The demand for lithium-ion batteries (LIBs) is projected to increase significantly in the coming years, driven primarily by the increased use of electric vehicles (EV) and renewable energy storage systems. According to a recent study, the demand for LIBs could reach 10,000 GWh by 2040, and meeting this demand just through mining has significant challenges due to limited primary resources. Thus, achieving a sustainable Li supply depends on the presence of well-established recycling procedures for end-of-life LIBs. Among various chemistries of LIBs, NMC chemistry (Li[NixMnyCoz]O2) is the most popular choice when it comes to EV and energy storage systems. NMCbased LIBs come in several variants defined by their Ni:Mn:Co ratios e.g., NMC111 (Li[Ni0.33Mn0.33Co0.33]O2). Recent efforts to reduce Co content in NMC batteries, due to its high cost and ethical concerns, have led to the development of high Ni variants such as NMC622 (Li[Ni0.6Mn0.2Co0.2]O₂). It is estimated that, by 2050, the production of NMC-based LIBs from primary resources to fulfill the future demand will lead to the emission of greenhouse gases totaling 8.2 GtCO2eq. Thus, sustainable recycling of NMC-based end-of-life LIBs by recovering valuable metals such as Li, Ni, Mn, and Co will not only reduce the burden on primary resources but also minimize the environmental impacts. Another valuable component of end-of-life LIBs is graphite (anode) which has been classified as a critical raw material. It accounts for ~40 % of LIBs by weight and recycling graphite has also gained traction recently. Recycling end-of-life LIBs usually begins with the preparation of black mass, which is produced by safely discharging, shredding, grinding, and then milling the end-of-life LIBs. Black mass (BM), a fine powder, contains valuables such as Li, Ni, Mn, Co, graphite, and small amounts of Al and Cu current collectors. Material characterization techniques are significant in developing sustainable and efficient pre-treatment and recycling processes for end-of-life LIBs. These techniques offer critical insights into the physicochemical properties of valuables in BM and allow for investigating the effects of pre-treatment and recycling processes, thereby providing a data-driven framework to design and optimize efficient recycling strategies. Pre-treatment of BM is crucial due to the presence of impurities such as residual electrolytes, polyvinylidene fluoride (PVDF) binder, carbon black, and other organic species deposited on the surface of cathode active material (CAM) and graphite. Removal of PVDF binder is highly desirable as it can adversely affect recycling efficiency by depositing on the surface of CAM particles. Mechanical pre-treatment methods such as ball milling are used to liberate the CAM and graphite particles, while also reducing the particle size to the desired value. Attrition milling is another example where the surface impurities are removed without affecting the particle size. Pyrolysis of BM has also been used extensively as a pretreatment process as it can decompose PVDF binder, electrolytes, and other organic impurities. Pre-treated BM is then subjected to hydrometallurgical recycling processes e.g., leaching and froth flotation. Since Li in pyrolyzed BM is highly water-soluble, water leaching is used to leach out Li. Froth flotation is used to recover graphite from pyrolyzed BM with appreciable efficiency since the hydrophobic surface of graphite particles and the hydrophilic surface of CAM are now exposed after pyrolysis. Pyrolysis pre-treatment also causes phase change of NMC (Li[NixMnyCoz]O2) particles by reducing them into individual metal (Ni, Mn, Co) oxides. Characterization techniques are essential in assessing the effects of these pre-treatment methods and allow for further optimization of the recycling processes. Particle size distribution (PSD) is one of the key parameters in the recycling of BM, as it is influenced by pre-treatment methods (e.g., milling) and affects further recycling processes (e.g., leaching and flotation). Laser diffraction technique is widely used for PSD measurements of BM due to its well-established methodology, ability to handle wide size ranges, and rapid acquisition. However, it does not readily enable real-time measurements, in-situ measurements, or handle highly concentrated samples. Real-time monitoring of particle size is vital for studying the underlying mechanisms of recycling processes (e.g., leaching and flotation). Focused Beam Reflectance Measurement (FBRM) technology offers a solution by measurements of chord length distribution (CLD). Another critical factor influencing recycling processes is the phase chemistry of both NMC cathode and graphite anode in BM, investigated using X-ray diffraction (XRD). XRD can be used to study crystalline phases of Li, graphite, and NMC. However, precise identification of exact NMC phases as well as differentiation between different phases of graphite using qualitative XRD analysis is challenging due to overlapping peaks. Scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM/EDS) can be employed to complement XRD by visualizing local morphology and identifying NMC phase composition. Meanwhile, Raman spectroscopy offers crucial insights into disordered or amorphous carbon species deposited on the surface of graphite particles, however, it requires careful profile fitting and data analysis. To overcome these combined limitations, correlating data from all techniques is essential. Thermogravimetric analysis (TGA) coupled with mass spectrometry (MS) is another effective technique for characterizing carbonaceous materials such as BM. A qualitative analysis of the pyrolysis mechanism of BM under inert TGA/MS conditions has been explored in prior studies. However, a quantitative analysis of the TGA/MS results to obtain useful information and quantify carbonaceous species remains challenging for BM samples. In this study, these characterization techniques have been used collectively to assess the physicochemical properties of three different BM samples, examine the effect of pre-treatment methods (e.g., pyrolysis), and provide a clear basis for planning recycling strategies. The FBRM technique is used to develop a method for the measurement of chord length for BM samples by comparing the effects of different weighting methods with PSD measurements. FBRM technique can overcome shortcomings of PSD measurements from laser diffraction technique and allow for real-time analysis of pre-treatment and recycling processes. A quantitative analysis of TGA/MS under an oxidative atmosphere has been carried out to determine the amount (wt. %) of graphite in BM samples. This method is developed using pure graphite as a reference to prepare a calibration curve. Furthermore, the estimation of PVDF binder (wt. %) using TGA/MS under an oxidative atmosphere is also discussed while SEM/EDS is used to visualize the distribution of PVDF binder on the surface of active particles. A procedure to analyze the residual electrolytes and other organic species in BM using TGA/MS (under an inert atmosphere) is also defined. An overview of XRD patterns of three different BM samples is provided in this study and necessary structural parameters (e.g., peak position, crystalline phase, hkl index, and reference) are summarized for reference. The main findings from XRD analysis are correlated with the metal composition (wt. %) and SEM/EDS data to study the phase chemistry and composition of the NMC cathode. Furthermore, graphite particles are examined using Raman spectroscopy to provide a clear distinction between different types of graphite surfaces based on a spectral feature called ID/IG ratio (i.e., a ratio of the D band to the G band). These characterization techniques, when used together, offer a thorough understanding of BM samples, enabling the development of efficient pre-treatment and recycling processes.