High-Modulus Hexagonal Boron Nitride Nanoplatelet Gel Electrolytes for Solid-State Rechargeable Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid-state electrolytes are promising for rechargeable lithium-ion batteries, offering enhanced safety and favorable properties.
• Current gel electrolytes have low mechanical strength, leading to poor structural integrity and risk of short-circuiting, especially with lithium dendrite growth.
• Hexagonal boron nitride (hBN) is explored as a reinforcing agent in gel electrolytes.

Purpose of the Study:

• To develop high-modulus, ion-conductive gel electrolytes for solid-state rechargeable lithium-ion batteries.
• To investigate the effect of exfoliated hBN nanoplatelets on the mechanical and electrochemical properties of gel electrolytes.
• To enable high-rate and high-temperature operation of lithium-ion batteries.

Main Methods:

• Synthesis of gel electrolytes incorporating imidazolium ionic liquids and exfoliated hexagonal boron nitride (hBN) nanoplatelets.
• Characterization of mechanical properties (shear storage modulus) and ionic conductivity at room temperature.
• Evaluation of compatibility with high-voltage cathodes and thermal stability for battery operation.

Main Results:

• Exfoliated hBN nanoplatelets improved gel electrolyte mechanical properties by two orders of magnitude (shear storage modulus ~5 MPa).
• High ionic conductivity (>1 mS cm⁻¹) was maintained at room temperature.
• The electrolytes demonstrated compatibility with high-voltage cathodes (>5 V vs Li/Li⁺) and exceptional thermal stability.

Conclusions:

• Exfoliated hBN nanoplatelets significantly enhance the mechanical integrity and thermal stability of ionic liquid-based gel electrolytes.
• These improved gel electrolytes enable high-rate operation of solid-state rechargeable lithium-ion batteries up to 175 °C.
• The developed electrolytes offer a promising pathway for safer and more robust solid-state lithium-ion battery technology.