Mechanoadaptive morphing gel electrolyte enables flexible and fast-charging Zn-ion batteries with outstanding dendrite suppression performance

The safe, flexible, and environment-friendly Zn-ion batteries have aroused great interests nowadays. Nevertheless, flagrant Zn dendrite uncontrollably grows in liquid electrolytes due to insufficient surface protection, which severely impedes the future applications of Zn-ion batteries especially at high current densities. Gel electrolytes are emerging to tackle this issue, yet the required high modulus for inhibiting dendrite growth as well as concurrent poor interfacial contact with roughened Zn electrodes are not easily reconcilable to regulate the fragile Zn/Zn2+ interface. Here we demonstrate, such a conflict may be defeated by using a mechanoadaptive cellulose nanofibril-based morphing gel electrolyte (MorphGE), which synergizes bulk compliance for optimizing interfacial contact as well as high modulus for suppressing dendrite formation. Moreover, by anchoring desolvated Zn2+ on cellulose nanofibrils, the side reactions which induce dendrite formation are also significantly reduced. As a result, the MorphGE-based symmetrical Zn-ion battery demonstrated outstanding stability for more than 100 h at the high current density of 10 mA·cm−2 and areal capacity of 10 mA·h·cm−2, and the corresponding Zn-ion battery delivered a prominent specific capacity of 100 mA·h·g−1 for more than 500 cycles at 20 C. The present example of engineering the mechanoadaptivity of gel electrolytes will shed light on a new pathway for designing highly safe and flexible energy storage devices.