To improve the utilization of visible light and reduce photogenerated electron/hole recombination, Ti3+ self-doped TiO2/oxygen-doped graphitic carbon nitride (Ti3+-TiO2/O-g-C3N4) heterojunctions were ...prepared via hydrothermal treatment of a mixture of g-C3N4 and titanium oxohydride sol obtained from the reaction of TiH2 with H2O2. In this way, exfoliated O-g-C3N4 and Ti3+-TiO2 nanoparticles were obtained. Simultaneously, strong bonding was formed between Ti3+-TiO2 nanoparticles and exfoliated O-g-C3N4 during the hydrothermal process. Charge transfer and recombination processes were characterized by transient photocurrent responses, electrochemical impedance test, and photoluminescence spectroscopy. The photocatalytic performances were investigated through rhodamine B degradation test under an irradiation source based on 30 W cold visible-light-emitting diode. The highest visible-light photoelectrochemical and photocatalytic activities were observed from the heterojunction with 1:2 mass ratio of Ti3+-TiO2 to O-g-C3N4. The photodegradation reaction rate constant based on this heterojuction is 0.0356 min–1, which is 3.87 and 4.56 times higher than those of pristine Ti3+-TiO2 and pure g-C3N4, respectively. The remarkably high photoelectrochemical and photocatalytic performances of the heterojunctions are mainly attributed to the synergetic effect of efficient photogenerated electron–hole separation, decreased electron transfer resistance from interfacial chemical hydroxy residue bonds, and oxidizing groups originating from Ti3+-TiO2 and O-g-C3N4.
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IJS, KILJ, NUK, PNG, UL, UM
The currently commercialized lithium‐ion batteries have allowed for the creation of practical electric vehicles, simultaneously satisfying many stringent milestones in energy density, lifetime, ...safety, power, and cost requirements of the electric vehicle economy. The next wave of consumer electric vehicles is just around the corner. Although widely adopted in the vehicle market, lithium‐ion batteries still require further development to sustain their dominating roles among competitors. In this review, the authors survey the state‐of‐the‐art active electrode materials and cell chemistries for automotive batteries. The performance, production, and cost are included. The advances and challenges in the lithium‐ion battery economy from the material design to the cell and the battery packs fitting the rapid developing automotive market are discussed in detail. Also, new technologies of promising battery chemistries are comprehensively evaluated for their potential to satisfy the targets of future electric vehicles.
A detailed discussion on the various aspects of the lithium‐ion battery industry is presented. From raw material cost breakdowns to government mandates, to a brief discussion on the future of Li‐based energy storage systems, the authors draw a clear picture of the high level aspects of this industry.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Composites incorporating metal nanoparticles (MNPs) within metal-organic frameworks (MOFs) have broad applications in many fields. However, the controlled spatial distribution of the MNPs within MOFs ...remains a challenge for addressing key issues in catalysis, for example, the efficiency of catalysts due to the limitation of molecular diffusion within MOF channels. Here we report a facile strategy that enables MNPs to be encapsulated into MOFs with controllable spatial localization by using metal oxide both as support to load MNPs and as a sacrificial template to grow MOFs. This strategy is versatile to a variety of MNPs and MOF crystals. By localizing the encapsulated MNPs closer to the surface of MOFs, the resultant MNPs@MOF composites not only exhibit effective selectivity derived from MOF cavities, but also enhanced catalytic activity due to the spatial regulation of MNPs as close as possible to the MOF surface.
Three-dimensional nanoporous carbon frameworks encapsulated Sn nanoparticles (Sn@3D-NPC) are developed by a facile method as an improved lithium ion battery anode. The Sn@3D-NPC delivers a reversible ...capacity of 740 mAh g–1 after 200 cycles at a current density of 200 mA g–1, corresponding to a capacity retention of 85% (against the second capacity) and high rate capability (300 mAh g–1 at 5 A g–1). Compared to the Sn nanoparticles (SnNPs), such improvements are attributed to the 3D porous and conductive framework. The whole structure can provide not only the high electrical conductivity that facilities the electron transfer but also the elasticity that will suppress the volume expansion and aggregation of SnNPs during the charge and discharge process. This work opens a new application of metal–organic frameworks in energy storage.
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IJS, KILJ, NUK, PNG, UL, UM
Novel SnO
2–
x
/g-C
3
N
4
heterojunction nanocomposites composed of reduced SnO
2–
x
nanoparticles and exfoliated g-C
3
N
4
nanosheets were prepared by a convenient one-step pyrolysis method. The ...structural, morphological, and optical properties of the as-prepared nanocomposites were characterized in detail, indicating that the aggregation of g-C
3
N
4
nanosheets was prevented by small, well-dispersed SnO
2–
x
nanoparticles. The ultraviolet–visible spectroscopy absorption bands of the nanocomposites were shifted to a longer wavelength region than those exhibited by pure SnO
2
or g-C
3
N
4
. The charge transfer and recombination processes occurring in the nanocomposites were investigated using linear scan voltammetry and electrochemical impedance spectroscopy. Under 30-W visible-light-emitting diode irradiation, the heterojunction containing 27.4 wt.% SnO
2–
x
exhibited the highest photocurrent density of 0.0468 mA·cm
–2
, which is 33.43 and 5.64 times larger than that of pure SnO
2
and g-C
3
N
4
, respectively. The photocatalytic activity of the heterojunction material was investigated by degrading rhodamine B under irradiation from the same light source. Kinetic study revealed a promising degradation rate constant of 0.0226 min
−1
for the heterojunction containing 27.4 wt.% SnO
2–
x
, which is 32.28 and 5.79 times higher than that of pure SnO
2
and g-C
3
N
4
, respectively. The enhanced photoelectrochemical and photocatalytic performances of the nanocomposite may be due to its appropriate SnO
2–
x
content and the compact structure of the junction between the SnO
2–
x
nanoparticles and the g-C
3
N
4
nanosheets, which inhibits the recombination of photogenerated electrons and holes.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Under development for next‐generation wearable electronics are flexible, knittable, and wearable energy‐storage devices with high energy density that can be integrated into textiles. Herein, ...knittable fiber‐shaped zinc–air batteries with high volumetric energy density (36.1 mWh cm−3) are fabricated via a facile and continuous method with low‐cost materials. Furthermore, a high‐yield method is developed to prepare the key component of the fiber‐shaped zinc–air battery, i.e., a bifunctional catalyst composed of atomically thin layer‐by‐layer mesoporous Co3O4/nitrogen‐doped reduced graphene oxide (N‐rGO) nanosheets. Benefiting from the high surface area, mesoporous structure, and strong synergetic effect between the Co3O4 and N‐rGO nanosheets, the bifunctional catalyst exhibits high activity and superior durability for oxygen reduction and evolution reactions. Compared to a fiber‐shaped zinc–air battery using state‐of‐the‐art Pt/C + RuO2 catalysts, the battery based on these Co3O4/N‐rGO nanosheets demonstrates enhanced and stable electrochemical performance, even under severe deformation. Such batteries, for the first time, can be successfully knitted into clothes without short circuits under external forces and can power various electronic devices and even charge a cellphone.
Knittable fiber‐shaped zinc–air batteries based on atomically thin mesoporous Co3O4 layers strongly coupled with nitrogen‐doped reduced graphene oxide nanosheets as bifunctional catalysts of the air electrodes are developed and can be fabricated by a quick, facile, and continuous method. These high‐energy‐density batteries can be knitted into clothes and used as the power supply for wearable electronic devices.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Direct Z-scheme NiTiO3/g-C3N4 heterojunctions were successfully assembled by using simple calcination method and the photoelectrochemical and photocatalytic performance were investigated by light ...emitting diode (LED). The photoanode composed by the heterojunction with about 50 wt % NiTiO3 content exhibits the best photoelectrochemical activity with photoconversion efficiency up to 0.066%, which is 4.4 and 3.13 times larger than NiTiO3 or g-C3N4. The remarkably enhanced photoelectrochemical and photocatalytic activity of the heterojunction can be due to the efficiently photogenerated electron–hole separation by a Z-scheme mechanism.
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IJS, KILJ, NUK, PNG, UL, UM
High-capacity and high-power nickel-based cathode materials have become the principal candidates for a lithium-ion energy storage system powering electrified transportation units. With high nickel ...content, the cathodes are of great interest for delivering the desired specific energy and energy density. However, the cells still suffer from fast capacity decay and low thermal-abuse tolerance to high voltage. At the highly delithiated state, the damage in the cell is mainly from severe parasitic reactions, including the oxygen evolution reaction in the cathode and oxidization of the organic electrolyte. These side reactions rapidly weaken the system's rate capacity and cyclability. Solutions are being sought to provide safe operation and practical application. Three strategies have proven to be encouraging choices: surface coating, a core-shell structure, and a concentration gradient structure. For each strategy, the material architecture, fabrication procedure, operation principle, advances, and challenges are discussed in this review. The prospects for further developments are also summarized.
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In order to meet the increasing demand for electric vehicles, a powerful lithium-ion battery is required to deliver high capacity and energy density. Among all the components in a lithium-ion cell, nickel-rich cathodes have been widely developed as a dominant element determining the overall cell performance. The capacity delivered by the cathode is highly dependent on the nickel content. Although such cathodes indeed guarantee high capacity and energy density, thermal stability and cyclability are still poor because of structural instability and parasitic reactions. The poor cycle life cannot meet the requirement for thousands of cycles or 15 years of calendar life. With the aim of achieving high capacity with satisfactory battery lifetime, stabilization of the nickel-based cathode has become a globally competitive topic. The most encouraging strategies and prospects for further developments are summarized in this review.
The cycling stability and rate capacity of a nickel-rich lithium battery are effectively improved through stabilization of the cathode by coating protection, structure modification, electrolyte optimization, and other strategies. Both electrochemical and kinetic investigations have confirmed the improved stability to be attributed to suppression of the parasitic reaction between the cathode components and electrolyte. The enhanced electrochemical performance makes the corresponding energy storage systems applicable for the global electric-vehicle market.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The search for earth‐abundant and high‐performance electrode materials for sodium‐ion batteries represents an important challenge to current battery research. 2D transition metal dichalcogenides, ...particularly MoS2, have attracted increasing attention recently, but few of them so far have been able to meet expectations. In this study, it is demonstrated that another phase of molybdenum sulfide—amorphous chain‐like MoS3—can be a better choice as the anode material of sodium‐ion batteries. Highly compact MoS3 particles infiltrated with carbon nanotubes are prepared via the facile acid precipitation method in ethylene glycol. Compared to crystalline MoS2, the resultant amorphous MoS3 not only exhibits impressive gravimetric performance—featuring excellent specific capacity (≈615 mA h g−1), rate capability (235 mA h g−1 at 20 A g−1), and cycling stability but also shows exceptional volumetric capacity of ≈1000 mA h cm−3 and an areal capacity of >6.0 mA h cm−2 at very high areal loadings of active materials (up to 12 mg cm−2). The experimental results are supported by density functional theory simulations showing that the 1D chains of MoS3 can facilitate the adsorption and diffusion of Na+ ions. At last, it is demonstrated that the MoS3 anode can be paired with an Na3V2(PO4)3 cathode to afford full cells with great capacity and cycling performance.
The preparation of compact MoS3 particles via the facile acid precipitation method leads to a high‐performance sodium‐ion battery anode material. Contrary to the well‐studied layered MoS2, amorphous MoS3 consists of Mo chains bridged by sulfide and disulfide ligands. It demonstrates improved electrochemical performance with large specific capacity, excellent rate capability and satisfactory cycling stability.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Fullerene‐based carbons are promising electrode materials for supercapacitors due to their unique carbon structures and tunable architectures at the molecular level. By introducing various functional ...groups with many elements on the fullerene cages, diverse in situ metal/nonmetal‐doped carbon materials with enhanced pseudocapacitances and/or double layer capacitances can be prepared. In the present work, a fullerene derivative, ferrocenylpyrrolidine C60, containing nitrogen and iron, is chosen as the only precursor. A unique microstructure is fabricated by a liquid–liquid interfacial precipitation process. Subsequently, a facile, one‐step annealing of the microstructure at different temperatures is performed. A series of in situ N and Fe‐codoped laminated 3D hierarchical carbon composites in the shape of a cross are successfully synthesized. The as‐prepared N and Fe‐codoped carbon material treated at 700 °C exhibits a high specific capacitance of 505.4 F g−1 at 0.1 A g−1. To the best knowledge, this is the highest supercapacitor capacitance based on fullerene electrode materials. The use of a fullerene derivative as an in‐situ doped carbon for applications in energy storage opens a new avenue for developing future synthetic strategies to extend the repertoire of electrode materials with high performance.
N and Fe‐codoped cross‐like 3D hierarchical carbon materials for high‐performance supercapacitors are successfully synthesized from an in‐situ doped fullerene, ferrocenylpyrrolidine C60 containing nitrogen and iron. The use of a fullerene derivative for applications in energy storage opens a new avenue for developing new synthetic strategies to extend the repertoire of electrode materials with remarkable performance.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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