In recent years, due to the increased sensitivity towards the theme of sustainability, lithium-ion batteries have grown interest as well-established potential solutions for replacing fossil fuels. For this reason, different ways to optimize battery technologies have been covered. One idea is based on the concept of massless energy storage and is represented in practice by structural lithium-ion batteries, multifunctional systems that provide satisfying electrochemical and thermomechanical properties at the same time. The basic components of batteries have been redesigned. Electrodes made of carbon fibres are now at an advanced stage of research, while the electrolyte has not been optimized yet. Bicontinuous electrolytes have been obtained through polymerization-induced phase separation to ensure appreciable ionic conductivity and stiffness, thanks to the cooperative work of the polymer network and the liquid percolating phase.