Aqueous multifunctional binder boosting high energy and thermal safety of Na3V2(PO4)3

Abstract

The conventional cathode processing utilizes a polyvinylidene fluoride/N-methyl-2-pyrrolidone (PVDF/NMP) binder system, which is afflicted by its toxic and mutagenic characteristics, as well as inadequate binding strength. Furthermore, the protracted drying rate of NMP results in uneven accumulation and gradient distribution of cathode materials throughout the extended drying process, thereby adversely impacting electron and ion transport as well as the integrity of the interface structure. This study introduces polyethyleneimine (PEI) as an aqueous multifunctional binder, which enhances the adhesion between electrode materials, improves mechanical stability, and reduces material detachment and damage, thereby extending the lifespan of Na₃V₂(PO₄)₃ (NVP). Concurrently, PEI can regulate the particle distribution and structure of electrodes, optimize the porosity and charge transport pathways, and improve the energy density and cycling stability of NVP. Furthermore, PEI exhibits superior thermal stability at elevated temperatures, enhancing the reliability of battery performance in high-temperature environments. Leveraging these advantages, the application of PEI as a binder in this study has the potential to augment the energy density, cycle life, and safety of batteries, thereby offering a novel approach for optimizing sodium-ion batteries (SIBs) and advancing the development of battery technology.