At low temperatures, the power and capacity characteristics of lithium-ion batteries (LIBs) deteriorate significantly. Furthermore, low-temperature charging can induce lithium plating on the surface of graphite particles in the battery anode, resulting in irreversible damage. To enhance the low-temperature performance of LIBs, two approaches can be adopted. The first focuses on optimizing the electrolyte and the cathode and anode materials to enhance the intrinsic low-temperature performance of the batteries. The second approach involves designing thermal management solutions tailored to meet automotive requirements. While advancements in electrolyte composition and electrode materials can improve the low-temperature performance of LIBs, such developments are typically experimental and unlikely to achieve significant breakthroughs in the short term, making them insufficient to meet current automotive demands. One effective strategy to address this challenge is the low-temperature alternating current (AC) heating, which uses AC excitation to leverage the internal impedance of the battery for rapid heating. This method offers advantages such as low energy consumption, uniform temperature distribution, low cost, and high heating efficiency. This chapter focuses on the AC heating theory and principles for automotive LIBs. It begins by introducing the thermal characteristics used for AC heating temperature calculations, emphasizing the mechanisms of heat generation, transfer, and dissipation. Among these, the heat generation mechanism plays a fundamental role in temperature rise during AC heating and is primarily influenced by battery impedance. However, at low temperatures, the electrode processes in LIBs exhibit strong nonlinear behavior, as battery impedance is affected by multiple factors, including current amplitude and temperature. To address this complexity, this chapter investigates the nonlinear relationship between battery impedance, current, and temperature. The relationships between impedance, temperature, and current amplitude are modeled using the Arrhenius equation and the Butler–Volmer equation. Finally, the chapter examines the effects of two commonly used AC heating waveforms—sinusoidal AC heating and bidirectional pulse current (BPC) heating—on battery temperature rise.