The performance of energy materials is determined by how they are fabricated and by the depth to which they are understood, and links among synthesis, structure, and device behavior are established through complementary characterization. Common routes such as sol–gel, hydrothermal, Pechini or citrate gel, coprecipitation, combustion, spray pyrolysis, and solid-state diffusion are compared by the control they provide over phase purity, particle size, porosity, and defect chemistry. The resulting microstructures are shown to govern ion and electron transport, stability, and electrochemical activity in batteries, supercapacitors, fuel cells, and photovoltaics. Questions are matched to tools: diffraction with X-ray diffraction (XRD) and neutron methods to resolve crystal structure and polymorphs, microscopy with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) to map morphology and interfaces, spectroscopy with energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and Raman to quantify composition and bonding, thermal analysis with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to probe stability and transitions, and electrochemical diagnostics with cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) to read out kinetics and durability. Recent case studies are used to illustrate how targeted synthesis parameters translate into gains, and the use of multimodal and operando measurements is emphasized to guide verification and iteration toward reliable, scalable performance.