Boosting Potassium Storage Performance of the Cu₂S Anode via Morphology Engineering and Electrolyte Chemistry

Abstract

Transition metal sulfides (TMSs) have been demonstrated as attractive anodes for potassium-ion batteries (KIBs) due to the high capacity, abundant resource, and excellent redox reversibility. Unfortunately, practical implementation of TMSs to KIBs is still hindered by the unsatisfactory cyclability and rate performance which result from the vast volume variation during charge/discharge processes. Herein, a uniform nitrogen-doped carbon coated Cu2S hollow nanocube (Cu2S@NC) is designed as an anode material for the KIB, which displays an outstanding cycle performance (317 mAh g–1 after 1200 cycles at 1 A g–1) and excellent rate capacity (257 mAh g–1 at 6 A g–1) in a half-cell. The hollow nanosized structure can both shorten the diffusion length of potassium ions/electrons and buffer the volume expansion upon cycling. Besides, the high concentration electrolyte is beneficial to form the stable solid electrolyte interphase (SEI) film, reducing the interface impedance and enhancing the cycling stability. Ex situ transmission electron microscopy (TEM) and ex situ X-ray diffraction (XRD) reveal the reaction mechanism of Cu2S@NC.

Boosting Coulombic Efficiency of Conversion‐Reaction Anodes for Potassium‐Ion Batteries via Confinement Effect

“…Their low electronic conductivities also hinder the improvement of the K ion storage properties. [16,17] Strategies such as elegant microstructure design, [ 11,18 ] hybridizing the active material with carbon based matrix, [ 13,19 ] etc., can improve K ion storage properties of the electrodes because of the shortened K ion diffusion distance, strengthened microstructure stability, and enhanced electronic conductivities. However, the coulombic efficiencies of the electrodes are always much lower than 99.0% in the initial dozens of cycles, and the reversible capacity cannot be stabilized before certain periods.…”

“…[ 8,10 ] Usually, anode materials with high‐capacity are always hold one or more K ions, such as conversion reaction materials, along with large volume swelling occurring. [ 11,12,13,14,15 ] Unfortunately, the volume swelling threatens the integration of the solid‐electrolyte‐interface (SEI) layers and the microstructure stability of the active materials, resulting in low coulombic efficiency and inferior cycling stability. Besides, the conversion reaction materials are always chalcogenides.…”

Promise and reality of practical potassium‐based energy storage systems

“…Peng et al demonstrated nitrogen-doped carbon coated Cu 2 S hollow nanocubes (Cu 2 S@NC) as the anode for significantly boosting PIBs. 69 The inner cavity relieved volume expansion during cycling and surface-coated nitrogen-doped carbon layer enhanced the electrical conductivity of the entire composite.…”

“…In addition, throughout precise design of nanostructures, the interface between electrode and electrolyte can be regulated, potentially leading to high initial Coulombic efficiency. Peng et al demonstrated nitrogen‐doped carbon coated Cu 2 S hollow nanocubes (Cu 2 S@NC) as the anode for significantly boosting PIBs 69 . The inner cavity relieved volume expansion during cycling and surface‐coated nitrogen‐doped carbon layer enhanced the electrical conductivity of the entire composite.…”

Boosting Potassium Storage by Integration Advantageous of Defect Engineering and Spatial Confinement: A Case Study of Sb2Se3

“…The larger radius of K + in KIB electrodes lead to sluggish electrochemical kinetics, cause higher diffusion barriers and huge volume change, resulting in poor rate performance and cycle life. [ 3 ] The biggest challenge of KIBs is development of suitable electrode materials that can accommodate the bigger K + (1.38 Å) insertion/extraction at extended charge/discharge. [ 4 ] Many efforts have been made to develop anode materials (i.e., carbonaceous materials, [ 5 ] conversion/alloying‐mechanism materials, [ 6 ] organic materials [ 7 ] ) to address these issues.…”