Multifunctional Composite Binder for Thick High-Voltage Cathodes in Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-voltage lithium nickel manganese oxide (LNMO) spinel cathodes offer high energy density and rate capability.
• Increasing cathode thickness is crucial for improving lithium-ion battery (LIB) energy density.
• Conventional polyvinylidene fluoride (PVdF) binders lead to electrolyte decomposition and cathode delamination in thick LNMO cathodes.

Purpose of the Study:

• To develop a novel composite binder for thick high-voltage LNMO cathodes.
• To overcome the limitations of PVdF binders, including oxidative decomposition and delamination.
• To enhance the electrochemical performance and cycle life of LIBs with thick cathodes.

Main Methods:

• Development and testing of a lithium polyacrylate (LiPAA)-sodium alginate (Na-Alg) composite binder series.
• Systematic experimental design to investigate the chemo-mechano-electrochemical relationships in thick cathodes.
• Characterization of cathode adhesion, cohesion, cycle life, cathode-electrolyte interface (CEI), and cell impedance.

Main Results:

• The LiPAA-Na-Alg composite binder demonstrated enhanced cathode adhesion and cohesion.
• The binder formed a passivating layer at the CEI, improving cycle life and lowering cell impedance.
• A specific composition (LiPAA 30 wt %-Na-Alg 70 wt %) showed strong adhesion and stabilized the solid-electrolyte interfacial (SEI) layer on the graphite anode.
• Significant improvements in LIB performance were observed with the novel composite binder.

Conclusions:

• The LiPAA-Na-Alg composite binder effectively addresses the challenges of thick high-voltage LNMO cathodes.
• This novel binder system enhances adhesion, improves interfacial stability, and boosts LIB performance.
• The findings suggest broad applicability of this composite binder for various thick cathode systems in future LIB development.