Search

The doping of non-lithium cations has a very significant effect on the electrochemical performance of inorganic solid electrolytes. In this work, the effect of non-lithium cations on the ionic conductivity of LISICON-type solid electrolytes at different lithium-ion concentrations is investigated based on first principles calculations. The results show that the doping of non-lithium cations has different effects on Li+ diffusion at different lithium-ion concentrations. This might be due to the fact that the doping of non-lithium cations at different lithium-ion concentrations results in different changes in the energy landscape of lithium ions. Therefore, we propose that large non-lithium cation doping can increase lithium-ion conductivity at low lithium-ion concentrations while the doping of non-lithium cations with a small radius can improve the lithium-ion conductivity at high lithium-ion concentrations. Besides, all these solid electrolytes are proved to be poor electronic conductors with a wide bandgap. Finally, from the thermodynamic point of view, these solid electrolytes show good thermal stability and match well with LiNiO2. These superior properties indicate that these materials are very promising solid electrolytes for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The pore structure and atomic arrangement of nanosized carbon are accurately regulated by the smart combination of in situ graphitization and self-activation effect. Benefiting from the scalpel-like regulation of the ratio between the catalyst and activator, ordered–disordered hybrid graphitic carbon anodes with abundant pores are achieved. Especially, the GCFs-3 sample delivers a plateau capacity of 285.3 mA h g−1 even at 0.1 A g−1 in Li-half cells, and possesses fast charge–discharge capability at high rates. Further, the self-activated mesoporous carbon with specific surface area as high as 1522.2 m2 g−1 exhibits a high specific capacity of 56.6 mA h g−1 (vs. 45.1 mA h g−1 of commercial activated carbon) at 0.05 A g−1. The superior-rate graphitic carbon negative electrode and high-specific-capacity mesoporous activated carbon positive electrode satisfy perfectly the demand for high-energy-density and superior-power-output dual-carbon lithium-ion capacitors (LICs). When assembled into LICs, high energy density (86.4 W h kg−1, 62.2 W kg−1), excellent power density (19.8 kW kg−1, 60.3 W h kg−1) and long-term cycling stability (98.1% after 20 000 times at 5.0 A g−1) are achieved, outperforming the state-of-the-art LIC configurations. This tactic opens a new window for the design of electrode materials via utilizing the synergistic effect between the catalyst and activator to adjust the microstructures. [ABSTRACT FROM AUTHOR]

Infinite volume expansion and high reactivity severely hinder the commercial applications of lithium metal batteries. Moreover, the short circuit caused by Li dendrites is fatal for the long-term performance of lithium metal batteries and may cause safety problems. Herein, lithiophilic silver/lithium (Ag/Li) composite anodes are synthesized via a spontaneous displacement reaction between silver nitrate and Li foil at room temperature, which can settle the above challenges by regulating Li nucleation and homogenizing Li-ion flux. Benefiting from the lithiophilic design, Li ion realizes zero nucleation overpotential on the as-obtained Ag/Li anodes with abundant spherical silver nanoparticles. Additionally, the by-product, lithium nitrate, acts as an electrolyte additive, which further ensures uniform Li deposition. Consequently, Ag/Li symmetric cells demonstrate ultralong lifespan with repeated plating/stripping for 1000 cycles at the current densities of 1 mA cm−2 and 5 mA cm−2, with negligible voltage fluctuations. Furthermore, the full-cell devices, paired with LiFePO4, also exhibit excellent electrochemical performance. The facile and effective strategy provides a promising prospect for commercial applications of lithium metal batteries. [ABSTRACT FROM AUTHOR]

Novel triclinic LiV(PO4)0.9F1.3, characterized through its crystal lattice expansion, ultrafine primary particle size and uniform carbon coating, was designed and fabricated through regulating the PO4/F ratio. It exhibited excellent electrochemical performance, maintaining 105 mA h g−1 at 50C and 92.9% capacity retention after 500 cycles at 10C due to its superior structural stability, greater charge transfer properties, enhanced electronic conductivity and fast Li+ diffusion kinetics. [ABSTRACT FROM AUTHOR]

By reducing the gap between lithium-ion batteries (LIBs) and supercapacitors (SCs) effectively, lithium-ion capacitors (LICs) have attracted tremendous attention among various electrochemical energy storage systems because they exhibit a high energy density (inherited from the LIBs), a high power output, long lifespan (owing to the SCs) and favorable chemical stability. Carbonaceous electrode materials play significant roles in high performance dual-carbon LICs whether positive or negative. Here, the working mechanism, cell design principle and recent progress in carbon-based electrode materials for dual-carbon LICs are illustrated. Then, the commercialization of LICs is discussed briefly. Finally, some suggestions for the future developments associated with dual-carbon LICs are proposed. [ABSTRACT FROM AUTHOR]

Functional nanostructured materials have attracted great attention over the past several decades owing to their unique physical and chemical properties, while their applications have been proven to be advantageous not only in fundamental scientific areas, but also in many technological fields. Spray pyrolysis (SP), which is particularly facile, effective, highly scalable and suitable for on-line continuous production, offers significant potential for the rational design and synthesis of various functional nanostructured materials with tailorable composition and morphology. In this review, we summarize the recent progress in various functional nanostructured materials synthesized by SP and their potential applications in energy storage and conversion. After a brief introduction to the equipment, components, and working principles of the SP technique, we thoroughly describe the guidelines and strategies for designing particles with controlled morphology, composition, and interior architecture, including hollow structures, dense spheres, yolk–shell structures, core–shell structures, nanoplates, nanorods, nanowires, thin films, and various nanocomposites. Thereafter, we demonstrate their suitability for a wide range of energy storage and conversion applications, including electrode materials for rechargeable batteries, supercapacitors, highly active catalysts for hydrogen production, carbon dioxide reduction and fuel cells, and photoelectric materials for solar cells. Finally, the potential advantages and challenges of SP for the preparation of nanostructured materials are particularly emphasized and discussed, and several perspectives on future research and development directions of SP are highlighted. We expect that this continuous, one-pot, and controllable synthetic technology can serve as a reference for preparing various advanced functional materials for broader applications. [ABSTRACT FROM AUTHOR]

Tin oxides as some of the potential candidates for commercial graphite anodes suffer from serious drawbacks such as poor electronic conductivity and large volume variation during cycling. Dispersing nanostructured SnOx into a carbon matrix may be an effective strategy to solve these problems. In this work, a novel dried plum-like yolk–shell SnOx/C architecture with high specific surface area and superior structural stability is constructed by an extremely facile and scalable spray pyrolysis method in ten seconds. The SnOx nanodots (＜10 nm) are uniformly embedded into the in situ generated carbon matrix. Polyvinylpyrrolidone is introduced here as a multifunctional agent to generate the dried plum-like yolk–shell morphology as well as to form the carbon matrix. The formation mechanism of such a unique morphology is discussed and revealed with in-depth comparison. As an anode for lithium ion batteries, the characteristic SnOx/C yolk–shell microspheres exhibit a high reversible capacity of 1142 mA h g−1 at 0.2 A g−1, good rate capability of 509 mA h g−1 at 5 A g−1, and excellent cycling performance of ∼100% capacity retention in 600 cycles. This work provides an ultra-simple route for large scale production of yolk–shell nanomaterials for energy-related as well as other applications. [ABSTRACT FROM AUTHOR]

A facile and large-scale fluidized bed reaction route was introduced for the first time to prepare crystalline embedded amorphous silicon nanoparticles with an average size of 50 nm as anode materials for lithium-ion batteries. By increasing the operating potential to control the electrochemically active degree, the resulting sample showed excellent cycle stability with a high capacity retention of 94.7% after 200 cycles at 1 A g−1 in the voltage range of 0.12–2.00 V. [ABSTRACT FROM AUTHOR]

Graphitic carbon (GC) derived from sisal fibers is prepared through pre-carbonization and catalytic graphitization at low temperature (＜1200 °C). The plateau capacity is regulated by the ordered degree of GC. The as-prepared GC1100 at 1100 °C possesses a high plateau capacity of 243 mA h g−1 below 0.2 V representing 68% of the total reversible capacity of 354 mA h g−1 at 0.05 A g−1, high rate capability (222 mA h g−1 at 1 A g−1) and excellent cycling stability. The superior electrochemical performance is ascribed to the coexistence of graphitic structure and amorphous structure. The graphitic structure contributes to high plateau capacity and electrical conductivity, and the amorphous structure supplies a more convenient pathway for Li+ ions and protects the graphitic structure from the etching of the electrolyte. Additionally, a lithium ion capacitor (LIC) is assembled with sisal fiber activated carbon (SFAC-2) as the positive electrode and GC1100 as the negative electrode. The LIC displays high energy densities of 104 and 32 W h kg−1 obtained at 143 and 6628 W kg−1, respectively, and outstanding cycling stability with the energy density retention of 94.7% at 0.5 A g−1 and 96.5% at 1 A g−1 after 3000 cycles. [ABSTRACT FROM AUTHOR]

Novel hierarchical nickel–cobalt oxide microspheres with a multishell yolk–shell structure have been accurately synthesized via a facile and scalable method. The multishell yolk–shell powder shows a significantly improved electrochemical performance in terms of high reversible capacity, good rate capability and excellent cycling performance. [ABSTRACT FROM AUTHOR]

Herein, we introduced a new design concept for fabricating nickel-foam-supported metal oxide microsphere as an anode for lithium-ion batteries (LIBs). Porous metal oxide microspheres were synthesized via spray pyrolysis. A piece of nickel foam was placed at the exit of the reactor to filter the off-gas and thus to obtain the metal oxide powders. A thin layer of porous metal oxide microspheres was uniformly deposited on the nickel foam within ∼20 minutes. The nickel-foam-supported metal oxide microsphere was directly used as a binder-free anode for the LIBs. The electrochemical properties of the nickel-foam-supported Co3O4 microsphere (prepared as the first target material) were investigated. The as-prepared anode retains a reversible capacity of 1085 mA h g−1 after 180 cycles. More strikingly, it manifests excellent rate performance with a capacity of 555 mA h g−1 even at 3200 mA g−1. Compared to the available methods that are typically time-consuming and complicated, this smart strategy described herein is efficient and simple. It is strongly envisioned that this elegant design concept holds great potential for the efficient synthesis of other nickel-foam-supported metal oxides as electrodes for LIBs or supercapacitors. [ABSTRACT FROM AUTHOR]

To improve the cycle performance of LiMn2O4 at elevated temperature, a graphite layer is introduced to directly cover the surface of a commercial LiMn2O4-based electrode via room-temperature DC magnetron sputtering. The as-modified cathodes display improved capacity retention as compared to the bare LiMn2O4 cathode (BLMO) at 55 °C. When sputtering graphite for 30 min, the sample shows the best cycling performance at 55 °C, maintaining 96.2% capacity retention after 200 cycles. Reasons with respect to the graphite layer for improving the elevated-temperature performance of LiMn2O4 are systematically investigated via the methods of cyclic voltammetry, electrochemical impedance spectroscopy, X-ray photoelectron spectrometry, scanning and transmission electron microscopy, X-ray diffraction and inductively coupled plasma-atomic emission spectrometry. The results demonstrate that the graphite coated LiMn2O4 cathode has much less increased electrode polarization and electrochemical impedance than BLMO during the elevated-temperature cycling process. Furthermore, the graphite layer is able to alleviate the severe dissolution of manganese ions into the electrolyte and mitigate the morphological and structural degradation of LiMn2O4 during cycling. A model for the electrochemical kinetics process is also suggested for explaining the roles of the graphite layer in suppressing the Mn dissolution. [ABSTRACT FROM AUTHOR]

Novel three-dimensional (3D) hierarchical NiSi[sub x]/Co[sub 3]O[sub 4] core-shell nanowire arrays composed of NiSi[sub x] nanowire cores and branched Co[sub 3]O[sub 4] nanosheet shells have been successfully synthesized by combining chemical vapor deposition and a simple but effective chemical bath deposition process followed by a calcination process. The resulting hierarchical NiSi[sub x]/Co[sub 3]O[sub 4] core-shell nanowire arrays directly serve as binder- and conductive-agent-free electrodes for lithium ion batteries, which demonstrate remarkably improved electrochemical performances with excellent capacity retention and high rate capability on cycling. They can maintain a stable reversible capacity of 1279 mA h g[sup -1] after 100 cycles at a current density of 400 mA g[sup -1] and a capacity higher than 340 mA h g[sup -1] even at a current density as high as 8 A g[sup -1]. Such superior electrochemical performance of the electrodes made by directly growing electro-active highly porous Co[sub 3]O[sub 4] on a nanostructured NiSi[sub x] conductive current collector makes them very promising for applications in high-performance lithium ion batteries. [ABSTRACT FROM AUTHOR]

Large-scale vertically aligned single crystalline CuO nanowires grown directly on nickel foam have been successfully fabricated by facile thermal oxidation of e-beam evaporated Cu thin films in static air. A growth mechanism based on stress-driven grain-boundary diffusion associated with surface diffusion of Cu atoms/ions is proposed to explain the formation of CuO nanowires on nickel foam. The resulting CuO nanowires are directly used as binder- and conductive-agent-free electrodes for lithium ion batteries and demonstrate remarkable electrochemical performance with excellent capacity retention and high rate capability on cycling. It can deliver a stable reversible capacity of 692 mA h g−1 after 50 cycles at a current density of 100 mA g−1 and maintain a high reversible capacity of 445 mA h g−1 over 600 cycles with 95.7% capacity retention even at a high current density of 1000 mA g−1. Such superior electrochemical performance of the electrodes made by directly growing electro-active aligned CuO nanowires on conductive 3D nickel foam makes them have very promising applications in high-performance lithium ion batteries. [ABSTRACT FROM AUTHOR]

Materials with Hexagonal Close Packed (HCP) anionic configuration contain promising lithium-ion conductors. In the HCP anionic structure, when the non-lithium cations occupy the octahedral sites (the important diffusion channels for lithium ions), it is not known whether the nature of fast lithium-ion diffusion will be retained. This work systematically studied the lithium-ion diffusion properties of Li 7 NbO 6 as well as its doped phases on the basis of first-principles calculations. The calculation results show that the lithium-ion conductivity of Li 7 NbO 6 is 0.008 mS cm -1 at room temperature, while the doped phase Li 55 Nb 7 WO 48 with W 6+ doping at the Nb sites possesses a higher lithium-ion conductivity of 0.28 mS cm -1 at room temperature and an activation energy of 0.34 eV. The lithium-ion diffusion mechanism in Li 7 NbO 6 and its doped phase involves concerted migration; besides, they are poor conductors of electrons regardless of whether doping is applied. In addition, W 6+ doping increases the reduction limit of the electrochemical window due to its strong oxidizing property; therefore, an artificial SEI film needs to be applied to reduce interfacial decomposition. The discovery and characterization of the new fast lithium-ion conductor Li 55 Nb 7 WO 48 provide theoretical guidance for the development of new solid electrolytes.

Benefiting from high energy density of ultrahigh-nickel cathode materials and good safety of PEO-based electrolytes, PEO-based ultrahigh-nickel solid-state lithium batteries (SLMBs) are considered to be new-generation energy storage devices. However, the incompatibility of ultrahigh-nickel cathode materials and PEO-based electrolytes is the main challenge due to serious interfacial side reactions. Therefore, the modification of the cathode/electrolyte interface is crucial. Herein, the residual lithium on the surface of LiNi 0.9 Co 0.06 Mn 0.04 O 2 is utilized to construct an interfacial coating layer by reacting with H 3 BO 3 . The in situ formed x Li 2 O-B 2 O 3 coating layer (LBO1-NCM) with high ionic conductivity can be regulated with different crystal structures during the sintering process. Besides, an all-solid-state three-electrode cell is fabricated, which verifies that the x Li 2 O-B 2 O 3 coating can effectively stabilize the interface. Astonishingly, uneven Li anode deposition is observed in SLMBs, which is caused by the breakage of PEO molecular chains due to the strong oxidation of the cathode, while this crosstalk is also suppressed by the x Li 2 O-B 2 O 3 coating layer. Consequently, Li|PEO|LBO1-NCM achieves a substantially improved electrochemical performance, exhibiting 90.5% of capacity retention after 100 cycles for the coin cell and 80.3% of capacity retention after 200 cycles for the pouch cell. Apparently, the targeted modification of interfaces should be paid as much attention as electrolyte optimization in SLMBs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Novel triclinic LiV(PO4)0.9F1.3, characterized through its crystal lattice expansion, ultrafine primary particle size and uniform carbon coating, was designed and fabricated through regulating the PO4/F ratio. It exhibited excellent electrochemical performance, maintaining 105 mA h g-1 at 50C and 92.9% capacity retention after 500 cycles at 10C due to its superior structural stability, greater charge transfer properties, enhanced electronic conductivity and fast Li+ diffusion kinetics.

To improve the cycle performance of LiMn2O4 at elevated temperature, a graphite layer is introduced to directly cover the surface of a commercial LiMn2O4-based electrode via room-temperature DC magnetron sputtering. The as-modified cathodes display improved capacity retention as compared to the bare LiMn2O4 cathode (BLMO) at 55 °C. When sputtering graphite for 30 min, the sample shows the best cycling performance at 55 °C, maintaining 96.2% capacity retention after 200 cycles. Reasons with respect to the graphite layer for improving the elevated-temperature performance of LiMn2O4 are systematically investigated via the methods of cyclic voltammetry, electrochemical impedance spectroscopy, X-ray photoelectron spectrometry, scanning and transmission electron microscopy, X-ray diffraction and inductively coupled plasma-atomic emission spectrometry. The results demonstrate that the graphite coated LiMn2O4 cathode has much less increased electrode polarization and electrochemical impedance than BLMO during the elevated-temperature cycling process. Furthermore, the graphite layer is able to alleviate the severe dissolution of manganese ions into the electrolyte and mitigate the morphological and structural degradation of LiMn2O4 during cycling. A model for the electrochemical kinetics process is also suggested for explaining the roles of the graphite layer in suppressing the Mn dissolution.