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Summary: With the impact of the COVID-19 lockdown, global supply chain crisis, and Russo-Ukrainian war, an energy-intensive society with sustainable, secure, affordable, and recyclable rechargeable batteries is increasingly out of reach. As demand soars, recent prototypes have shown that anode-free configurations, especially anode-free sodium metal batteries, offer realistic alternatives that are better than lithium-ion batteries in terms of energy density, cost, carbon footprint, and sustainability. This Perspective explores the current state of research on improving the performance of anode-free Na metal batteries from five key fields, as well as the impact on upstream industries compared to commercial batteries.

The electroreduction of nitrogen to ammonia offers a promising alternative to the Haber–Bosch process but suffers from low activity and selectivity. Here, authors demonstrate that triggering a salting-out effect in a highly concentrated electrolyte can achieve highly efficient ammonia synthesis.

Supercapacitor electrodes composed of a 3D V2O5 network with polypyrrole (PPy) uniformly decorated onto each nanowire were fabricated to enhance their pseudocapacitive performance. The continuous 3D network creates channels for better ion transport, and the high degree of pore connectivity in the network enhances the mass transport. The PPy shell could enhance the electric conductivity and prevent the dissolution of vanadium. These merits together with the ideal synergy between V2O5 and PPy lead to a high specific capacitance of 448 F g- which is three times higher than that of the stacked V2O5. The all-solid-state symmetric supercapacitor device assembled by the V2O5/PPy core/shell 3D network exhibits a high energy density (14.2 W h kg-1) at a power density of 250 W kg1 and good cyclic stability (capacitance retention of 81% after 1000 cycles). Furthermore, the prepared device could power a red light-emitting diode indicator efficiently after charging for only 10 s. [ABSTRACT FROM AUTHOR]

It is highly challenging to explore high–performance bi-functional oxygen electrode catalysts for their practical application in next-generation energy storage and conversion devices. In this work, we synthesize hierarchical N–doped carbon microspheres with porous yolk–shell structure (NCYS) as a metal-free electrocatalyst toward efficient oxygen reduction through a template-free route. The enhanced oxygen reduction performances in both alkaline and acid media profit well from the porous yolk–shell structure as well as abundant nitrogen functional groups. Furthermore, such yolk–shell microspheres can be used as precursor materials to motivate the oxygen reduction activity of oxygen evolution oriented materials to obtain a desirable bi-functional electrocatalyst. To verify its practical utility, Zn–air battery tests are conducted and exhibit satisfactory performance, indicating that this constructed concept for preparation of bi-functional catalyst will afford a promising strategy for exploring novel metal–air battery electrocatalysts. [ABSTRACT FROM AUTHOR]

We introduce a new method for fabricating unique on-chip supercapacitors based on CuO/polypyrrole core/shell nanosheet arrays by means of direct electrochemical co-deposition on interdigital-like electrodes. The prepared all-solid-state device demonstrates exceptionally high specific capacitance of 1275.5 F cm−3 (∼40 times larger than that of CuO-only supercapacitors) and high-energy-density of 28.35 mWh cm−3, which are both significantly greater than other solid-state supercapacitors. More importantly, the device maintains approximately 100% capacity retention at 2.5 A cm−3 after 3000 cycles. The in situ co-deposition of CuO/polypyrrole nanosheets on interdigital substrate enables effective charge transport, electrode fabrication integrity, and device integration. Because of their high energy, power density, and stable cycling stability, these newly developed on-chip supercapacitors permit fast, reliable applications in portable and miniaturized electronic devices. [ABSTRACT FROM AUTHOR]