable formation of Li dendrites and volume expansion have always been serious obstacles to the practical application of Li metal anodes. Three-dimensional (3D) frameworks are proven to accommodate Li to suppress volume expansion, but the lithiophobic surface tends to cause uncontrollable formation of Li dendrites. Here, uniform SnS 2 nanosheets are coated on the carbon paper (SnS 2 @CP) skeleton and then transformed into a mixed layer of Li 2 S/Li−Sn after lithiation. Under the joint action of the lithiophilic Li−Sn alloy and lowdiffusion energy barrier Li 2 S, the dual effects of strong adsorption and rapid diffusion of Li are realized. As a result, Li deposits homogeneously within the whole framework; as the plating amount increases, dendritefree spherical Li is demonstrated, and the thickness of the electrode stays almost unchanged even at a high areal capacity of 10 mA h cm −2 . The SnS 2 @CP electrodes present an ultralow nucleation overpotential (ca. 4 mV), high Coulombic efficiency (above 96.6% for more than 450 cycles), and stable cycle life (>1500 h), indicating that the 3D framework with the Li 2 S/Li−Sn alloy mixed coating has excellent lithiophilicity and fast Li transport kinetics, thus effectively inhibiting the formation of Li dendrites. All the findings give new insights into the design strategy for stable and safe Li metal anodes.