<p>Olivine-type LiFePO₄ is a cornerstone cathode material for lithium-ion batteries, prized for its safety and stability. To advance its applications in extreme conditions, a fundamental understanding of its behavior under high pressure is essential. The present study employs a first-principles approach rooted in density functional theory (DFT) and implemented via Materials Studio software, with the objective of investigating the effects of pressure (0–10 GPa) on the structural, elastic, optical, and thermodynamic properties of LiFePO₄. Structural analysis reveals a decrease in unit cell volume from 290.37 to 280.88 ų and an increase in density from 3.60 to 4.06 g/cm³ with increasing pressure. This indicates systematic lattice contraction. In terms of elasticity, the compliance of the elastic constants with the Born criteria serves to confirm the mechanical stability of the system. The bulk modulus, shear modulus, and Young’s modulus exhibit a substantial increase with pressure, from 87.86 to 111.65 GPa, 49.04 to 61.24 GPa, and 124.05 to 155.33 GPa, respectively, indicating an enhancement in rigidity, hardness, and elastic anisotropy under high pressure. Optically, the real part of the dielectric function decreases from 4.8 to 4.2, and the refractive index increases from 1.70 to 1.80 as pressure rises from 0 to 10 GPa. It is evident that there has been a substantial improvement in the absorption capacity, with a notable shift from 10 to 20 eV, confirming the close correlation between light absorption and photoconductive properties. In accordance with the principles of Thermodynamics, the heat capacity approaches the Dulong-Petit limit as the temperature increases. Concurrently, the entropy decreases as the pressure rises. Furthermore, the Debye temperature rises linearly from 1192.37 to 1438.79 K, indicating enhanced lattice stiffness under compression. This study provides theoretical validation for the utilization of LiFePO₄ in high-pressure environments.</p>