Perovskite Oxides Alleviate Microstrain and Anion Loss of Radially‐Aligned Ni‐Rich Ncm811 Cathodes under High‐Voltage Operations

Abstract

The energy density of Ni‐rich cathodes is expected to be further unlocked by increasing the cut‐off voltage to above 4.3 V, which nevertheless come with significantly increased irreversible phase transition and abundant side reactions. In this study, the perovskite oxides enhanced radial‐aligned LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes are reported, in which the coherent‐growth La2[LiTM]O4 clusters are evenly riveted into the crystals and the stable LaxCa1−x[TM]O3−x protective layer is concurrently formed on the surface. The reciprocal interactions greatly reduce the lattice strain during de‐/lithiation. Meantime, the abundant oxygen vacancies of the coating layer are proved to reversibly capture (state of charge) and re‐release (state of discharge) the oxygen radicals, fully avoiding their correlative side reactions. The resultant NCM811 displays negligible O2 and CO2 emissions when charging to 4.5 V as well as a thinner CEI film, therefore delivering a large capacity of 225 mAh g−1 at 0.1C in coin‐type half‐cells and a high retention of 88.3% after 1000 cycles at 1C in pouch‐type full‐cells within 2.7–4.5 V. The development of high‐voltage Ni‐rich cathodes exhibits a highly effective pathway to further increase their energy density.

Enhanced Li-ion intercalation kinetics and lattice oxygen stability in single-crystalline Ni-rich Co-poor layered cathodes

“…These results indicate that the stability of Ba–O and Al–O bonds in BA-NCM85 are significantly stronger than the single Ba–O in B-NCM85 and pristine M–O bonds in NCM85, and it has the lowest O vacancy content. 21,33 This was followed by electron paramagnetic resonance spectroscopy (EPR) to further demonstrate the obvious lattice O loss reduction of the BA-NCM85 (Fig. 1g).…”