Moderate Specific Surface Areas Help Three-Dimensional Frameworks Achieve Dendrite-Free Potassium-Metal Anodes

Abstract

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.

Highly Potassiophilic Graphdiyne Skeletons Decorated with Cu Quantum Dots Enable Dendrite‐Free Potassium‐Metal Anodes

“…[1][2][3][4] K possesses similar physical and chemical properties to Li, yet is a thousand times more abundant in the Earth's crust; K + /K couple shows a low As for the former, strenuous efforts have been made in the structural and compositional design. [30][31][32] For instance, Tang et al devised a self-supported defect-rich and N-containing MXene/carbon nanotube scaffold to confine K metal. [33] Such a scaffold is conducive to accommodating the volume change and suppressing the dendrite formation of K anode.…”

“…As for the former, strenuous efforts have been made in the structural and compositional design. [ 30–32 ] For instance, Tang et al devised a self‐supported defect‐rich and N‐containing MXene/carbon nanotube scaffold to confine K metal. [ 33 ] Such a scaffold is conducive to accommodating the volume change and suppressing the dendrite formation of K anode.…”

Dynamically Evolving Multifunctional Protective Layer for Highly Stable Potassium Metal Anodes

“…The two peaks at 32.9 and 31.1 eV are assigned to Ge 4+ and Ge 2+ , respectively, indicating that GeO 2 coated onto the surface of K metal is partially reduced to GeO. , The pre-protected K electrode was then assembled into the cell, and its evolution after different cycles was explored. As shown in Figure g, the peak of the K–Ge alloy is detected near 27.5 eV in the spectrum of pre-protected K after 1 cycle, which implies that GeO is further reduced to the K–Ge alloy in electrochemical cycling. , The spectrum of pre-protected K after 20 cycles in Figure h shows that the peak of GeO disappears and is completely reduced to the K–Ge alloy. Figure S2 of the Supporting Information presents the XRD pattern of protected K, indicating that it is composed mainly of KGe and GeO 2 , which is consistent with the XPS results.…”

Design of a potassiophilic 3D conductive scaffold potassium anode (3D-CTZ@K) with dendrite-free and high energy-power density in potassium metal batteries

“…49 SnS 2 nanosheets were also used on a carbon paper to realize a stable and dendrite-free K metal anode, yielding stable cycling endurance at a current density of 1 mA cm −2 . 50 SnO 2 -modified carbon cloth/nanofibers can induce the homogeneous and stable K deposition at current densities of 0.5–1.0 mA cm −2 . 51,52 These studies provide references for the design of potassiophilic 3D scaffolds, however the effective design on inhibition of volume variation with extraordinary cycle stability and high rate capability of the K anode is still challenging.…”