Polyacrylonitrile Based Triblock Copolymer Binder Enabling Excellent Performance toward LiNi_0.5Mn_1.5O₄ and Sulfur...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• High energy density lithium-ion batteries are crucial for electric vehicles and advanced electronics.
• Spinel LiNi0.5Mn1.5O4 (LNMO) offers high voltage and capacity but suffers from binder degradation at high potentials.
• Conventional binders like polyvinylidene fluoride (PVDF) exhibit poor stability, leading to capacity fading.

Purpose of the Study:

• To develop a novel binder that enhances the electrochemical performance and cycle life of LNMO cathodes.
• To investigate the impact of a new triblock copolymer binder on electrode integrity and voltage resistance.
• To address the limitations of conventional binders in high-voltage lithium-ion battery applications.

Main Methods:

• Solution polymerization was used to synthesize the triblock poly(acrylonitrile-methyl methacrylate-acrylic anhydride) (PAMA) binder.
• The PAMA binder's mechanical properties (peeling strength) were compared to polyvinylidene fluoride (PVDF).
• Electrochemical performance, including capacity retention and cycle life, was evaluated for LNMO cathodes using PAMA and PVDF binders.

Main Results:

• The PAMA binder demonstrated significantly higher peeling strength (0.506 N cm-1) than PVDF (0.3 N cm-1).
• LNMO electrodes with PAMA binder retained 70.7% capacity after 800 cycles, compared to 33.9% for PVDF.
• The PAMA binder's polar groups facilitated lithium polysulfide adsorption, suppressing the shuttle effect in sulfur-modified electrodes (S@PAMA).

Conclusions:

• The PAMA binder offers superior binding energy and electrochemical stability for high-voltage LNMO cathodes.
• PAMA significantly improves the cycle life and capacity retention of lithium-ion batteries.
• This novel binder presents a promising strategy for developing next-generation high-energy-density batteries.