Hierarchical Li-rich oxide microspheres assembled from {010} exposed primary grains for high-rate lithium-ion batteries

Abstract

Layered Li-rich oxides (LLOs) with high capacity exceeding 300 mA h g⁻¹ and low cost are regarded as the most promising candidates for high energy-density (500 W h kg⁻¹) lithium-ion batteries. However, they usually present sluggish Li⁺ kinetics and low tap-density, resulting in poor rate capability and volumetric energy density. Here, the wide particle size distribution of LLO microspheres assembled from {010} exposed primary grains is rationally proposed to solve the above-mentioned issues. A high specific capability of ∼295 mA h g⁻¹ at 0.1C and superior cycling stability (capacity retention of 90.6% after 100 cycles) are achieved. The close stacking caused by the coexistence of large and small secondary particles gives rise to a high tap-density of 2.26 g cm⁻³, corresponding to a high volumetric energy density of above 2350 W h L⁻¹. The TEM results confirm that the lateral direction nanosheets belong to the electrochemically active {010} planes, which further results in the improved Li⁺ kinetics during redox. As a result, an excellent high-rate capability of 110 mA h g⁻¹ is achieved even at 20C. The GITT tests elucidate that the active {010} exposed planes exhibit superior Li⁺ diffusion kinetics during charge and discharge processes. This feasible strategy can be expanded to enhancing the Li⁺ kinetics of other NCM-based layered cathodes for alkali rechargeable batteries.