Self-Healing Stretchable Li-Ion Battery Based on a High-Voltage Hydrogel Electrolyte

Safe and deformable batteries that can be conformally embedded onto irregular surfaces of electrical systems and human body are desirable for wearable electronic applications due to low user friction. Commercial state-of-the-art Li-ion batteries are packaged in rigid hermetic sealing materials that are not deformable. State-of-the-art deformable Li-ion batteries reported in research articles show fast degradeation due to severe performance problems such as the penetration of moisture and the leakage of toxic and inflammable electrolytes. Here we report a non-toxic, aqueous hydrogel electrolyte instead of its organic counterpart that is demonstrated to: 1) enable highly safe operations due to its non-toxic and non-flammable nature; 2) alleviate the moisture penetration problem from outside environment; (3) have a high-voltage working window of ~2.8V; and (4) allow the construction of stretchable batteries by using elastic polymer packaging materials instead of rigid hermetic seals. In the prototype tests, fabricated batteries have shown good stretchability (50% strain) and flexibility (radius of curvature < 2mm) to enable conformal attachments to a wide range of geometric surfaces. The prototype battery also shows outstanding cyclic stability, retaining ~90% of the original capacity after 100 cycles for over 2 months in the ambient environment without using any rigid hermetic sealing package. Finally, a prototype battery with a self-healing elastomer package remains functional after being punctured by a needle 5 times at different locations through the package. Furthermore, it can recover >90% of its capacity after being cut through by a razor blade and subsequently healed at 70 for 10 minutes. Such safe and highly stretchable batteries would be useful for several wearable electronic applications such as blood glucose monitoring, hear rate monitoring , temperature monitoring, wireless charging, smart clothing, etc.