能源化学最新文献

Owning various crystal structures and high theoretical capacity, metal tellurides are emerging as promising electrode materials for high-performance metal-ion batteries (MBs). Since metal telluride-based MBs are quite new, fundamental issues raise regarding the energy storage mechanism and other aspects affecting electrochemical performance. Severe volume expansion, low intrinsic conductivity and slow ion diffusion kinetics jeopardize the performance of metal tellurides, so that rational design and engineering are crucial to circumvent these disadvantages. Herein, this review provides an in-depth discussion of recent investigations and progresses of metal tellurides, beginning with a critical discussion on the energy storage mechanisms of metal tellurides in various MBs. In the following, recent design and engineering strategies of metal tellurides, including morphology engineering, compositing, defect engineering and heterostructure construction, for high-performance MBs are summarized. The primary focus is to present a comprehensive understanding of the structural evolution based on the mechanism and corresponding effects of dimension control, composition, electron configuration and structural complexity on the electrochemical performance. In closing, outlooks and prospects for future development of metal tellurides are proposed. This work also highlights the promising directions of design and engineering strategies of metal tellurides with high performance and low cost.

Lithium sulfur (Li-S) battery is a kind of burgeoning energy storage system with high energy density. However, the electrolyte-soluble intermediate lithium polysulfides (LiPSs) undergo notorious shuttle effect, which seriously hinders the commercialization of Li-S batteries. Herein, a unique VSe₂/V₂C heterostructure with local built-in electric field was rationally engineered from V₂C parent via a facile thermal selenization process. It exquisitely synergizes the strong affinity of V₂C with the effective electrocatalytic activity of VSe₂. More importantly, the local built-in electric field at the heterointerface can sufficiently promote the electron/ion transport ability and eventually boost the conversion kinetics of sulfur species. The Li-S battery equipped with VSe₂/V₂C-CNTs-PP separator achieved an outstanding initial specific capacity of 1439.1 mA h g⁻¹ with a high capacity retention of 73% after 100 cycles at 0.1 C. More impressively, a wonderful capacity of 571.6 mA h g⁻¹ was effectively maintained after 600 cycles at 2 C with a capacity decay rate of 0.07%. Even under a sulfur loading of 4.8 mg cm⁻², areal capacity still can be up to 5.6 mA h cm⁻². In-situ Raman tests explicitly illustrate the effectiveness of VSe₂/V₂C-CNTs modifier in restricting LiPSs shuttle. Combined with density functional theory calculations, the underlying mechanism of VSe₂/V₂C heterostructure for remedying LiPSs shuttling and conversion kinetics was deciphered. The strategy of constructing VSe₂/V₂C heterocatalyst in this work proposes a universal protocol to design metal selenide-based separator modifier for Li-S battery. Besides, it opens an efficient avenue for the separator engineering of Li-S batteries.

Exploring effective iridium (Ir)-based electrocatalysts with stable iridium centers is highly desirable for oxygen evolution reaction (OER). Herein, we regulated the incorporation manner of Ir in Co₃O₄ support to stabilize the Ir sites for effective OER. When anchored on the surface of Co₃O₄ in the form of Ir(OH)₆ species, the created Ir-OH-Co interface leads to a limited stability and poor acidic OER due to Ir leaching. When doped into Co₃O₄ lattice, the analyses of X-ray absorption spectroscopy, in-situ Raman, and OER measurements show that the partially replacement of Co in Co₃O₄ by Ir atoms inclines to cause strong electronic effect and activate lattice oxygen in the presence of Ir-O-Co interface, and simultaneously master the reconstruction effect to mitigate Ir dissolution, realizing the improved OER activity and stability in alkaline and acidic environments. As a result, Ir_lat@Co₃O₄ with Ir loading of 3.67 wt% requires 294 ± 4 mV / 285 ± 3 mV and 326 ± 2 mV to deliver 10 mA cm⁻² in alkaline (0.1 M KOH / 1.0 M KOH) and acidic (0.5 M H₂SO₄) solution, respectively, with good stability.

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.

Transition metal-nitrogen-carbon (M-N-C) as a promising substitute for the conventional noble metal-based catalyst still suffers from low activity and durability for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). To tackle the issue, herein, a new type of sulfur-doped iron-nitrogen-hard carbon (S-Fe-N-HC) nanosheets with high activity and durability in acid media were developed by using a newly synthesized precursor of amide-based polymer with Fe ions based on copolymerizing two monomers of 2, 5-thiophene dicarboxylic acid (TDA) as S source and 1, 8-diaminonaphthalene (DAN) as N source via an amination reaction. The as-synthesized S-Fe-N-HC features highly dispersed atomic FeN_x moieties embedded into rich thiophene-S doped hard carbon nanosheets filled with highly twisted graphite-like microcrystals, which is distinguished from the majority of M-N-C with soft or graphitic carbon structures. These unique characteristics endow S-Fe-N-HC with high ORR activity and outstanding durability in 0.5 M H₂SO₄. Its initial half-wave potential is 0.80 V and the corresponding loss is only 21 mV after 30,000 cycles. Meanwhile, its practical PEMFC performance is a maximum power output of 628.0 mW cm⁻² and a slight power density loss is 83.0 mW cm⁻² after 200-cycle practical operation. Additionally, theoretical calculation shows that the activity of FeN_x moieties on ORR can be further enhanced by sulfur doping at meta-site near FeN₄C. These results evidently demonstrate that the dual effect of hard carbon substrate and S doping derived from the precursor platform of amid-polymers can effectively enhance the activity and durability of Fe-N-C catalysts, providing a new guidance for developing advanced M-N-C catalysts for ORR.

The anti-freezing strategy of hydrogels and their self-healing structure are often contradictory, it is vital to break through the molecular structure to design and construct hydrogels with intrinsic anti-freezing/self-healing for meeting the rapid development of flexible and wearable devices in diverse service conditions. Herein, we design a new hydrogel electrolyte (AF/SH-Hydrogel) with intrinsic anti-freezing/self-healing capabilities by introducing ethylene glycol molecules, dynamic chemical bonding (disulfide bond), and supramolecular interaction (multi-hydrogen bond) into the polyacrylamide molecular chain. Thanks to the exceptional freeze resistance (84% capacity retention at −20 °C) and intrinsic self-healing capabilities (95% capacity retention after 5 cutting/self-healing cycles), the obtained AF/SH-Hydrogel makes the zinc||manganese dioxide cell an economically feasible battery for the state-of-the-art applications. The Zn||AF/SH-Hydrogel||MnO₂ device offers a near-theoretical specific capacity of 285 mA h g⁻¹ at 0.1 A g⁻¹ (Coulombic efficiency ≈100%), as well as good self-healing capability and mechanical flexibility in an ice bath. This work provides insight that can be utilized to develop multifunctional hydrogel electrolytes for application in next generation of self-healable and freeze-resistance smart aqueous energy storage devices.

Exploration of advanced gel polymer electrolytes (GPEs) represents a viable strategy for mitigating dendritic lithium (Li) growth, which is crucial in ensuring the safe operation of high energy density Li metal batteries (LMBs). Despite this, the application of GPEs is still hindered by inadequate ionic conductivity, low Li⁺ transference number, and subpar physicochemical properties. Herein, TiO_2−x nanofibers (NF) with oxygen vacancy defects were synthesized by a one-step process as inorganic fillers to enhance the thermal/mechanical/ionic-transportation performances of composite GPEs. Various characterizations and theoretical calculations reveal that the oxygen vacancies on the surface of TiO_2−x NF accelerate the dissociation of LiPF₆, promote the rapid transfer of free Li⁺, and influence the formation of LiF-enriched solid electrolyte interphase. Consequently, the composite GPEs demonstrate enhanced ionic conductivity (1.90 mS cm⁻¹ at room temperature), higher lithium-ion transference number (0.70), wider electrochemical stability window (5.50 V), superior mechanical strength, excellent thermal stability (210 °C), and improved compatibility with lithium, resulting in superior cycling stability and rate performance in both Li||Li, Li||LiFePO₄, and Li||LiNi_0.8Co_0.1Mn_0.1O₂ cells. Overall, the synergistic influence of nanofiber morphology and enriched oxygen vacancy structure of fillers on electrochemical properties of composite GPEs is comprehensively investigated, thus, it is anticipated to shed new light on designing high-performance GPEs LMBs.

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.

The unparalleled energy density has granted lithium-sulfur batteries (LSBs) with attractive usages. Unfortunately, LSBs still face some unsurpassed challenges in industrialization, with polysulfides shuttling, dendrite growth and thermal hazard as the major problems triggering the cycling instability and low safety. With the merit of convenience, the method of designing functional separator has been adapted. Concretely, the carbon aerogel confined with CoS₂ (CoS₂-NCA) is constructed and coated on Celgard separator surface, acquiring CoS₂-NCA modified separator (CoS₂-NCA@C), which holds the promoted electrolyte affinity and flame retardance. As revealed, CoS₂-NCA@C cell gives a high discharge capacity 1536.9 mAh/g at 1st cycle, much higher than that of Celgard cell (987.1 mAh/g). Moreover, the thermal runaway triggering time is dramatically prolonged by 777.4 min, corroborating the promoted thermal safety of cell. Noticeably, the higher coulombic efficiency stability and lower overpotential jointly confirm the efficacy of CoS₂-NCA@C in suppressing the lithium dendrite growth. Overall, this work can provide useful inspirations for designing functional separator, coping with the vexing issues of LSBs.

CsPbI₂Br perovskite solar cells (PSCs) have drawn tremendous attention due to their suitable bandgap, excellent photothermal stability, and great potential as an ideal candidate for top cells in tandem solar cells. However, the abundant defects at the buried interface and perovskite layer induce severe charge recombination, resulting in the open-circuit voltage (V_oc) output and stability much lower than anticipated. Herein, a novel buried interface management strategy is developed to regulate interfacial carrier dynamics and CsPbI₂Br defects by introducing ammonium tetrafluoroborate (NH₄BF₄), thereby resulting in both high CsPbI₂Br crystallization and minimized interfacial energy losses. Specifically, NH₄⁺ ions could preferentially heal hydroxyl groups on the SnO₂ surface and balance energy level alignment between SnO₂ and CsPbI₂Br, enhancing charge transport efficiency, while BF₄⁻ anions as a quasi-halogen regulate crystal growth of CsPbI₂Br, thus reducing perovskite defects. Additionally, it is proved that eliminating hydroxyl groups at the buried interface enhances the iodide migration activation energy of CsPbI₂Br for strengthening the phase stability. As a result, the optimized CsPbI₂Br PSCs realize a remarkable efficiency of 17.09% and an ultrahigh V_oc output of 1.43 V, which is one of the highest values for CsPbI₂Br PSCs.