Arbitrary skin metallization by pencil-writing inspired solid-ink rubbing for advanced energy storage and harvesting

The development of a durable metallic coating on diverse substrates is both intriguing and challenging, particularly in the research of metal-conductive materials for applications such as batteries, soft electronics, and beyond. Herein, by learning from the pencil-writing process, a facile solid-ink rubbing technology (SIR-tech) is invented to address the above challenge. The solid-ink is exampled by rational combination of liquid metal and graphite particles. By harnessing the synergistic effects between rubbing and adhesion, controllable metallic skin is successfully formed onto metals, woods, ceramics, and plastics without limitation in size and shape. Moreover, outperforming pure liquid-metal coating, the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing. The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well. For applications, the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils. Meanwhile, advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from −196 to 120 °C. This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.