Aqueous zinc-ion batteries have gained significant interest, offering several distinct advantages over conventional lithium-ion batteries owing to their compelling low cost, enhanced battery safety, and excellent environmental friendliness. Nevertheless, the unfortunate growth of zinc dendrites during cycling leads to poor electrochemical performance of zinc batteries, primarily attributed to the diminished wet mechanical properties and limited electrolyte uptake of existing commercial separators. Herein, a bio-based separator was developed from sustainable resources using natural polymers derived from wood pulp to replace fossil-based polyolefin separators. The inherent hydrophilicity and swelling ability of cellulose fibers provide separators with superior electrolyte wettability and uptake. Notably, the structural reinforcement provided by lignin, especially after hot pressing, enhances the separator's wet mechanical integrity and performance during battery cycling. These improvements contribute to the separator's more stable electrochemical performance and improved ion transport properties. Separators composed of lignin-rich microfibrillated cellulose fibers showed superior dimensional stability under heat compared to Celgard, ensuring higher thermal safety and enhanced performance of aqueous zinc-ion batteries. Our results reveal the great potential of lignin-rich cellulose-based separators for future zincion batteries.

Polymer binder selection greatly impacts electrode performance, production, and recyclability in batteries and energy storage systems. We introduce a novel family of polymer binders that provide several key advantages over traditional binders in Li-ion batteries. Our findings show that in-situ cross-linked networks of eco-friendly polyesters bearing pendant carboxylic moieties can serve as superior binders for electrodes. When tested specifically in high‑silicon-content anodes, the electrodes exhibit high initial coulombic efficiency and sustain impressive specific capacity retention after 300 cycles. They reach approximately 2500 mAh/g, compared to 1580 mAh/g for electrodes using conventional PAA binders. Furthermore, the anode shows stable cycling performance when paired with NMC532 cathodes in full Li-ion cell tests. Notably, the transition of silicon from intermediate phases to its fully lithiated state is more efficient with the polyester binder, attributed to the formation of a more stable solid-electrolyte interphase (SEI) layer and reduced impedance. We assign the high performance of our binder to the presence of the polar groups, e.g. carbonyl, in the primary polymer chain, along with the end functional moieties, promoting Li+ solvation and transport, resulting in a high ionic conductivity of the binder. Moreover, the inherent flexibility in the formulations of the polyesters enables fine-tuning of properties such as adhesion, elasticity, and a suitable glass transition temperature, all of which could be customized to optimize battery performance. Produced from renewable feedstocks and adopting water-based or solvent-free fabrication processes, these polyesters offer a fully sustainable solution from production to recycling at the end of the battery's life.

Designing an efficient, durable, and inexpensive bifunctional electrocatalyst toward oxygen evolution reactions (OER) and oxygen reduction reactions (ORR) remains a significant challenge for the development of rechargeable zinc-air batteries (ZABs). The generation of oxygen vacancies plays a vital role in modifying the surface properties of transition-metal-oxides (TMOs) and thus optimizing their electrocatalytic performances. Herein, a H2/Ar plasma is employed to generate abundant oxygen vacancies at the surfaces of NiCo2O4 nanowires. Compared with the Ar plasma, the H2/Ar plasma generated more oxygen vacancies at the catalyst surface owing to the synergic effect of the Ar-related ions and H-radicals in the plasma. As a result, the NiCo2O4 catalyst treated for 7.5 min in H2/Ar plasma exhibited the best bifunctional electrocatalytic activities and its gap potential between Ej = 10 for OER and E1/2 for ORR is even smaller than that of the noble-metal-based catalyst. In situ electrochemical experiments are also conducted to reveal the proposed mechanisms for the enhanced electrocatalytic performance. The rechargeable ZABs, when equipped with cathodes utilizing the aforementioned catalyst, achieved an outstanding charge–discharge gap, as well as superior cycling stability, outperforming batteries employing noble-metal catalyst counterparts.

A noble-metal-free bifunctional electrocatalyst with outstanding activity and stability is of great importance for the development of rechargeable zinc-air batteries (ZABs). Herein, we employed a facile strategy to fabricate nitrogen-doped NiCo2O4 nanostructures on carbon paper as a binder-free air cathode for rechargeable ZABs. An optimized process of nitrogen plasma treatment has enhanced the electrical conductivity of the metal oxide and induced abundant active sites into the crystal structures, resulting in enhanced electrocatalytic activities toward oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Notably, mild plasma treatment leads to efficient N doping while the morphology and specific surface area of the catalyst both remain unchanged. The air cathode with NiCo2O4 doped with nitrogen in 2 min plasma treatment and integrated into a zinc-air battery with liquid electrolyte provided a small charge-discharge voltage gap and distinguished cycling stability superior to the air cathode with noble-metal catalyst counterparts. Furthermore, the solid-state zinc-air battery with this material displays excellent stability with just a small increase of the charge-discharge voltage gap over 20 h of operation. This work illustrates the promising potential of plasma treatment in the fabrication of high-performance catalysts.