Today's mobile devices powered by batteries have kept feeding users endless entertainment and convenience, whereas always accompanied by some unfavorable experiences that is 'Always have to recharge'. The puzzle of battery life has been an inevitable limitation that could probably degrade user experience, even though smartphones, smart homes, and smart wearables are growing ever more advanced. A new technology named 'Energy Harvesting' emerges. As an enabler of battery-less devices, it has exceptional potential in replacing the battery as the power source for future mobile devices. On the other hand, however, accompanied by enormous potential, energy harvesting will also bring tremendous concerns. Current mobile device users have equipped the knowledge of handling the limited battery life and formulated a cognition towards energy in battery-based devices. In other words, the Current Energy partnership, meaning the interactive and cognitive relations between users and energy in battery-based devices, is built on the battery capacity limitation. However, such a partnership will not be compatible with the non-battery devices in which battery life is no longer a limitation. The central aim of this research has been to explore the current and future Energy Partnership between users and future intermittently powered devices. The Research-through-Design methodology has been employed, embracing online surveys, user interviews, prototypes design, and user tests to launch a collaborative discussion with interviewees about the possibilities of the future Energy Partnership. From a set of user studies and a systematic integration of previous research, the current EP Model is proposed to demonstrating the interactive and cognition process between users and the energy in battery-based mobile devices. The research found that the current energy partnership can be conceptualized as a balance between user and appropriate usage time. Building on the current EP Model and insights distilled from expert interviews, a hypothetical EP Model has been developed, articulating the transformation of Energy Partnership brought by energy harvesting technology. The hypothesis was then iterated twice through designing and testing the prototype simulating the energy behavior of intermittently powered devices.