A Safer Sodium-Ion Battery Based on Nonflammable Organic Phosphate Electrolyte

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries offer a cost-effective alternative to lithium-ion batteries for grid-scale energy storage.
• Safety concerns, particularly electrolyte flammability, hinder the widespread adoption of sodium-ion batteries.
• Development of nonflammable electrolytes is crucial for practical and safe sodium-ion battery applications.

Purpose of the Study:

• To propose and investigate a safer sodium-ion battery system utilizing a nonflammable phosphate electrolyte.
• To evaluate the compatibility and performance of trimethyl phosphate (TMP) electrolyte with specific cathode and anode materials.
• To demonstrate the feasibility of a nonflammable sodium-ion battery for large-scale energy storage.

Main Methods:

• Investigated the physical and electrochemical properties of trimethyl phosphate (TMP) electrolyte with FEC additive.
• Conducted flammability tests, ionic conductivity measurements, cyclic voltammetry, and charge-discharge cycling.
• Fabricated and tested a prototype sodium-ion battery cell using Sb anode, NaNi_0.35Mn_0.35Fe_0.3O₂ cathode, and TMP + 10 vol% FEC electrolyte.

Main Results:

• The TMP + FEC electrolyte was found to be nonflammable with a wide electrochemical window (0-4.5 V vs. Na/Na+).
• Both the Sb-based anode and NaNi_0.35Mn_0.35Fe_0.3O₂ cathode exhibited high reversible capacity and good cycling stability in the TMP electrolyte.
• The constructed nonflammable sodium-ion battery demonstrated considerable capacity and cyclability.

Conclusions:

• Trimethyl phosphate (TMP) based electrolytes, when combined with FEC additive, offer a safe and viable alternative to conventional carbonate electrolytes for sodium-ion batteries.
• The developed Sb//NaNi_0.35Mn_0.35Fe_0.3O₂//TMP+FEC system shows significant promise for safer, large-scale energy storage solutions.
• This research paves the way for the commercialization of safer sodium-ion battery technologies.