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

This study investigates the role of neodymium oxide (Nd2O3) doping in enhancing the performance and dura bility of LiNi0.8Mn0.1Co0.1O2(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 char acteristic M-O bonds (Ni-O, Co-O, Mn-O) within 400–700 cm1. XRD characterization confirmed the successful synthesis of the rhombohedral NMC811 phase (R3m space group) after sintering at 850 ◦C for 12 h. Morpho logical 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