Review of the use of transition-metal-oxide and conducting polymer-based fibres for high-performance supercapacitors

Heteroatom doped graphene engineering for energy storage and conversion

Rocking-chair based lithium-ion batteries (LIBs) have extensively applied to consumer electronics and electric vehicles (EVs) for solving the present worldwide issues of fossil fuel exhaustion and environmental pollution. However, due to the growing unprecedented demand of LIBs for commercialization in EVs and grid-scale energy storage stations, and a shortage of lithium and cobalt, the increasing cost gives impetus to exploit low-cost rechargeable battery systems. Dual-ion batteries (DIBs), in which both cations and anions are involved in the electrochemical redox reaction, are one of the most promising candidates to meet the low-cost requirements of commercial applications, because of their high working voltage, excellent safety, and environmental friendliness compared to conventional rocking-chair based LIBs. However, DIB technologies are only at the stage of fundamental research and considerable effort is required to improve the energy density and cycle life further. We review the development history and current situation, and discuss the reaction kinetics involved in DIBs, including various anionic intercalation mechanism of cathodes, and the reactions at the anodes including intercalation and alloying to explore promising strategies towards low-cost DIBs with high performance.

Strategies towards Low-Cost Dual-Ion Batteries with High Performance.

Mechanically stable and foldable air cathodes with exceptional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities are key components of wearable metal-air batteries Herein, a directional freeze-casting and annealing approach is reported for the construction of a 3D honeycomb nanostructured, N,P-doped carbon aerogel incorporating in situ grown FeP/Fe2 O3 nanoparticles as the cathode in a flexible Zn-air battery (ZAB) The aqueous rechargeable Zn-air batteries assembled with this carbon aerogel exhibit a remarkable specific capacity of 648 mAh g-1 at a current density of 20 mA cm-2 with a good long-term durability, outperforming those assembled with commercial Pt/C+RuO2 catalyst Furthermore, such a foldable carbon aerogel with directional channels can serve as a freestanding air cathode for flexible solid-state Zn-air batteries without the use of carbon paper/cloth and additives, giving a specific capacity of 676 mAh g-1 and an energy density of 517 Wh kg-1 at 5 mA cm-2 together with good cycling stability This work offers a new strategy to design and synthesize highly effective bifunctional air cathodes to be applied in electrochemical energy devices

An Iron-Decorated Carbon Aerogel for Rechargeable Flow and Flexible Zn-Air Batteries.

As one of the most promising alternatives for future energy systems, the rechargeable Zn–air battery (ZAB) has attracted extensive attention due to its extraordinarily high theoretical specific energy density. However, several obstacles restrict its practical application. One challenge is the sluggish kinetics of oxygen-reduction reaction (ORR) and oxygen-evolution reaction (OER) in the discharging and charging processes of ZABs. In addition, when using unifunctional ORR or OER electrocatalysts as air electrodes, like noble metal catalysts (Pt/C or Ru/IrO2), there are the disadvantages of high cost and poor stability. Therefore, rational design of non-noble metal bifunctional ORR/OER electrocatalysts with high activity and stability is essential for the development of ZABs. In this review, we discuss the latest developments of non-noble metal bifunctional ORR/OER electrocatalysts for ZABs. Firstly, the related reaction mechanisms of ORR and OER are introduced. Then, the latest developments of bifunctional ORR/OER materials for ZABs are discussed in detail from three aspects: (i) MOF-based catalysts, including pristine MOFs and their derivatives; (ii) metal-free-based carbon catalysts, including heteroatom-doped carbon and defective carbon; (iii) metal-based catalysts, including metal–nitrogen–carbon materials (such as metals/alloys, single-atom) and metal compound materials. Finally, some challenges and outlooks for the optimal design of bifunctional air electrodes for rechargeable ZABs with high activity and ultra-long lifetime are put forward.

Bifunctional electrocatalysts for Zn–air batteries: recent developments and future perspectives

Rechargeable lithium-iodine (Li-I2) battery is a promising energy storage system because of the high energy and power density. However, the shuttle effects of iodine species and the unstable features of I2 block the practical applications of Li-I2 batteries. Herein, a dual heteroatom doped porous carbon cloth is fabricated as the host material for lithium iodide (LiI). Specifically, the self-standing nitrogen, phosphorus co-doped carbon cloth with high LiI loading exhibits a large specific capacity (221 mAh·g−1 at 1 C), excellent rate capability (95.8% capacity retention at 5 C) and superior long cycling stability (2,000 cycles with a capacity retention of 96%). Electrochemical kinetic analysis confirms the dominant contribution of capacitive effects at high scan rates, which is responsible for the good high-rate performance. The improved electrochemical performance mainly stems from two unique features of nitrogen, phosphorus co-doped porous carbon cloth. Heteroatom doping provides extra active sites for strong adsorption of iodine species while the highly porous structure with large surface area favors the capacitive effects at high rates. This work provides a facile yet efficient approach to regulating both redox reaction and capacitive effects via adjusting surface composition and pore structure of carbon materials for enhanced battery performance.

Nitrogen, phosphorus co-doped carbon cloth as self-standing electrode for lithium-iodine batteries

Rechargeable aqueous zinc-iodine batteries have received extensive attention due to their inherent advantages such as low cost, flame retardancy and safety. To address the safety concern associated with Zn dendrites, tin functional layer is introduced to the Zn surface via a spontaneous galvanic replacement reaction. This provides rapid deposition kinetics, thereby achieving the uniform Zn plating/stripping with a low overpotential (13.9 mV) and good stability for over 900 h. Importantly, the coupling of the advanced Zn anode with iodine in Zn-I<sub>2</sub> battery exhibits a high specific capacity of 196.4 mAh·g<sup>−1</sup> with high capacity retention (90.7%). This work provides a reliable strategy to regulate the reversible redox of zinc for advanced rechargeable batteries. 

A highly reversible dendrite-free Zn anode via spontaneous galvanic replacement reaction for advanced zinc-iodine batteries

Surface modification of SnO2 nanosheets via ultrathin N-doped carbon layers for improving CO2 electrocatalytic reduction

Thermal Sugar Bubbling Preparation of N‐Doped Porous Carbon for High‐Performance Solid‐State Zn‐Air Batteries

Aqueous Zn batteries (AZBs) have attracted extensive attention due to good safety, cost-effectiveness, and environmental benignity. However, the sluggish kinetics of divalent zinc ion and the growth of Zn dendrites severely deteriorate the cycling stability and specific capacity. The authors demonstrate modulation of the interfacial redox process of zinc via the dynamic coordination chemistry of phytic acid with zinc ions. The experimental results and theoretical calculation reveal that the in-situ formation of such inorganic-organic films as a dynamic solid-electrolyte interlayer is efficient to buffer the zinc ion transfer via the energy favorable coordinated hopping mechanism for the reversible zinc redox reactions. Especially, along the interfacial coating layer with porous channel structure is able to regulate the solvation structure of zinc ions along the dynamic coordination of the phytic acid skeleton, efficiently inhibiting the surface corrosion of zinc and dendrite growth. Therefore, the resultant Zn anode achieves low voltage hysteresis and long cycle life at rigorous charge and discharge circulation for fabricating highly robust rechargeable batteries. Such an advanced strategy for modulating ion transport demonstrates a highly promising approach to addressing the basic challenges for zinc-based rechargeable batteries, which can potentially be extended to other aqueous batteries.

Song Chen

Papers

Nitrogen, phosphorus co-doped carbon cloth as self-standing electrode for lithium-iodine batteries

A highly reversible dendrite-free Zn anode via spontaneous galvanic replacement reaction for advanced zinc-iodine batteries

Surface modification of SnO2 nanosheets via ultrathin N-doped carbon layers for improving CO2 electrocatalytic reduction

Thermal Sugar Bubbling Preparation of N‐Doped Porous Carbon for High‐Performance Solid‐State Zn‐Air Batteries

Interface Coordination Stabilizing Reversible Redox of Zinc for High-Performance Zinc-Iodine Batteries.