Although alkaline zinc-manganese dioxide batteries have dominated the primary battery applications, it is challenging to make them rechargeable. Here we report a high-performance rechargeable zinc-manganese dioxide system with an aqueous mild-acidic zinc triflate electrolyte. We demonstrate that the tunnel structured manganese dioxide polymorphs undergo a phase transition to layered zinc-buserite on first discharging, thus allowing subsequent intercalation of zinc cations in the latter structure. Based on this electrode mechanism, we formulate an aqueous zinc/manganese triflate electrolyte that enables the formation of a protective porous manganese oxide layer. The cathode exhibits a high reversible capacity of 225 mAh g−1 and long-term cyclability with 94% capacity retention over 2000 cycles. Remarkably, the pouch zinc-manganese dioxide battery delivers a total energy density of 75.2 Wh kg−1. As a result of the superior battery performance, the high safety of aqueous electrolyte, the facile cell assembly and the cost benefit of the source materials, this zinc-manganese dioxide system is believed to be promising for large-scale energy storage applications.

Sodium-ion batteries (SIBs) have attracted great interest for large-scale electric energy storage in recent years. However, anodes with long cycle life and large reversible capacities are still lacking and therefore limiting the development of SIBs. Here, a bulk Bi anode with surprisingly high Na storage performance in combination with glyme-based electrolytes is reported. This study shows that the bulk Bi electrode is gradually developed into a porous integrity during initial cycling, which is totally different from that in carbonate-based electrolytes and ensures facile Na transport and structural stability. The achievable capacity of bulk Bi in the NaPF -diglyme electrolyte is high up to 400 mAh g , and the capacity retention is 94.4% after 2000 cycles, corresponding to a capacity loss of 0.0028% per cycle. It exhibits two flat discharge/charge plateaus at 0.67/0.77 and 0.46/0.64 V, ascribed to the typical two-phase reactions of Bi ↔ NaBi and NaBi ↔ Na Bi, respectively. The excellent performance is attributed to the unique porous integrity, stable solid electrolyte interface, and good electrode wettability of glymes. This interplay between electrolyte and electrode to boost Na storage performance will pave a new pathway for high-performance SIBs.

Rechargeable aqueous zinc batteries (RAZBs) are promising for large-scale energy storage because of superiority in addressing cost and safety concerns. However, their practical realization is hampered by the issues including...

No abstract

No abstract

Organic electrode materials suffer from low electronic conductivity and poor structure stability.H erein, ametal-organic polymer,Ni-coordinated tetramino-benzoquinone (Ni-TABQ), is synthesized via d-p hybridization. The polymer chains are stitched by hydrogen bonds to feature as arobust two-dimensional (2D) layered structure.Itoffers both electron conduction and Na + diffusion pathwaysa long the directions of the polymer chains and the hydrogen bonds.With both the conjugated benzoidcarbonyls and imines as the redox centers for the insertion and extraction of Na + ,t he Ni-TABQ delivers high capacities of about 469.5 mAh g À1 at 100 mA g À1 and 345.4 mAh g À1 at 8Ag À1 .The large capacities are sustained for 100 cycles with almost 100 %c oulombic efficiencies.T he exceptional electrochemical performance is attributed to the unique 2D electron conduction and Na + diffusion pathways enabled by the robust Ni-N and hydrogen bonds.

Li−O 2 batteries are considered the ultimate energy storage technology for their potential to store large amounts of electrical energy in a cost-effective and simple platform. Large overpotentials for the formation and oxidation of Li 2 O 2 during discharging and charging have thus far confined this technology to a scientific curiosity. Herein, we consider the role of catalytic intervention in the reversibility of the cathode reactions and find that semiconducting metal−organic polymer nanosheets composed of cobalt-tetramino-benzoquinone (Co-TABQ) function as a bifunctional catalyst that facilitates the kinetics of the cathode reactions under visible light. Upon discharging, we report that O 2 is first adsorbed on the Co atoms of Co-TABQ and accepts electrons under illumination from the d z 2 and d xz orbitals of Co atoms in the π 2p * orbitals, which facilitates reduction to LiO 2 . The LiO 2 is further shown to undergo a second reduction to the discharge product of Li 2 O 2 . In the reverse charge, the holes generated in the d z 2 orbitals of Co are mobilized under the action of the applied voltage to enable the fast decomposition of Li 2 O 2 to O 2 and Li + . Under illumination, the Li−O 2 battery exhibits respective discharge and charge voltages of 3.12 and 3.32 V for a round-trip efficiency of 94.0%. Our findings imply that the orbital interaction of metal ions with ligands in Co-TABQ nanosheets dictates the light harvesting and oxygen electrocatalysis for the Li−O 2 battery.

A scalable and binder-free Cu2Sb/Cu electrode has been synthesized via replacement reaction as an anode for sodium-ion batteries (SIBs). The thickness of Cu2Sb formed on Cu foil can be facilely tuned by adjusting the concentration of Sb3+ and reaction time. A high capacity of 318.4 mAh g–1 is obtained at 0.08 A g–1, and a capacity retention of 98.5% is also maintained after 200 cycles at 0.8 A g–1. The reaction mechanism of the as-synthesized Cu2Sb/Cu is investigated by using ex situ X-ray diffraction and transmission electron microscopy. The porous Cu2Sb nanoparticle film and its intrinsic contact with the Cu foil result in the good electrochemical performance. This facile synthetic route for the integrity of Cu2Sb nanoparticles and Cu foil allow for simplifying the preparation processes of SIBs in large-scale applications and is applicable for advanced material design and synthesis.