SYNTHESIS OF PRECURSOR MATERIALS OF LITHIUM NMC 811 BATTERY CATHODE USING NICKEL SULPHATE FROM DOMESTIC NICKEL ORE REFINING AND ANALYSIS OF ITS ELECTROCHEMICAL PERFORMANCE

• Main Author: Surya Wijareni, Anisa
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/66553
• Institution: Institut Teknologi Bandung

In the era of transition from fossil fuel vehicles to electric vehicles, the need for Lithium-ion batteries is increasing. The use of battery-based electric vehicles is an option to reduce greenhouse gas (CO2) emissions resulting from fossil fuel vehicles that have an impact on global warming. The performance of Li-ion batteries is highly dependent on the performance of the electrodes, especially the cathode. One of the cathode materials that are predicted to be widely used in Li-ion batteries is LiNixMnyCozO2 or known by the abbreviation NMC. In this study, the process of synthesizing the cathode material for the Li-NMC 811 battery with the coprecipitation method and testing the electrochemical performance of the NMC 811 battery cell, where there are 3 types of nickel sources as the constituent material for the NMC 811 cathode material, namely nickel sulfate produced from the extraction and refining of nickel laterite ore from Sulawesi Island, commercial nickel sulfate and MHP (Mixed Hydroxide Precipitate). The research begins with the preparation of the cathode constituent material according to the specified variation. After each sulfate salts (NiSO4.6H2O, CoSO4.7H2O and MnSO4.H2O) were prepared based on its designed mass according to NMC 811 stoichiometry, then the salts were mixed in 2M oxalic acid (H2C2O4) as precipitation medium with the addition of NH4OH solution as a pH controller. The material was stirred for 2 hours after reaching a temperature of 60? with a speed of 200 rpm. The solution was allowed to stand and washed until the pH was neutral, filtered, and dried. The product of the co-precipitation process was then calcined at 600? for 6 hours and sintered at 800? for 12 hours with oxygen gas injection to produce 3 types of precursor materials with 3 different nickel sources, namely SK-LNMCO-811 (using technical grade nickel sulfate from the market), SM-LNMCO-811 (using MHP as nickel source) and SX-LNMCO-811 (using nickel sulfate from the MHP refining process). The battery cells were fabricated with 3 types of cathode precursors with graphite anodes and a commercial precursor (K-NMC code 811) was used as a comparison. The experimental results showed that the synthesized material had a Ni:Mn:Co molar ratio close to 8:1:1 with a chemical structure of LiNi0,8Mn0,1Co0,1O2 and a trigonal crystal structure (hexagonal axes). Figure of Merit (FoM) of the precursor crystall structure using nickel sulfate from the synthesis process (SX-LNMCO-811) is the most similar with the commercial precursor K-NMC-811 with a similarity of 98.7%. The particle size and particle distribution on D10, D50 and D90 obtained from PSA (Particle Size Analysis) result using nickel sulfate synthesis product (SXLNMCO- 811) were similar to those of the commercial precursor K-NMC-811. Samples K-NMC-811 and SX-LNMCO-811 had almost the same mean particle size values, namely 18.28 m and 17.16 m, respectively. The particle size of the NMC 811 cathode precursor is in accordance with previous research results, which was in the range of 15-20 m. The results of the FTIR (Fourier Transform Infrared) analysis showed the suitability of the compound groups formed after the coprecipitation stage, namely the formation of O-H and C-O bonds. The results of the analysis of the synthesis product after calcination and sintering that resulted in the dissociation of carbonate and oxalate from the mixed of M-oxalate-lithium carbonate by releasing CO2 gas are indicated by the FTIR results with weakening (sloping) O-H, C-O and carbonate bonds (CO32-). Morphological characterization using SEM of LiNi0,8Mn0,1Co0,1O2 particles with synthesized nickel sulfate showed the shape of SX-LNMCO-811 particles which tended to be spherical and most similar to the commercial precursor sample K-NMC-811. The results of the SEMEDS (Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy) mapping identified the distribution of the elements Ni, Mn, and Co on the particles. The best electrochemical performance of the full battery LiNi0,8Mn0,1Co0,1O2 is shown by the battery cell with the code of SX-LNMCO-811 which uses synthesized nickel sulfate as a nickel source, which is 178.93 mAh/g with an efficiency of 4.32%. The best value for the diffusion coefficient in the SX-LNMCO-811 sample is 4,22 x 10-9 cm2/s and the CV (Cyclic Voltammetry) results show that each sample has an oxidation peak and a reduction peak that correlates with the charge-discharge reversibility.