10: Aqueous Binders in Lithium-Ion Batteries

Hi everyone! In this post, I will look at some new improvements for binders in LIBs, such as water-soluble binders.

Improvements

Lithium-ion batteries are widely used in various applications but need improved binders to enhance their performance to meet evolving demands. This is because silicon oxide (SiO), a promising anode material due to its high capacity and low cost, faces several challenges. These include poor conductivity, which leads to slower charging rates, and significant expansion during charging.

Polyvinylphosphonic Acid

A recent study utilized polyvinylphosphonic acid (PVPA) as a binder for a micro-SiO electrodes, achieving superior performance compared to conventional cells. The study produced electrodes containing PVPA, PAA, and PVDF as binders, and their performance was assessed through electrochemical experiments and density functional theory. PVPA demonstrated notably stronger adhesion (3.44 N/m) to a copper support compared to conventional PAA (2.03 N/m), leading to significantly enhanced durability in lithium-ion batteries.

The PVPA-based cell also delivered almost twice the discharging capacity compared to the PAA-based cell after 200 cycles, with the PVPA-based half-cell achieving 1300 mAhg-1SiO after the same cycle count. Even after 200 cycles of charge-discharge, exfoliation from the current collector was not observed in scanning electron microscopy, unlike with PVDF or PAA binders. Furthermore, the stronger adhesion of PVPA helps stabilize the SiO-based anode, preventing its exfoliation even with significant volume expansion.

The study concluded that PVPA binder should be very useful in extending the life of high-performing lithium-ion secondary batteries. Particularly in the application of electric vehicles, there has been intense interest in enabling long life for lithium-ion secondary batteries. The use of PVPA will offer improved alternatives to commercially available binders, such as polyacrylic acid (PAA) and polyvinylidene fluoride.

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