Biomass-derived two-dimensional N,O-doped carbon with embedded binary-metal nanoparticles enables dendrite-free potassium-metal anodes

Abstract

Potassium metal batteries (PMBs) are expected to become the most promising new generation of new type large-scale energy storage equipment owing to their abundant resources, low cost, and low operating potential. However, the direct use of metallic potassium (K), especially the “hostless” K metal, leads to easy growth of dendrites that pierce the separator, resulting in a short circuit of the battery. In this work, a simple and effective strategy to construct dendrite-free PMBs via plating metallic K into binary-metal (NiCo, NiFe, CoFe) nanoparticle-embedded two-dimensional (2D) N,O co-doped carbon (K–NiCo@NOGC, K–NiFe@NOGC, K–CoFe@NOGC) was proposed. The factors affecting the electrochemical performance of potassium metal cells were discussed from the aspects of experiment and theoretical calculation. Our fundamental studies reveal that potassium dendrite growth can be effectively inhibited on the substrate containing nitrogen-oxygen rich functional groups, as confirmed by low nucleation overpotential, high coulombic efficiency and enhanced adsorption energy. Among the three kinds of synthesized materials, NiCo@NOGC can serve as an ideal host for dendrite-free potassium deposition and exhibits outstanding stable cycling performance with high coulombic efficiency (CE) at a current density of 0.5 mA cm⁻² (CE = 99.4% after 450 cycles). Moreover, the practicality and functionality of this anode are demonstrated by assembling K–NiCo@NOGC‖PB full batteries with a long cycle life of 500 cycles and a high-capacity retention of 80%.