Lithium-ion batteries (LIBs) have widely been applied in electronic devices due to their high energy densities, flexible design, light weight, and long lifespan compared to other types of batteries. Gas generation or the volume swelling of a battery is a common phenomenon of lithium-ion battery performance degradation. This is usually caused by electrolyte degradation during the lifespan of lithium-ion batteries. Knowing the composition of swelling gas is critical to optimizing the electrolyte composition. Lithium battery electrolyte is the carrier of ion transport in a lithium battery, which is generally composed of lithium salt and organic solvent. In the electrolyte, the commonly used lithium salt is LiPF6, and the solvent is a binary, ternary, or multinary system composed of a mixture of cyclic carbonates and chain carbonates. Selecting the right organic electrolyte is the key to achieving a higher energy density, a longer cycle life, and greater battery safety. In this presentation we will discuss two separate methods utilizing the Agilent 990 micro-GC and the Agilent single quadrupole GC/MSD for analysis of swelling gas and carbonate solvents and additives in lithium-ion batteries.