An electrochemically paralleled biomass electrolyte additive facilitates the integrated modification of multi-dimensional Zn metal batteries

A diverse array of Zn metal batteries (ZMBs) are swiftly emerging as a prominent force in the energy storage sector. Electrolyte modification is integral to improving the performance of ZMBs by effectively optimizing the behavior of both the anode and cathode. However, most existing electrolytes are specifically tailored to individual battery systems, thereby limiting their broader applicability across different ZMB technologies. Herein, a universal electrolyte additive design strategy, termed “electrochemical parallelism”, has been proposed to address this issue. By addressing critical challenges such as poor reversibility of the Zn anode, severe pH fluctuation at the MnO₂ electrode/electrolyte interface, solvent evaporation in open systems, and corrosion induced by polyiodide ions, a multifunctional pyrrolidone carboxylate sodium (PCA-Na) additive is developed. Its integrated functionalities include Zn anode interfacial modification, Zn²⁺ solvation regulation, pH buffering, hydrogen bond network restructuring and polyiodide ion repulsion. As a result, it enables the Zn anode of a symmetric pouch cell with a cumulative plating capacity of 704 A h, a Zn‖MnO₂ pouch cell with a discharge capacity exceeding 370 mA h, a Zn-air battery with an electrolyte shelf life surpassing 1000 h, and a 3.7 A h-level Zn‖I₂ pouch cell with a capacity retention of 83% after 130 cycles. These advancements collectively realize the electrochemical parallel integration of ZMBs.