Rechargeable Na-CO 2 batteries are considered to be an effective way to address the energy crisis and greenhouse effect due to their dual functions of CO 2 fixation/utilization and energy storage. However, the insolubility and irreversibility of solid discharge products lead to poor discharge capacity and poor cycle performance. Herein, a novel strategy is proposed to enhance the electrochemical performance of hybrid Na-CO 2 batteries, using water-in-salt electrolyte (WiSE) to establish an optimal reaction environment, regulate the CO 2 reduction pathway, and ultimately convert the discharge product of the battery from Na 2 CO 3 to formic acid (HCOOH). This strategy effectively resolves the issue of poor reversibility, allowing the battery to exhibit excellent cycle performance (over 1200 cycles at 30 °C), especially under low-temperature conditions (2534 cycles at −20 °C). Furthermore, density functional theory (DFT) calculations and experiments indicate that by adjusting the relative concentration of H/O atoms at the electrolyte/catalyst interface, the CO 2 reduction pathway in the battery can be regulated, thus effectively enhancing CO 2 capture capability and consequently achieving an ultra-high discharge specific capacity of 148.1 mAh cm −2 . This work effectively promotes the practical application of hybrid Na-CO 2 batteries and shall provide a guidance for converting CO 2 into products with high-value-added chemicals.
Designing catalytic cathodes with excellent electrocatalytic activities and durability for Na-CO 2 batteries has captured considerable attention so far. Here, a series of morphologically controlled low-crystalline CuCo 2 O 4 was prepared by thermal oxidation of self-assembled Cu-Co precursors ( p -CCO). One-dimensional (1D) rod-like of CuCo 2 O 4 was subsequently encapsulated in polypyrrole shell (PPy) by in-situ polymerization of pyrrole monomers as an advanced catalyst (CCO/PPy) for high-performance Na-CO 2 batteries . It was demonstrated that ammonia solution exerts an important influence on the surface morphology and size of the p -CCO crystallites by the rate of nucleation and growth. Particle size and 1D architecture modulation, associated with the encapsulation of conductive PPy effectively improve the directional transfer rate of ions and the conductivity of the electrode. More importantly, PPy introduction not only induces interfacial reconstruction of CuCo 2 O 4 , arousing more oxygen vacancies and catalytic active sites, but also contributes to the corrosion protection of the active material from the electrolyte during long-term operation. Bestowed by these advantages, the fabricated hybrid Na-CO 2 battery manifested prominent electrochemical performance with a superior areal discharge capacity of 31.3 mAh cm −2 , low discharge-charge voltage gap of 0.6 V, over 400 cycles.
危险品化学品经营许可证（带存储）