能源化学最新文献

The balance between cationic redox and oxygen redox in layer-structured cathode materials is an important issue for sodium batteries to obtain high energy density and considerable cycle stability. Oxygen redox can contribute extra capacity to increase energy density, but results in lattice instability and capacity fading caused by lattice oxygen gliding and oxygen release. In this work, reversible Mn²⁺/Mn⁴⁺ redox is realized in a P3-Na_0.65Li_0.2Co_0.05Mn_0.75O₂ cathode material with high specific capacity and structure stability via Co substitution. The contribution of oxygen redox is suppressed significantly by reversible Mn²⁺/Mn⁴⁺ redox without sacrificing capacity, thus reducing lattice oxygen release and improving the structure stability. Synchrotron X-ray techniques reveal that P3 phase is well maintained in a wide voltage window of 1.5–4.5 V vs. Na⁺/Na even at 10 C and after long-term cycling. It is disclosed that charge compensation from Co/Mn-ions contributes to the voltage region below 4.2 V and O-ions contribute to the whole voltage range. The synergistic contributions of Mn²⁺/Mn⁴⁺, Co²⁺/Co³⁺, and O²⁻/(O_n)²⁻ redox in P3-Na_0.65Li_0.2Co_0.05Mn_0.75O₂ lead to a high reversible capacity of 215.0 mA h g⁻¹ at 0.1 C with considerable cycle stability. The strategy opens up new opportunities for the design of high capacity cathode materials for rechargeable batteries.

BiVO₄ (BVO) is a promising material as the photoanode for use in photoelectrochemical applications. However, the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical performance. To address this, various modifications have been attempted, including the use of ferroelectric materials. Ferroelectric materials can form a permanent polarization within the layer, enhancing the separation and transport of photo-excited electron-hole pairs. In this study, we propose a novel approach by depositing an epitaxial BiFeO₃ (BFO) thin film underneath the BVO thin film (BVO/BFO) to harness the ferroelectric property of BFO. The self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge recombination. As a result, the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density (0.65 mA cm⁻²) at 1.23 V_RHE under the illumination compared to the bare BVO photoanodes (0.18 mA cm⁻²), which is consistent with the increase of the applied bias photon-to-current conversion efficiencies (ABPE) and the result of electrochemical impedance spectroscopy (EIS) analysis. These results can be attributed to the self-polarization exhibited by the inserted BFO thin film, which promoted the charge separation and transfer efficiency of the BVO photoanodes.

Smart wearable devices are regarded to be the next prevailing technology product after smartphones and smart homes, and thus there has recently been rapid development in flexible electronic energy storage devices. Among them, flexible solid-state zinc-air batteries have received widespread attention because of their high energy density, good safety, and stability. Efficient bifunctional oxygen electrocatalysts are the primary consideration in the development of flexible solid-state zinc-air batteries, and self-supported air cathodes are strong candidates because of their advantages including simplified fabrication process, reduced interfacial resistance, accelerated electron transfer, and good flexibility. This review outlines the research progress in the design and construction of nanoarray bifunctional oxygen electrocatalysts. Starting from the configuration and basic principles of zinc-air batteries and the strategies for the design of bifunctional oxygen electrocatalysts, a detailed discussion of self-supported air cathodes on carbon and metal substrates and their uses in flexible zinc-air batteries will follow. Finally, the challenges and opportunities in the development of flexible zinc-air batteries will be discussed.

Rechargeable magnesium batteries (RMBs) hold promise for offering higher volumetric energy density and safety features, attracting increasing research interest as the next post lithium-ion batteries. Developing high performance cathode material by inducing multi-electron reaction process as well as maintaining structural stability is the key to the development and application of RMBs. Herein, multi-electron reaction occurred in VS₄ by simple W doping strategy. W doping induces valence of partial V as V²⁺ and V³⁺ in VS₄ structure, and then stimulates electrochemical reaction involving multi-electrons in 0.5% W-V-S. The flower-like microsphere morphology as well as rich S vacancies is also modulated by W doping to neutralize structure change in such multi-electron reaction process. The fabricated 0.5% W-V-S delivers higher specific capacity (149.3 mA h g⁻¹ at 50 mA g⁻¹, which is 1.6 times higher than that of VS₄), superior rate capability (76 mA h g⁻¹ at 1000 mA g⁻¹), and stable cycling performance (1500 cycles with capacity retention ratio of 93.8%). Besides that, pesudocapaticance-like contribution analysis as well as galvanostatic intermittent titration technique (GITT) further confirms the enhanced Mg²⁺ storage kinetics during such multi-electron involved electrochemical reaction process. Such discovery provides new insights into the designing of multi-electron reaction process in cathode as well as neutralizing structural change during such reaction for realizing superior electrochemical performance in energy storage devices.

Focusing on the low open circuit voltage (V_OC) and fill factor (FF) in flexible Cu₂ZnSn(S,Se)₄ (CZTSSe) solar cells, indium (In) ions are introduced into the CZTSSe absorbers near Mo foils to modify the back interface and passivate deep level defects in CZTSSe bulk concurrently for improving the performance of flexible device. The results show that In doping effectively inhibits the formation of secondary phase (Cu(S,Se)₂) and V_Sn defects. Further studies demonstrate that the barrier height at the back interface is decreased and the deep level defects (Cu_Sn defects) in CZTSSe bulk are passivated. Moreover, the carrier concentration is increased and the V_OC deficit (V_OC,def) is decreased significantly due to In doping. Finally, the flexible CZTSSe solar cell with 10.01% power conversion efficiency (PCE) has been obtained. The synergistic strategy of interface modification and bulk defects passivation through In incorporation provides a new thought for the fabrication of efficient flexible kesterite-based solar cells.

There have been reports about Fe ions boosting oxygen evolution reaction (OER) activity of Ni-based catalysts in alkaline conditions, while the origin and reason for the enhancement remains elusive. Herein, we attempt to identify the activity improvement and discover that Ni sites act as a host to attract Fe(III) to form Fe(Ni)(III) binary centres, which serve as the dynamic sites to promote OER activity and stability by cyclical formation of intermediates (Fe(III) → Fe(Ni)(III) → Fe(Ni)–OH → Fe(Ni)–O → Fe(Ni)OOH → Fe(III)) at the electrode/electrolyte interface to emit O₂. Additionally, some ions (Co(II), Ni(II), and Cr(III)) can also be the active sites to catalyze the OER process on a variety of electrodes. The Fe(III)-catalyzed overall water-splitting electrolyzer comprising bare Ni foam as the anode and Pt/Ni-Mo as the cathode demonstrates robust stability for 1600 h at 1000 mA cm⁻²@∼1.75 V. The results provide insights into the ion-catalyzed effects boosting OER performance.

The development of a durable metallic coating on diverse substrates is both intriguing and challenging, particularly in the research of metal-conductive materials for applications such as batteries, soft electronics, and beyond. Herein, by learning from the pencil-writing process, a facile solid-ink rubbing technology (SIR-tech) is invented to address the above challenge. The solid-ink is exampled by rational combination of liquid metal and graphite particles. By harnessing the synergistic effects between rubbing and adhesion, controllable metallic skin is successfully formed onto metals, woods, ceramics, and plastics without limitation in size and shape. Moreover, outperforming pure liquid-metal coating, the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing. The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well. For applications, the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils. Meanwhile, advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from −196 to 120 °C. This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.

As a new generation electrode materials for energy storage, perovskites have attracted wide attention because of their unique crystal structure, reversible active sites, rich oxygen vacancies, and good stability. In this review, the design and engineering progress of perovskite materials for supercapacitors (SCs) in recent years is summarized. Specifically, the review will focus on four types of perovskites, perovskite oxides, halide perovskites, fluoride perovskites, and multi-perovskites, within the context of their intrinsic structure and corresponding electrochemical performance. A series of experimental variables, such as synthesis, crystal structure, and electrochemical reaction mechanism, will be carefully analyzed by combining various advanced characterization techniques and theoretical calculations. The applications of these materials as electrodes are then featured for various SCs. Finally, we look forward to the prospects and challenges of perovskite-type SCs electrodes, as well as the future research direction.

Advancing high-voltage stability of layered sodium-ion oxides represents a pivotal avenue for their progress in energy storage applications. Despite this, a comprehensive understanding of the mechanisms underpinning their structural deterioration at elevated voltages remains insufficiently explored. In this study, we unveil a layer delamination phenomenon of Na_0.67Ni_0.3Mn_0.7O₂ (NNM) within the 2.0–4.3 V voltage, attributed to considerable volumetric fluctuations along the c-axis and lattice oxygen reactions induced by the simultaneous Ni³⁺/Ni⁴⁺ and anion redox reactions. By introducing Mg doping to diminished Ni–O antibonding, the anion oxidation-reduction reactions are effectively mitigated, and the structural integrity of the P2 phase remains firmly intact, safeguarding active sites and precluding the formation of novel interfaces. The Na_0.67Mg_0.05Ni_0.25Mn_0.7O₂ (NMNM-5) exhibits a specific capacity of 100.7 mA h g⁻¹, signifying an 83% improvement compared to the NNM material within the voltage of 2.0–4.3 V. This investigation underscores the intricate interplay between high-voltage stability and structural degradation mechanisms in layered sodium-ion oxides.

Polymer-based composite electrolytes composed of three-dimensional Li_6.4La₃Zr₂Al_0.2O₁₂ (3D-LLZAO) have attracted increasing attention due to their continuous ion conduction and satisfactory mechanical properties. However, the organic/inorganic interface is incompatible, resulting in slow lithium-ion transport at the interface. Therefore, the compatibility of organic/inorganic interface is an urgent problem to be solved. Inspired by the concept of “gecko eaves”, polymer-based composite solid electrolytes with dense interface structures were designed. The bridging of organic/inorganic interfaces was established by introducing silane coupling agent (3-chloropropyl)trimethoxysilane (CTMS) into the PEO-3D-LLZAO (PL) electrolyte. The in-situ coupling reaction improves the interface affinity, strengthens the organic/inorganic interaction, reduces the interface resistance, and thus achieves an efficient interface ion transport network. The prepared PEO-3D-LLZAO-CTMS (PLC) electrolyte exhibits enhanced ionic conductivity of 6.04 × 10⁻⁴ S cm⁻¹ and high ion migration number (0.61) at 60 °C and broadens the electrochemical window (5.1 V). At the same time, the PLC electrolyte has good thermal stability and high mechanical properties. Moreover, the LiFePO₄|PLC|Li battery has excellent rate performance and cycling stability with a capacity decay rate of 2.2% after 100 cycles at 60 °C and 0.1 C. These advantages of PLC membranes indicate that this design approach is indeed practical, and the in-situ coupling method provides a new approach to address interface compatibility issues.