Next-generation wearables will interface intimately with the human body either on-skin, implanted or woven into clothing. This requires electrical components that match the mechanical properties of biological tissues - stretchability (up to 60% strain) and softness (Youngs modulus of similar to 1 kPa to 1 MPa). As wearables become increasingly complex, the energy and mechanical requirements will increase, and an integrated power supply unit such as a soft and stretchable battery is needed to achieve autonomy and wireless operation. However, two key challenges remain for current stretchable battery technology: the mechanical performance (softness and stretchability) and its relation to the size and charge storage capacity (challenge I), and the sustainability and biocompatibility of the battery materials and its components (challenge II). Integrating all these factors into the battery design often leads to a trade-off between the various properties. This perspective will evaluate current strategies for achieving sustainable stretchable batteries and provide a discussion on possible avenues for future research. Stretchable battery technology still faces several challenges to progress the development of next-generation wearables. This perspective will evaluate current strategies and provide a discussion on possible avenues for future research.