Structural engineering of sulfur-doped carbon encapsulated bismuth sulfide core-shell structure for enhanced potassium storage performance

Owing to the high theoretical capacity, metal sulfides have emerged as promising anode materials for potassium-ion batteries (PIBs). However, sluggish kinetics, drastic volume expansion, and polysulfide dissolution during charge/discharge result in unsatisfactory electrochemical performance. Herein, we design a core-shell structure consisting of an active bismuth sulfide core and a highly conductive sulfur-doped carbon shell (Bi2S3@SC) as a novel anode material for PIBs. Benefiting from its unique core-shell structure, this Bi2S3@SC is endowed with outstanding potassium storage performance with high specific capacity (626 mAh.g(-1) under 50 mA.g(-1)) and excellent rate capability (268.9 mAh.g(-1) at 1 A.g(-1)). More importantly, a Bi2S3@SC//KFe[Fe(CN)(6)] full cell is successfully fabricated, which achieves a high reversible capacity of 257 mAh.g(-1) at 50 mA.g(-1) over 50 cycles, holding great potentials in practical applications. Density functional theory (DFT) calculations reveal that potassium ions have a low diffusion barrier of 0.54 eV in Bi2S3 due to the weak van der Waals interactions between layers. This work heralds a promising strategy in the structural design of high-performance anode materials for PIBs.

Automated summary

A core-shell structure Bi2S3@SC was designed as a novel anode material for potassium-ion batteries, showing excellent electrochemical performance with high specific capacity and rate capability. Density functional theory calculations revealed low diffusion barrier of potassium ions in Bi2S3, providing theoretical basis for the design of high-performance anode materials.