NO₃^--Mediated Solvent Immobilization in Medium-Concentration Ether-Based Electrolytes: Enabling High-Voltage Lithium...

Area of Science:

• Electrochemistry and Materials Science
• Energy Storage Systems

Background:

• Ether-based electrolytes are promising for high-energy-density lithium metal batteries.
• Challenges include poor oxidative stability at high voltages (>4.3 V) and limited temperature range.
• Instability arises from interfacial issues with lithium metal anodes and high-voltage cathodes.

Purpose of the Study:

• To develop an innovative solvent immobilization strategy for ether electrolytes.
• To enhance oxidative stability and interfacial compatibility for lithium metal batteries.
• To enable stable battery operation at high voltages and across extreme temperatures.

Main Methods:

• Formation of a "bead string" structure via self-assembly of nitrate anions (NO₃^-) and long-chain ether solvents.
• Immobilization of solvent molecules within the bulk electrolyte.
• Creation of an anion-rich electric double layer (EDL) at 1.5 M concentration.

Main Results:

• A stable, inorganic-dominated passivation layer formed on lithium metal anodes and high-voltage cathodes.
• Exceptional cycling stability demonstrated in Li || LiCoO₂ and Li || NCM811 batteries at high voltages (up to 4.45 V).
• Successful operation across an ultrawide temperature range (-60 to 70 °C).

Conclusions:

• The solvent immobilization strategy effectively enhances ether electrolyte stability.
• The "bead string" structure and resulting passivation layer are key to improved performance.
• This approach offers a viable solution for high-energy-density lithium metal batteries operating under demanding conditions.