A nanosized SnSb alloy confined in N-doped 3D porous carbon coupled with ether-based electrolytes toward high-performance potassium-ion batteries

Abstract

Potassium-ion batteries (PIBs) have been considered as a promising new-generation energy storage device because they can be used as a replacement or complement to lithium-ion batteries. However, the large radius and the sluggish diffusion kinetics of K⁺ make it a great challenge to develop high-performance electrode materials for PIBs. Herein, a novel nanocomposite of SnSb alloy confined in N-doped three-dimensional porous carbon (3D SnSb@NC) is fabricated by using the NaCl template-assisted in situ pyrolysis strategy and investigated as an anode for PIBs based on dimethoxyethane (DME)-based and conventional ester-based (EC/DEC) electrolytes. The uniformly anchored SnSb nanoparticles could effectively alleviate dramatic volume variation during potassiation/depotassiation owing to the synergistic effect of Sn and Sb. N-doped 3D porous carbon prevents the aggregation of SnSb nanoparticles, provides abundant active sites for K⁺, facilitates sufficient infiltration of the electrolyte, and serves as a conductive network to accelerate the electron transport. Moreover, the DME-based electrolyte shows superior wettability to the 3D SnSb@NC electrode and forms a thinner SEI film, resulting in negligible surface film impedance and reduced charge transfer impedance. Consequently, the rational 3D SnSb@NC structure coupled with an optimized DME-based electrolyte makes PIBs deliver a high reversible capacity of 357.2 mA h g⁻¹ at 50 mA g⁻¹, an remarkable initial coulombic efficiency (ICE) of 90.1%, good rate capability, and excellent cycling stability with a capacity retention of 80% after 200 cycles at 0.5 A g⁻¹. This work presents an advanced concept for designing multifunctional anode materials with compatible electrolytes for high-performance PIBs.