Cellulose nanofiber-reinforced solid polymer electrolytes with high ionic conductivity for lithium batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Lithium metal batteries offer high energy density but suffer from dendrite formation, limiting their practical use.
• Solid polymer electrolytes (SPEs) can mitigate dendrite growth but often compromise ionic conductivity due to required stiffness.

Purpose of the Study:

• To develop a composite SPE that decouples stiffness and ionic conductivity for improved lithium metal battery performance.
• To investigate the use of cellulose nanofibers (CNFs) as a stiffening agent in a soft polymer matrix.

Main Methods:

• A composite SPE was fabricated using a soft poly(ethylene oxide-co-epichlorohydrin) (EO-co-EPI) copolymer and stiff cellulose nanofibers (CNFs).
• The mechanical properties (storage modulus) and ionic conductivity of the composite SPE were evaluated.
• Electrochemical stability and cycling performance in lithium metal batteries were assessed.

Main Results:

• CNF reinforcement significantly increased the storage modulus of the SPE by up to three orders of magnitude.
• The composite SPE maintained high ionic conductivity comparable to the neat polymer electrolyte.
• The material demonstrated good cycling stability and electrochemical performance in lithium metal battery tests.

Conclusions:

• The developed composite SPE effectively balances mechanical stiffness and ionic conductivity, addressing key limitations in lithium metal battery electrolytes.
• This cellulose nanofiber-reinforced polymer electrolyte shows significant promise for enabling safer and higher-performance lithium metal batteries.