There is a compelling need for innovative design concepts in energy storage devices such as flexible and stretchable batteries that can simultaneously provide electrochemical and mechanical functions to accommodate nonconventional applications including wearable and implantable devices. In this study, we report on the design and fabrication of a stretchable spiral thin-film lithium ion battery that is capable of large out-of-plane deformation of 1300% while exhibiting simultaneous electrochemical functionality. The spiral battery is fabricated using a flexible solid polymer nanocomposite electrolyte film that offers enhanced safety and stability compared to the conventional organic liquid-based electrolyte. The spiral lithium ion battery exhibits robust mechanical stretchability over 9000 stretching cycles and an energy density of 4.862 mWh/cm3 at ∼650% out-of-plane deformation. Finite element analysis of the spiral battery offers insights about the nature of stresses and strains during battery stretching.