Drying of Compact and Porous NCM Cathode Electrodes in Different Multilayer Architectures: Influence of Layer Configuration and Drying Rate on Electrode Properties

Abstract

Porous, nanostructured particles ensure the wetting of electrolyte up to the particle core and shortened diffusion paths, which is relevant not only for lithium‐ion batteries but also for postlithium systems like sodium‐ion batteries. The porous structure leads to a high C‐rate capability. However, compared to conventional compact NCM, porous NCM shows a reduced adhesion force but no or only slight negative influence on C‐rate capability by binder migration at higher drying rates. Herein, a multilayer concept is used to increase the adhesion force with equal or better electrochemical performance compared to single‐layer electrodes. Compact particles of high volumetric energy density and porous particles with high C‐rate capability are combined in a simultaneously coated multilayer electrode. Multilayers with compact NCM toward the current collector and porous NCM with reduced binder content toward the separator side show an about 16‐times higher adhesion force at lower drying rate and an about ten‐times higher adhesion force at increased drying rate compared to electrodes produced of porous NCM only. The specific discharge capacity of the multilayers is increased by 88% at the lower and 67% at the higher drying rate for a discharge rate of 3C compared to a single layer with compact NCM.

About drying phenomena of fuel cell and electrolyzer CCM inks: Selectivity of the evaporation of 1‐propanol/water mixtures

“…Afterward, the solvents evaporate inside the pores among the particles (Figure 1c). The microstructure is formed depending on the drying conditions [36][37][38][39][40][41][42][43][44][45][46]. When the film solidifies, cracks may form in the dry electrode (Figure 1d) [47,48].…”

Enabling Long-term Cycling Stability of Na3V2(PO4)3/C vs. Hard Carbon Full-cells

“…The electrodes investigated originate from large-scale processing developed in cooperation with several institutes of KIT. [34][35][36] A detailed description focusing on NVP/C processing was recently provided by Klemens et al 37 and here we briefly summarize the process. The slurry for NVP/C cathodes was mixed in a dissolver (Dispermat SN-10, VMA Getzmann), where carbon black (C65, C-Nergy) and graphite (KS6L, Timical-Imerys), a PVDF (Solef 5130, Solvay) binder-solvent solution with 7.5 wt.% and about 50 % of the required amount of NMP were dispersed.…”

“…In a last mixing step, styrene-butadiene rubber (SBR, Zeon Europe) was added. The electrode coating and drying was carried out under quasi-isothermal drying conditions as a discontinuous process likewise described by Klemens et al [34][35][36][37] The slurries were applied to an aluminum current collector by a doctor blade (ZUA 2000.60, Zehntner) and dried by an impingement dryer and temperature controlled heating plates, resulting in drying rates of 0.75 g m -2 s -1 in both cases. After drying, the electrodes were calendered at 50 °C.…”

Application of Multistage Drying Profiles for Accelerated Production of Li‐Ion Battery Anodes Using Infrared Radiation: Validation with Electrochemical Performance and Structural Properties

“…Some studies reveal that the application of multilayer architecture electrodes with individually adapted binder proportions, particle sizes, shapes or particle porosities can counteract the effects of decreasing adhesion as well as decreasing capacities. [18,19] Another promising approach to oppose low adhesion values is the use of primer coatings with high binder contents. [2,20] Yet, a further concept that serves as the main basis for the study presented is the application of multistage drying profiles as introduced by Jaiser et al which could be applied to achieve a time saving of about 40%.…”