Who will drive electric vehicles, olivine or spinel?

TLDR

Lithium iron phosphate (LFP) and lithium manganese oxide spinel (LMO) are low‑cost, high‑safety cathode materials for Li‑ion batteries, with LFP offering higher gravimetric capacity and LMO providing superior conductivity, and both are being advanced for high‑temperature performance in hybrid and electric vehicles. The study aims to evaluate strategies that improve LFP and LMO cathode performance for near‑future electric vehicle applications. Experimental comparison shows LFP excels at fast charging while LMO delivers better discharge performance, but both suffer high‑temperature capacity fading from metal dissolution, especially with thick electrodes and without electrolyte additives or cathode coatings.

Abstract

Lithium iron phosphate olivine (LFP) and lithium manganese oxide spinel (LMO) are competitive and complementary to each other as cathode materials for lithium ion batteries, especially for use in hybrid electric vehicles and electric vehicles. Interest in these materials, due to their low cost and high safety, has pushed research and development forward and toward high performance in terms of rate capability and capacity retention or cyclability at a high temperature of around 60 °C. From the view point of basic properties, LFP shows a higher gravimetric capacity while LMO has better conductivities, both electrically and ionically. According to our comparison experiments, depending on the material properties and operational potential window, LFP was favored for fast charging while LMO led to better discharge performances. Capacity fading at high temperatures due to metal dissolution was revealed to be the most problematic issue of LFP and LMO-based cells for electric vehicles (EVs), with thicker electrodes, in the case of no additives in the electrolyte and no coating to prevent metal dissolution on cathode materials. Various strategies to enhance the properties of LFP and LMO are ready for the realization of EVs in the near future.