Comparative Evaluation of LMR-NCM and NCA Cathode Active Materials in Multilayer Lithium-Ion Pouch Cells: Part I. Production, Electrode Characterization, and Formation

Abstract

A lithium- and manganese-rich layered transition metal oxide (LMR-NCM) cathode active material (CAM) is processed on a pilot production line and assembled with graphite anodes to ≈7 Ah multilayer pouch cells. Each production step is outlined in detail and compared to NCA/graphite reference cells. Using laboratory coin cell data for different CAM loadings and cathode porosities, a simple calculation tool to extrapolate and optimize the energy density of multilayer pouch cells is presented and validated. Scanning electron microscopy and mercury porosimetry measurements of the cathodes elucidate the effect of the CAM morphology on the calendering process and explain the difficulty of achieving commonly used cathode porosities with LMR-NCM cathodes. Since LMR-NCMs exhibit strong gassing during the first cycles, a modified formation procedure based on on-line electrochemical mass spectroscopy is developed that allows stable cycling of LMR-NCM in multilayer pouch cells. After formation and degassing, LMR-NCM/graphite pouch cells have a 30% higher CAM-specific capacity and a ≈5%–10% higher cell-level energy density at a rate of C/10 compared to NCA/graphite cells. Rate capability, long-term cycling, and thermal behavior of the pouch cells in comparison with laboratory coin cells are investigated in Part II of this work.

Gradient porosity electrodes for fast charging lithium-ion batteries

“…Regardless of the porous structure, the intrusion curves of both electrodes demonstrate a slope followed by a plateau in the low-pressure region of <0.04 MPa, characteristic of large pores (>30 μm) constructed of packed electrode pieces. 35,36 From middle to high pressure, the intrusion curve of both electrodes shows three-step incremental changes followed by a horizontal plateau at high pressure, indicative of the variety of pore size distributions in the electrodes. This is corroborated by the analysis of the pore size distribution (PSD).…”

Implications of the Heat Generation of LMR-NCM on the Thermal Behavior of Large-Format Lithium-Ion Batteries

“…For a specific application, including its corresponding load profile, an optimal cell design and operating strategy for the thermal management system could be derived. 24,27 The material properties were taken from data sheets and literature. 14,31,51 Journal of The Electrochemical Society, 2021 168 053505 following equations calculate the total density tot r , the heat capacity c p,tot , the through-plane thermal conductivity k^, and the in-plane thermal conductivity k  based on the respective layer thicknesses l. 14,31,47 The corresponding material properties are listed in Table A•I.…”

“…26 In our previous publication, multilayer LMR-NCM/graphite and NCA/graphite pouch cells with a nominal capacity of around 6-7 Ah were manufactured on the pilot scale production line at the Technical University of Munich. 27 The C/10 voltage profiles of an LMR-NCM/ graphite pouch cell are displayed in Fig. 1.…”

Qualifying water-based electrode dispersions for the inkjet printing process: a requirements analysis

“…Electrode production begins with the blending of the components in a sequence of dry and wet mixing processes to obtain a homogeneous dispersion (Schreiner et al , 2021). In addition to the electrode components, the dispersion contains volatile additives and solvents.…”