High-capacity semi-organic polymer batteries: From monomer to battery in an all-aqueous process

Aqueous Zinc-batteries comprising organic cathode materials represent interesting candidates for sustainable, safe, environmentally friendly, and highly flexible secondary energy storage system. Here, we demonstrate that such an oxygen-tolerant, semi-organic setup can conveniently be prepared in an all-aqueous process, including all steps from the initial polymerization to the coin cell assembly without the need of any intermediate purification steps, and still reach high energy densities of 2.55 mAh cm−2. The TEMPO-modified and crosslinked poly(methacrylamide) cathode facilitates an excellent compatibility to the aqueous electrolyte and an efficient accessibility of the redox-active species due to the increased polarity of the material compared to the common poly(TEMPO-methacrylate) (PTMA). The material exhibits excellent stability (capacity retention of >99% after 1000 cycles at 5C) with low self-discharge and features high rate capabilities. The casting process from the aqueous slurry further appeared to be suitable for the preparation of ultra-thick but still homogeneous binder-free electrodes and exhibit total device capacities of approximately 4.5 mAh in a 2032-type coin cell. Since the overall process avoids harsh conditions or harmful solvents, is scalable, and relies on straightforward processing steps, it represents a promising step towards cost-effective and efficient rechargeable Zinc-based semi-organic batteries with competing capacities if further optimized.