Advanced engineering of Nd-doped LiNMC hybrid supercapacitor materials with planetary ballmill method and DEM-based microstructural simulation

Abstract

This study investigates the role of neodymium oxide (Nd₂O₃) doping in enhancing the performance and durability of LiNi_0.8Mn_0.1Co_0.1O₂(NMC811) cathode materials for advanced energy storage applications. Using the Discrete Element Method (DEM), the effects of milling parameters, such as particle shape, rotation speed, and ball-to-powder diameter ratio (BPDR), were simulated in a planetary ball mill. FTIR analysis identified characteristic M-O bonds (Ni-O, Co-O, Mn-O) within 400–700 cm⁻¹. XRD characterization confirmed the successful synthesis of the rhombohedral NMC811 phase (R3m space group) after sintering at 850 °C for 12 h. Morphological analysis revealed a predominantly spherical structure, enhancing ion transport efficiency and reducing internal resistance. Cyclic voltammetry (CV) with a potential range of −0.7 to −0.1 V showed oxidation and reduction peaks at approximately −0.3 V and −0.5 V, respectively. Nd doping significantly increased the specific capacitance from 44.20 F/g for undoped LiNMC811 to 67.34 F/g at 0.9 % Nd doping. However, power density decreased from 74.35 W/kg to 50.92 W/kg for the same doping level, highlighting a trade-off between ion transport and power delivery. Efficiency after 500 charge-discharge cycles demonstrated optimal retention for undoped NMC811 at 100 %, decreasing to 80.01 % at 0.3 % Nd doping and recovering to 85.73 % at 0.6 % Nd doping before slightly dropping to 83.35 % at 0.9 % Nd doping. DEM simulation in 500 RPM, the mechanical system operates under low energy and stress conditions, with a moderate compressive load and minimal torque.