Performance Evaluation of FeS Anodes For Li-ion Batteries: From Fundamentals To Multilayer Pouch Cells

Conversion-type materials for lithium-ion anodes usually combine high lithiation and delithiation capacities with limited cycling performance. Herein, the aqueous processing and testing of iron sulfide (FeS) anodes are addressed. These electrodes were initially developed at the laboratory scale to gain knowledge of their manufacturability and electrochemical performance in half and full coin cells. The recipe was scaled up to a semi-industrial coating line, and the electrodes manufactured were used to assemble multilayer pouch cells with LiNi0.6Mn0.2Co0.2O2 cathodes. These cells were subjected to rate-capability tests and cycling at different temperatures. The experiments at 45ºC had to be stopped due to excessive gas generation, while the results at 25ºC were similar to those observed in full coin cells. The post-mortem characterization of the electrodes utilizing X-ray photoelectron spectroscopy revealed sulfur shuttling from the anode to the cathode and redeposition at its surface. Thus, loss of anode active material as a degradation mechanism has been identified. All in all, the implementation of a novel and promising conversion material on an industrially relevant scale is demonstrated for the first time, and some strategies to tackle the issues detected are proposed.