Cost-Effective Solutions for Lithium-Ion Battery Manufacturing: Comparative Analysis of Olefine and Rubber-Based Alternative Binders for High-Energy Ni-Rich NCM Cathodes

Abstract

Promoting safer and more cost-effective lithium-ion battery manufacturing practices, while also advancing recycling initiatives, is intrinsically tied to reducing reliance on fluorinated polymers like polyvinylidene difluoride (PVDF) as binders and minimizing the use of hazardous and expensive solvents such as N-methyl pyrrolidone (NMP). In pursuit of this objective, olefin- and rubber-based polymers have been investigated as promising alternatives for binder materials in high-energy Ni-rich LiNi_xCo_yMn_zO₂ (NCM, x≥0.8) cathodes for lithium-ion batteries (LIBs). Alternative binders such as polyisobutylene (PIB), poly(styrene-butadiene-styrene) (SBS), nitrile butadiene rubber (NBR), and its hydrogenated version (HNBR) offer versatile solutions. These polymers can be dissolved in industrial solvents, such as toluene, and have been further processed into homogeneous cathode slurries, thus facilitating the manufacturing of high-energy Ni-rich NCM cathodes for lithium-ion batteries. The evaluation of NCM811 cathodes obtained from PIB, SBS, NBR, and HNBR has involved a thorough assessment of their physical and chemical properties, electrochemical performance, and production expenses, compared with NCM811 cathodes based on PVDF. Notably, cathodes employing PIB and HNBR have exhibited outstanding qualities, showcasing high specific capacity and remarkable electrochemical stability akin to PVDF-based counterparts. Furthermore, the alternative binders′ superior adhesion, elasticity, and thermal stability have facilitated obtaining uniform and mechanically stable cathode films. Furthermore, using toluene, with its low vapor pressure, has significantly reduced energy costs associated with drying processes, thereby enhancing the overall cost-effectiveness of the NCM811 cathodes.