The Rate Capability Performance of High-Areal-Capacity Water-Based NMC811 Electrodes: The Role of Binders and Current Collectors

Abstract

The aqueous processing of cathode materials for lithium-ion batteries (LIBs) has both environmental and cost benefits. However, high-loading, water-based electrodes from the layered oxides (e.g., NMC) typically exhibit worse electrochemical performance than NMP-based electrodes. In this work, primary, binary, and ternary binder mixtures of aqueous binders such as CMC, PAA, PEO, SBR, and Na alginate, in combination with bare and C-coated Al current collectors, were explored, aiming to improve the rate capability performance of NMC811 electrodes with high areal capacity (≥4 mAh cm−2) and low binder content (3 wt.%). Electrodes with a ternary binder composition (CMC:PAA:SBR) have the best performance with bare Al current collectors, attaining a specific capacity of 150 mAh g−1 at 1C. Using carbon-coated Al current collectors results in improved performance for both water- and NMP-based electrodes. This is further accentuated for Na-Alg and CMC:PAA binder compositions. These electrodes show specific capacities of 170 and 80 mAh g−1 at 1C and 2C, respectively. Although the specific capacities at 1C are comparable to those for NMP-PVDF electrodes, they are approximately 50% higher at the 2C rate. This study aims to contribute to the development of sustainably processed NMC electrodes for high energy density LIBs using water as solvent.

Keywords

• NMC811
• aqueous processing
• high-loading electrodes
• water-based electrodes
• aqueous binders
• carbon-coated aluminum current collector