A first report on ex-situ synthesis and utilization of pure La4NiLiO8 in emerging high-performance safe batteries

Abstract Layered nickel-rich cathode materials such as LiNi0.5Co0.2Mn0.3O2 (NCM523) possess huge potential in developing high-performance secondary batteries. However, the micron-sized particles of NCM523 in electrode laminates produce spacious interparticle voids (electronically dead zones) which dampen the charge transference and cause bulk material degradation after interaction with the excessive liquid electrolyte within the voids, thus alarming their safe and confident use in batteries. In this context, we hereby ex-situ synthesize a highly electro-ionically conductive pure La4NiLiO8 for potential use as a voids-filling agent in enhancing the electrochemical performance and durability of the layered energy storage NCM523. The morphological and crystallinity analyses in conjunction with the thermal treatments confirm high stability of La4NiLiO8 up to 1150 °C, exceptionally low resistances, and fast charge conduction (335 mS cm−1). A simplistic but scientifically important filling of the inter-particle voids with only 6% of La4NiLiO8 decreases the charge transfer resistance from 103.2 to 19 Ω cm2, increases the discharge capacity from 185 mAh g−1 to 214 mAh g−1 at 0.2C, and enhances the capacity retention from 58.9 to 81.5% (after 500 cycles at 1C). Thus, the excellent physico-thermo-electrochemical characteristics and stability of La4NiLiO8 as a voids-filling agent are highly beneficial for developing high-performance safe secondary batteries.