Nanostructured LiNi0.80Co0.15Al0.05O2 (NCA) for Fast-Charging, High-Capacity Cathodes

Abstract

Nanostructuring, which shortens lithium-ion diffusion lengths, can help facilitate pseudocapacitive behavior in some battery materials. Here nanostructured LiNi0.80Co0.15Al0.05O2 (NCA), with porosity and decreased crystallite size compared to commercial bulk NCA, was synthesized using a colloidal polymer template. Small particles (~150 nm) were obtained using rapid thermal annealing (RTA), while medium particles (~300 nm) were obtained with conventional heating. X-ray photoelectron spectroscopy (XPS) was used to quantify surface Li2CO3 and NiO-like contaminants, which hinder lithium-ion diffusion, especially at fast rates. Electrochemical kinetics studies were used to quantify the benefits associated with nanostructuring. While all nanostructured samples displayed faster charge/discharge kinetic compared to the bulk materials, NCA with medium particle sizes showed the highest specific capacity at the fast rates (150 mAh/g at 16C). To explore full-cell behavior, nanostructured NCA was paired with a pseudocapacitive anode, achieving 95 Wh/kg energy density at a current density of 1260 W/kg and stable cycling for 2000 cycles at 10C.