Synergy Between Weak Solvent and Solid Electrolyte Interphase Enables High-Rate and Temperature-Resilient Potassium...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Graphite-based potassium-ion batteries (PIBs) face limitations in rate capability and wide-temperature performance due to sluggish interfacial kinetics and unstable solid electrolyte interphase (SEI) layers.
• Efficient K+ ion transport and stable SEI formation are critical for advancing PIB technology.

Purpose of the Study:

• To design weak solvating electrolytes (WSEs) that promote efficient K+ desolvation and a stable, K2SO3-rich SEI.
• To enhance the reaction kinetics at the electrode interface through synergistic interactions between the SEI and WSEs.
• To achieve high rate performance and cycling stability in graphite-based PIBs across a wide temperature range.

Main Methods:

• Strategic design of weak solvating electrolytes (WSEs).
• Construction of a K2SO3-rich solid electrolyte interphase (SEI) on graphite anodes.
• Electrochemical testing of graphite anodes and potassium-ion cells (KC8||K-PBNPs) under various conditions.

Main Results:

• The designed WSEs facilitated efficient K+ desolvation and formed a stable SEI, leading to fast interfacial reaction kinetics.
• Graphite anodes exhibited excellent rate performance (249.6 mAh g-1 at 500 mA g-1) and cycling stability (96.6% retention after 1600 cycles).
• Assembled KC8||K-PBNPs cells demonstrated high-rate capability (63.1 mAh g-1 at 1500 mA g-1) and exceptional wide-temperature performance (over 99% Coulombic efficiency at -20°C and 80°C).
• Pouch cells achieved long-term stability with 2400 cycles at 500 mA g-1.

Conclusions:

• The synergy between SEI components and WSEs is crucial for overcoming kinetic limitations in PIBs.
• The developed WSEs enable fast-charging and temperature-resilient potassium-ion battery technology.
• This research provides a pathway for developing high-performance and durable potassium-ion batteries.