Locking-chain electrolyte additive enabling moisture-tolerant electrolytes for sodium-ion batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Unstable electrolyte-electrode interfaces and trace water in organic electrolytes limit battery cycling life.
• Water molecules in electrolytes can trigger detrimental decomposition reactions, reducing battery performance and longevity.

Purpose of the Study:

• To design a novel electrolyte additive, 15PBS, for optimizing battery electrolyte and interface properties.
• To suppress water-induced electrolyte decomposition and improve interfacial stability in sodium-ion batteries.

Main Methods:

• Designed and synthesized a locking-chain molecule: sodium 4,4'-(1,4-phenylenebis(oxy))-bis(butane-1-sulfonate)-15-crown-5 (15PBS).
• Investigated 15PBS's effect on water state within the electrolyte and its adsorption behavior at electrode interfaces.
• Fabricated and tested hard carbon || Na0.72Ni0.32Mn0.68O2 full cells with 15PBS additive.

Main Results:

• 15PBS transforms reactive water into an inactive state, suppressing electrolyte decomposition.
• 15PBS forms a stable, ion-conductive solid electrolyte interphase on hard carbon anodes and cathode surfaces.
• The full cell achieved high specific energy (191.7 Wh kg-1) and long cycle life (2000 cycles at 500 mA g-1).

Conclusions:

• 15PBS effectively optimizes the electrolyte phase and electrode interfaces, enhancing battery durability.
• The additive demonstrates compatibility with lithium-ion battery systems, broadening its applicability.
• This approach offers a pathway to safer, high-performance batteries with extended operational lifespans.