Lithium sulfur batteries with high energy densities are promising next-generation energy storage systems. However, shuttling and sluggish conversion of polysulfides to solid lithium sulfides limit ...the full utilization of active materials. Physical/chemical confinement is useful for anchoring polysulfides, but not effective for utilizing the blocked intermediates. Here, we employ black phosphorus quantum dots as electrocatalysts to overcome these issues. Both the experimental and theoretical results reveal that black phosphorus quantum dots effectively adsorb and catalyze polysulfide conversion. The activity is attributed to the numerous catalytically active sites on the edges of the quantum dots. In the presence of a small amount of black phosphorus quantum dots, the porous carbon/sulfur cathodes exhibit rapid reaction kinetics and no shuttling of polysulfides, enabling a low capacity fading rate (0.027% per cycle over 1000 cycles) and high areal capacities. Our findings demonstrate application of a metal-free quantum dot catalyst for high energy rechargeable batteries.
Co-intercalation reactions make graphite as promising anodes for sodium ion batteries, however, the high redox potentials significantly lower the energy density. Herein, we investigate the factors ...that influence the co-intercalation potential of graphite and find that the tuning of the voltage as large as 0.38 V is achievable by adjusting the relative stability of ternary graphite intercalation compounds and the solvent activity in electrolytes. The feasibility of graphite anode in sodium ion batteries is confirmed in conjunction with Na
VPO
F
cathodes by using the optimal electrolyte. The sodium ion battery delivers an improved voltage of 3.1 V, a high power density of 3863 W kg
, negligible temperature dependency of energy/power densities and an extremely low capacity fading rate of 0.007% per cycle over 1000 cycles, which are among the best thus far reported for sodium ion full cells, making it a competitive choice in large-scale energy storage systems.
Calcium ion batteries (CIBs) are pursued as potentially low‐cost and safe alternatives to current Li‐ion batteries due to the high abundance of calcium element. However, the large and divalent nature ...of Ca2+ leads to strong interaction with intercalation hosts, sluggish ion diffusion kinetics and low power output. Herein, a small molecular organic anode is reported, tetracarboxylic diimide (PTCDI), involving carbonyl enolization (CO↔CO−) in aqueous electrolytes, which bypasses the diffusion difficulties in intercalation‐type electrodes and avoid capacity sacrifice for polymer organic electrodes, thus manifesting rapid and high Ca storage capacities. In an aqueous Ca‐ion cell, the PTCDI presents a reversible capacity of 112 mAh g−1, a high‐capacity retention of 80% after 1000 cycles and a high‐power capability at 5 A g−1, which rival the state‐of‐the‐art anode materials in CIBs. Experiments and simulations reveal that Ca ions are diffusing along the a axis tunnel to enolize carbonyl groups without being entrapped in the aromatic carbon layers. The feasibility of PTCDI anodes in practical CIBs is demonstrated by coupling with cost‐effective Prussian blue analogous cathodes and CaCl2 aqueous electrolyte. The appreciable Ca storage performance of small molecular crystals will spur the development of green organic CIBs.
PTCDI is first employed as the anode for aqueous calcium‐ion batteries. The guest‐host chemical bonding and structure evolution of molecular crystals are clearly clarified by simulation and in(ex)‐situ spectroscopy characterizations. This study extends the boundary of molecular crystal systems for electrochemistry to construct high‐performance aqueous multivalent ion batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Anatase TiO2 is considered as one of the promising anodes for sodium‐ion batteries because of its large sodium storage capacities with potentially low cost. However, the precise reaction mechanisms ...and the interplay between surface properties and electrochemical performance are still not elucidated. Using multimethod analyses, it is herein demonstrated that the TiO2 electrode undergoes amorphization during the first sodiation and the amorphous phase exhibits pseudocapacitive sodium storage behaviors in subsequent cycles. It is also shown that the pseudocapacitive sodium storage performance is sensitive to the nature of solid electrolyte interphase (SEI) layers. For the first time, it is found that ether‐based electrolytes enable the formation of thin (≈2.5 nm) and robust SEI layers, in contrast to the thick (≈10 nm) and growing SEI from conventional carbonate‐based electrolytes. First principle calculations suggest that the higher lowest unoccupied molecular orbital energies of ether solvents/ion complexes are responsible for the difference. TiO2 electrodes in ether‐based electrolyte present an impressive capacity of 192 mAh g−1 at 0.1 A g−1 after 500 cycles, much higher than that in carbonate‐based electrolyte. This work offers the clarified picture of electrochemical sodiation mechanisms of anatase TiO2 and guides on strategies about interfacial control for high performance anodes.
A thin and robust solid electrolyte interphase formed on a TiO2 surface that is enabled by using ether electrodes is demonstrated in Na‐ion batteries. This electrolyte/electrolyte interface, which is superior to conventional carbonate electrolyte, results in largely different electrochemical performances. The fundamental origin of the difference is unveiled through the combination of intensive experimental characterizations and first principles calculations.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Ca‐ion batteries (CIBs) have been considered a promising candidate for the next‐generation energy storage technology owing to the abundant calcium element and the low reduction potential of Ca2+/Ca. ...However, the large size and divalent nature of Ca2+ induce significant volume change and sluggish ion mobility in intercalation cathodes, leading to poor reversibly and low energy/power densities for CIBs. Herein, a polyanionic Na superionic conduction (NASICON)‐typed Na‐vacant Na1V2(PO4)2F3 (N1PVF3) with sufficient interstitial spaces is reported as ultra‐stable and high‐energy Ca ion cathodes. The N1PVF3 delivers exceptionally high Ca storage capacities of 110 and 65 mAh g‐1 at 10 and 500 mA g–1, respectively, and a record‐long cyclability of 2000 cycles. More interestingly, by tailoring the fluorine content in N1PVFx (1 ≤ x ≤ 3), the high working potential of 3.5 V versus Ca2+/Ca is achievable. In conjunction with Ca metal anode and a compatible electrolyte, Ca metal batteries with N1VPF3 cathodes are constructed, which deliver an initial energy density of 342 W h kg‐1, representing one of the highest values thus far reported for CIBs. Origins of the uncommonly stable and high‐power capabilities for N1PVF3 are elucidated as the small volume changes and low cation diffusion barriers among the cathodes.
The merits of covalent open framework with large tunnel sites, substantial Na interstitial vacancies, and fluorine‐rich phase indicate Na1V2(PO4)2F3 (N1VPF3) as an excellent candidate for Ca ion storage with high redox potentials. As a proof of concept, the N1VPF3 cathode demonstrates exceptionally high energy density and long‐term cyclic stability in Ca ion batteries.
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•The fundamentals of LSBs, carbon nanomaterials and sulfur/carbon cathodes are discussed.•Design principles of nanocarbon to overcome the intrinsic challenges of LSBs are ...summarized.•The gap between the current achievements and the practical LSBs in real-market is bridged.
Taking advantage of a high theoretical energy density of 2567 Wh kg-1, lithium sulfur batteries (LSBs) have been considered promising candidates for next-generation energy storage systems. Nevertheless, challenging issues involving both sulfur cathode and lithium anode hinder their practical applications, which are followed by the extensive research efforts to resolve them. A wide variety of carbon nanomaterials with different characteristics has played an important role in enhancing the performance of LSBs via immobilizing sulfur in cathodes, accommodating the volume expansion of sulfur, enhancing the reaction kinetics and stabilizing lithium anodes. This report overviews the state-of-the-art progress in designing and fabricating nanocarbon for advanced LSBs with particular focuses on the correlations among porosity, electrical conductivity and surface chemistry as some of the most critical factors. More importantly, statistical analysis of electrochemical performance of batteries collected from literatures allows us to identify substantial disparities between the current achievements and the requirements for real-world applications. In an effort to bridge this gap, we highlight recent advances in the design of LSBs with improved sulfur loading, enhanced charge transfer and minimized electrolyte/sulfur ratio. Conclusions and perspectives for future development of nanocarbon in LSBs are proposed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Calcium‐ion batteries (CIBs) are considered to be promising next‐generation energy storage systems because of the natural abundance of calcium and the multivalent calcium ions with low redox ...potential close to that of lithium. However, the practical realization of high‐energy and high‐power CIBs is elusive owing to the lack of suitable electrodes and the sluggish diffusion of calcium ions in most intercalation hosts. Herein, it is demonstrated that calcium‐ion intercalation can be remarkably fast and reversible in natural graphite, constituting the first step toward the realization of high‐power calcium electrodes. It is shown that a graphite electrode exhibits an exceptionally high rate capability up to 2 A g−1, delivering ≈75% of the specific capacity at 50 mA g−1 with full calcium intercalation in graphite corresponding to ≈97 mAh g−1. Moreover, the capacity stably maintains over 200 cycles without notable cycle degradation. It is found that the calcium ions are intercalated into graphite galleries with a staging process. The intercalation mechanisms of the “calciated” graphite are elucidated using a suite of techniques including synchrotron in situ X‐ray diffraction, nuclear magnetic resonance, and first‐principles calculations. The versatile intercalation chemistry of graphite observed here is expected to spur the development of high‐power CIBs.
Graphite as a reliable anode material for calcium‐ion batteries is realized. By selecting a proper dimethylacetamide‐based electrolyte, reversible Ca (de)insertion is enabled in graphite at room temperature with large Ca‐storage capacities, remarkable reversibility, and exceptionally high power capability (≈75% capacity retention at 2 A g−1 to that at 50 mA g−1).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The emergence of flexible and wearable electronic devices with shape amenability and high mobility has stimulated the development of flexible power sources to bring revolutionary changes to daily ...lives. The conventional rechargeable batteries with fixed geometries and sizes have limited their functionalities in wearable applications. The first‐ever graphene‐based fibrous rechargeable batteries are reported in this work. Ultralight composite fibers consisting of reduced graphene oxide/carbon nanotube filled with a large amount of sulfur (rGO/CNT/S) are prepared by a facile, one‐pot wet‐spinning method. The liquid crystalline behavior of high concentration GO sheets facilitates the alignment of rGO/CNT/S composites, enabling rational assembly into flexible and conductive fibers as lithium–sulfur battery electrodes. The ultralight fiber electrodes with scalable linear densities ranging from 0.028 to 0.13 mg cm−1 deliver a high initial capacity of 1255 mAh g−1 and an areal capacity of 2.49 mAh cm−2 at C/20. A shape‐conformable cable battery prototype demonstrates a stable discharge characteristic after 30 bending cycles.
A freestanding and ultralight reduced graphene oxide (rGO)/carbon nanotube (CNT)/sulfur composite fibers are prepared by wet‐spinning as the cathode for lithium–sulfur batteries (LSBs). The liquid crystallinity of high concentration GO sheets enables rational assembly of rGO/CNT/S as flexible, conductive fibers. A cable LSB prototype comprising rGO/CNT/S cathode and lithium wire anode demonstrates excellent flexibility and stable static discharge performance.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Sodium metal batteries are promising next‐generation energy storage technology by using energy‐dense and affordable Na metal anodes, yet suffering uncontrollable Na dendritic growth issues. Herein, ...Au nanoparticle@hollow amorphous carbon tube yolk/shell arrays (Au/HCT‐CC) is rationally designed on carbon cloth as a dynamic host. In situ transmission electron microscopy observations reveal a regulated dendrite‐free Na metal plating/stripping within the Au/HCT‐CC host. The self‐confinement of Na metal deposition in the hollow carbon can further stabilize the electrolyte/electrode interface and homogenize Na ion flux, as evidenced by rigorous experimental and theoretical characterizations, thus successfully accommodating the hurdles to Na metal anodes. When cycling in half cells, the Au/HCT‐CC electrodes deliver remarkably high coulombic efficiencies (CEs) of 99.96% over 2200 h at 5 mA cm−2. The high CE of 99.54% is preserved even under harsh cycling conditions of 10 mA cm−2 and 20 mAh cm−2 for 250 cycles. These values rival the state‐of‐the‐art electrochemical performance for Na metal anodes in literature. Finally, the practical feasibility of the new anode is demonstrated by cycling in Na3V2(PO4)3@C||Na‐Au/HCT‐CC full cells over 900 cycles with an extremely low capacity degradation rate of 0.017% per cycle.
3D hollow amorphous carbon tube arrays embedded with Au nanoparticles are directly grown on carbon cloth (Au/HCT‐CC) for sodium metal anode. In situ TEM, in situ optical microscopy, and theoretical simulations clearly uncover that sodiophilic Au nanoparticles can induce dendrite‐free Na metal plating/stripping within the Au/HCT‐CC substrate, providing a testament to its remarkable electrochemical performance.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Calcium (Ca)-based rechargeable batteries (CRBs) have been considered one of the most promising post-lithium ion battery technologies because of the natural abundance of Ca, high volumetric capacity ...compared to monovalent metal batteries, and the low reduction potential of Ca
2+
/Ca. Recently, a breakthrough of Ca reversible plating and stripping at the Ca metal anode in carbonate electrolytes has induced the study of Ca rechargeable batteries. This critical review presents the state-of-the-art progress made in exploring potential electrode materials including Ca metal anodes, alternative graphite and alloy-type anodes, and cathode materials undergoing interaction or conversion reactions. Suitable electrolytes are also required to ensure the compatibility of each cell component, which is essential toward high-performance Ca full batteries. The performance assessment and mechanism analysis are further discussed to evaluate the current progress and existing challenges regarding the performance promise and insufficient understanding of the Ca battery technology. To conclude, this review provides a comprehensive understanding of the underlying mechanisms and challenges that need to be addressed to promote the commercialization of CRBs.
The recent advances in anode and cathode materials combined with the compatibility of electrolytes are systematically reviewed for calcium (Ca)-based rechargeable batteries, focusing on their cell design, battery performance, characterization and future opportunities.
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