Uncovering Charge Accumulation Dynamics in Contact Electrification

Contact electrification between material pairs is a ubiquitous phenomenon in nature, typically involving two processes, charge transfer and accumulation. The mechanism of charge transfer has been extensively explored and gradually understood. However, charge accumulation is still elusive. Here, we developed a synergistic approach integrating macro- and microscales to complementarily uncover the charge accumulation and accumulation dynamics in contact electrification. The charge accumulation process is confirmed to be always divided into two stages, including the initial rapid accumulation caused by the growth of contact charge density and later slow accumulation determined by an increase in contact area, respectively. A dynamic equation of contact charge accumulation is established, which provided a general guideline for accurately anticipating and manipulating the accumulation of contact charges. Consequently, the accumulation velocity of contact charge reaching saturation can be controllably increased from 9.9 × 10 –4 to 5.9 × 10 –3 μA/cycle with an improvement of 6 times by designing contact materials.