Carbon Energy最新文献

Though plenty of research has been conducted to improve the low intrinsic electronic conductivity of NASICON-structured NaTi₂(PO₄)₃ (NTP), realizing sodium-ion batteries with high areal/volumetric capacity still remains a formidable challenge. Herein, a multiscale design from anode material to electrode structure is proposed to obtain a gadolinium-ion-doped and carbon-coated NTP composite electrode (NTP-Gd-C), in which gadolinium ion doping, oxygen vacancy, optimized structure, N-doped carbon coating, and bridging on the three-dimensional network are simultaneously achieved. In the whole electrode, the excellent hierarchical electronic/ionic conductivity and structural stability are simultaneously improved via the synergistic optimization of NTP-Gd-C. As a result, excellent electrochemical performances of NTP-Gd-C electrode with a high areal/volumetric capacity of 1.0 mAh cm⁻²/142.8 mAh cm⁻³, high rate capability (58.3 mAh g⁻¹ at 200 C), long cycle life (ultralow capacity fading of 0.004% per cycle under 10,000 cycles), and wide-temperature electrochemical performances (97.0 mAh g⁻¹ at 2 C under −20°C) are achieved. Moreover, the NTP-Gd-C//Na₃V₂(PO₄)₃/C full cell also delivers an excellent rate capacity of 42.0 mAh g⁻¹ at 200 C and long-term high-capacity retention of 66.2% after 4000 cycles at 20 C.

Synergistic regulation of hierarchical nanostructures and defect engineering is effective in accelerating electron and ion transport for metal oxide electrodes. Herein, carbon nanofiber-supported V₂O₃ with enriched oxygen vacancies (OV-V₂O₃@CNF) was fabricated using the facile electrospinning method, followed by thermal reduction. Differing from the traditional particles embedded within carbon nanofibers or irregularly distributed between carbon nanofibers, the free-standing OV-V₂O₃@CNF allows for V₂O₃ nanosheets to grow vertically on one-dimensional (1D) carbon nanofibers, enabling abundant active sites, shortened ion diffusion pathway, continuous electron transport, and robust structural stability. Meanwhile, density functional theory calculations confirmed that the oxygen vacancies can promote intrinsic electron conductivity and reduce ion diffusion energy barrier. Consequently, the OV-V₂O₃@CNF anode delivers a large reversible capacity of 812 mAh g⁻¹ at 0.1 A g⁻¹, superior rate capability (405 mAh g⁻¹ at 5 A g⁻¹), and long cycle life (378 mAh g⁻¹ at 5 A g⁻¹ after 1000 cycles). Moreover, an all-vanadium full battery (V₂O₅//OV-V₂O₃@CNF) was assembled using an OV-V₂O₃@CNF anode and a V₂O₅ cathode, which outputs a working voltage of 2.5 V with high energy density and power density, suggesting promising practical application. This work offers fresh perspectives on constructing hierarchical 1D nanofiber electrodes by combining defect engineering and electrospinning technology.

High-voltage LiCoO₂ (LCO) can deliver a high capacity and therefore significantly boost the energy density of Li-ion batteries (LIBs). However, its cyclability is still a major problem in terms of commercial applications. Herein, we propose a simple but effective method to greatly improve the high-voltage cyclability of an LCO cathode by constructing a surface LiF modification layer via pyrolysis of the lithiated polyvinylidene fluoride (Li-PVDF) coating under air atmosphere. Benefitting from the good film-forming and strong adhesion ability of Li-PVDF, the thus-obtained LiF layer is uniform, dense, and conformal; therefore, it is capable of acting as a barrier layer to effectively protect the LCO surface from direct exposure to the electrolyte, thus suppressing the interfacial side reactions and surface structure deterioration. Consequently, the high-voltage stability of the LCO electrode is significantly enhanced. Under a high charge cutoff voltage of 4.6 V, the LiF-modified LCO (LiF@LCO) cathode demonstrates a high capacity of 201 mA h g⁻¹ at 0.1 C and a stable cycling performance at 0.5 C with 80.5% capacity retention after 700 cycles, outperforming the vast majority of high-voltage LCO cathodes reported so far.

Front cover image: Enhancing both the number of active sites available and the intrinsic activity of Co-based oxygen evolution reaction (OER) electrocatalysts simultaneously is a desirable goal. In the article number CEY2432, Yuan et al. reported a ZIF-67-derived hierarchical porous cobalt sulfide decorated by Au nanoparticles (denoted as HP-Au@Co_xS_y@ZIF-67) hybrid. The novel three-dimensional hierarchical structure significantly enlarges the three-phase interfaces, accelerating the mass transfer and exposing the active centers. Meanwhile, the electronic structure of Co is modulated by Au through charge transfer, wherein Au and NaBH4 reductant result in an interesting “competition effect” to regulate the relative ratio of Co²⁺/Co³⁺. Consequently, HP-Au@Co_xS_y@ZIF-67 displayed excellent OER performance, enabling efficient water splitting and Zn–air battery application.

Back cover image: Graphite recycling from lithium-ion batteries stands out as a pivotal solution to address the increasing demand for raw materials, in particular for electric vehicles. Olutogun et al. have developed a froth flotation-based process to effectively recycle graphite, as detailed in the article CEY2.483. The study highlights that the structure and morphology of the recycled graphite remain essentially unchanged, and the material shows an excellent cycling stability in newly assembled graphite||NMC₅₃₂ lithium-ion cells, with a capacity retention of about 80% after 1000 cycles, which is comparable to the performance of pristine commercial graphite.

Electrocatalytic water splitting has been identified as a potential candidate for producing clean hydrogen energy with zero carbon emission. However, the sluggish kinetics of oxygen evolution reaction on the anode side of the water-splitting device significantly hinders its practical applications. Generally, the efficiency of oxygen evolution processes depends greatly on the availability of cost-effective catalysts with high activity and selectivity. In recent years, extensive theoretical and experimental studies have demonstrated that cobalt (Co)-based nanomaterials, especially low-dimensional Co-based nanomaterials with a huge specific surface area and abundant unsaturated active sites, have emerged as versatile electrocatalysts for oxygen evolution reactions, and thus, great progress has been made in the rational design and synthesis of Co-based nanomaterials for electrocatalytic oxygen evolution reactions. Considering the remarkable progress in this area, in this timely review, we highlight the most recent developments in Co-based nanomaterials relating to their dimensional control, defect regulation (conductivity), electronic structure regulation, and so forth. Furthermore, a brief conclusion about recent progress achieved in oxygen evolution on Co-based nanomaterials, as well as an outlook on future research challenges, is given.