Ecofriendly Preparation of Stable Lithium Iron Phosphate Cathodes for Lithium-ion Batteries

Currently, the cells using Lithium Iron Phosphate (LFP) cathode have attracted more attention due to their temperature stability, durability, safety, and fast-charging capability for lithium-ion batteries (LIBs). The nano-sized LFP cathodes have been well-studied for various applications of LIBs, in particular, electric vehicles and energy storage systems. Herein, we used the open-pore micron-sized LFP material as a cathode using an eco-friendly electrode fabrication process for LIBs. The electrodes have been fabricated using LFP, carbon black, and sodium carboxymethyl cellulose/styrene butadiene rubber binder with various active materials contents (80-85 wt%; LFP80/LFP83/LFP85). These electrodes have been characterized with FTIR, Raman, Peel strength, Swelling, XPS, CV, and EIS analyses. The obtained swelling (18.42%) and peel strength (2.57 N/25 mm) values are on par with the electrodes prepared by the conventional method using a non-aqueous PVDF binder. The existence of Fe2+ in the electrode is confirmed by high-resolution XPS spectra. From EIS, the obtained solution resistance and charge transfer resistance values of the electrodes are comparable to the standard LFP electrode prepared using PVDF binder. LFP80 exhibited an initial discharge capacity of 130.9 mAh g(-1) at 1C-rate with a capacity retention of > 90% after 300 cycles. The electrode shows excellent rate capability, even at 4C-rate, it delivered a capacity of 116.3 mAh g(-1). In addition, the electrode displayed a stable capacity as high as 148.7 and 75.3 mAh g(-1) at 1C-rate at 65 and -10 degrees C, respectively. Hence, the LFP80 electrode prepared by eco-friendly processes can very well be used for versatile LIB applications.