Lignin-based matrices for self-healable and environmental friendly potassium batteries

Rechargeable batteries are a key technology in the world rush toward the energy transition. Li-ion batteries (LIBs) have reached unprecedent targets of performance and safety, nevertheless it is not logical to think that the LIB technology only is able to bear the world electrification, given the lithium scarcity (0.0017 wt% in the Earth crust) and its uneven distribution. It is therefore not surprising the increasing attention coming from the research community on potassium-based batteries. Potassium is abundant on Earth (2.09 wt%), evenly distributed, characterized by a very low standard equilibrium potential (-2.93 V vs. SHE with respect to -3.09 V vs. SHE of Li+/Li) and Lewis acidity (smaller solvated ions and thus faster conduction) [2]. K-ion batteries (KIBs) already proved to have all the requirements for large stationary storage systems. In this scenario and keeping in mind the sustainability of this technology, our groups work on the design, synthesis and characterization of fully biobased polymers for KIB electrolytes. In this contribution, lignin-based gel polymer electrolytes are proposed. Once the membrane is activated by soaking liquid electrolyte, the as obtained gel polymer electrolyte has been fully characterized showing suitable ionic conductivity exceeding 10-3 S cm-1, excellent chemical compatibility and tremendous ability at suppressing the growth of metal dendrites. Its further implementation with molecular functionalities aiming at guaranteeing self-healing capacity is investigated and lab-scale cells cycling for more that 1000 cycles are demonstrated.