Fabrication of flexible and stretchable highly conductive Ag-PDMS tri-layer interconnect and its integration into Li-ion pouch cells

Devices of the 2
^st
century have transformed from rigid handheld usage to their thin, flexible, and stretchable counterparts. Potential applications of such devices include soft robotics for gaming and virtual reality, sensors for body movement and health monitoring, flexible displays, and others. With this transition, the need for different components of such devices to be flexible has increased several folds. Such components should be able to conform to any shape while bending, flexing, or stretching while maintaining their mechanical integrity and electrical stability. Hence, reliability is of utmost importance. While energy storage research and application has already been witnessing a shift to high performance yet flexible Li-ion batteries, conventional rigid metal tabs continue to be used as interconnects becoming their failure point. Highly conductive fillers introduced into soft polymer matrix are often the chosen solution to design flexible and stretchable conductors to avoid a trade-off between mechanical and electrical requirements. In this work, a low-cost method to produce thin yet highly conductive flexible and stretchable interconnect is proposed. This thin interconnect can be batch fabricated for industrial applications. Extensive reliability testing is performed to assert its reproducibility and durability. The prepared interconnect is integrated into Li-ion pouch cell to study the effect of pouch sealing conditions on its mechanical and electrical properties and reversibly the effect of this novel interconnect on seal strength. In this paper, the design of the tri-layer interconnect and batch fabrication along with standalone and battery pouch integrated interconnect characterization and reliability testing methods are discussed in detail.