An Efficient Two-Polymer Binder for High-Performance Silicon Nanoparticle-Based Lithium-Ion Batteries: A Systematic Case Study with Commercial Polyacrylic Acid and Polyvinyl Butyral Polymers

Abstract

Silicon is one of the most promising anode materials for high energy density lithium ion batteries (LIBs) due to its high theoretical capacity and natural abundance. Unfortunately, significant challenges arise due to the large volume change of silicon upon lithiation/delithiation which inhibit its broad commercialization. An advanced binder can, in principle, reversibly buffer the volume change, and maintain strong adhesion toward various components as well as the current collector. In this work, we present the first report on the applicability of polyvinyl butyral (PVB) polymer as a binder component for silicon nanoparticles-based LIBs. Characteristic binder properties of commercial PVB and polyacrylic acid (PAA) polymers are compared. The work focuses on polymer mixtures of PVB polymers with PAA, for an improved binder composition which incorporates their individual advantages. Different ratios of polymers are systematically studied to understand the effect of particular polymer chains, functional groups and mass fractions, on the electrochemical performance. We demonstrate a high-performance polymer mixture which exhibits good binder-particle interaction and strong adhesion to Cu-foil. PAA/PVB-based electrode with a Si loading of ∼1 mg/cm 2 tested between 0.01 and 1.2 V vs. Li/Li + demonstrate specific capacities as high as 2170 mAh/g after the first hundred cycles.

Advances of polymer binders for silicon‐based anodes in high energy density lithium‐ion batteries

“…Besides, a series of PAA‐based polymer binders have been developed for Si‐based anodes through polymerization, 85‐88 blending 89‐96 and post‐modification 64,97,98 methods. Deng et al designed a water‐soluble triblock copolymer polydopamine‐polyacrylic‐polyethylene oxide (PDA‐PAA‐PEO) binder for Si anodes via reversible addition fragmentation chain transfer (RAFT) polymerization and a coupling reaction (Figure 6A).…”

Ending the Chase for a Perfect Binder: Role of Surface Chemistry Variation and its Influence on Silicon Anodes

“…Most of these studies focus on the use of a single binder with a single silicon source that then are subjected to different drying schemes, voltage ranges, cycle number, processing conditions . Others focus on the same base binder with chemical modifications to the backbone or chemical structure or ratio of components . There have been comparably fewer reports investigating two or more binders with the same silicon and the results are often conflicting.…”

A Highly Flexible Yet >300 mAh cm−3 Energy Density Lithium‐Ion Battery Assembled with the Cathode of a Redox‐Active Polyether Binder

“…Some commercial polyvinyl ethers, such as polyvinyl butyral (PVB) and polyvinyl alcohol (PVA), were reported as good binders due to the ether structures . Still, PVB suffers from insufficient stiffness because of the too‐flexible butyl chains, and the hydroxyl groups in PVA may degrade under oxidative conditions . Our strategy is to attach TEMPO as the pendant groups to improve not only redox capacity but also mechanical and chemical robustness as the binder.…”