Noticeable pseudo‐capacitance behavior out of charge storage mechanism (CSM) has attracted intensive studies because it can provide both high energy density and large output power. Although cyclic ...voltammetry is recognized as the feasible electrochemical technique to determine it quantitatively in the previous works, the results are inferior due to uncertainty in the definitions and application conditions. Herein, three successive treatments, including de‐polarization, de‐residual and de‐background, as well as a non‐linear fitting algorithm are employed for the first time to calibrate the different CSM contribution of three typical cathode materials, LiFePO4, LiMn2O4 and Na4Fe3(PO4)2P2O7, and achieve well‐separated physical capacitance, pseudo‐capacitance and diffusive contributions to the total capacity. This work can eliminate misunderstanding concepts and correct ambiguous results of the pseudo‐capacitance contribution and recognize the essence of CSM in electrode materials.
Well‐separated physical capacitance, pseudo‐capacitance, and diffusive capacity are achieved from the CV curves of typical electrode materials for metal‐ion batteries after three successive treatments including de‐polarization, de‐residual and de‐background as well as non‐linear fitting calculation, offering a more rational and reliable method to calculate the pseudo‐capacitance contribution.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Sodium-ion battery has emerged as one of most promising technologies for large-scale energy storage system, and hence has stimulated extensive exploration of applicable electrode materials with low ...cost and superb electrochemical properties. Herein, 3D graphene decorated Na4Fe3(PO4)2(P2O7) microspheres as a low-cost and environmentally friendly cathode material are synthesized by using a facile spray-drying method. The as-prepared NFPP@rGO composite exhibits a high reversible capacity of 128 mAh g−1 at 0.1 C, a superior rate capability (35 mAh g−1 at 200 C), and a long cycling life (62.3% capacity retention over 6000 cycles at 10 C). The excellent electrochemical performance is attributed to combined advantages of graphene coating on the surface of nanoparticles and the flexible 3D graphene network, which not only improve the electronic conductivity, but also accommodate the structural stress of the material during charging and discharging. Therefore, the NFPP@rGO microsphere with superior electrochemical performances, low-cost raw materials, simple synthetic route and high thermal stability is considered as a very attractive cathode electrode for sodium ion battery.
Display omitted
•NFPP@rGO microsphere is synthesized by using a facile spray-drying method.•The NFPP@rGO composite exhibits high electrochemical performance for Na ion storage.•The excellent performance is attributed to combined advantages of graphene coating and 3D network.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The multi-scenario simulation of the coupling coordination degree between the social-human-ecological system.•The research incorporate the human system innovatively into the socio-ecological ...system.•Counties and districts have varied CCD development pathways.•Simply increasing the policy intensity of a single subsystem is inadequate.•The results provide guidance for the formation of high-quality and sustainable socio-economic policies.
Due to the lack of scientific and systematic thinking in the early stages of high-quality urbanisation, the interaction and stress between the social-human-ecological (SHE)11SHE social-human-ecological. system intensified, resulting in a series of problems related to the low level of ecological environment and the imbalanced socio-economic development. It is crucial to enhance the safety, health, and well-being of city dwellers, as well as to promote the sustainable development of the region. Based on complex systems science, using the Three Gorges Reservoir Area (TGRA)22TGRA Three Gorges Reservoir Area. as an instance, this study develops a multidimensional coupling conceptual model of the SHE system, employs the system dynamics (SD)33SD system dynamics. method to clarify the SHE system’s causal feedback mechanism, and simulates the coupling coordination degree (CCD)44CCD coupling coordination degree. from 2010 to 2030. Simultaneously, eight scenarios are created to improve the system’s CCD by modifying factors. According to historical and sensitivity test findings, the SD model used in this work can effectively represent the SHE system’s dynamic coupling and interaction connection. Furthermore, under the comprehensive development scenario that takes into account the protection of the ecological environment, human intelligent regulation, and socio-economic development, the TGRA has the biggest growth in CCD. As a result, raising the policy intensity of a single subsystem is insufficient. Balancing policy implementation for each subsystem is advantageous to improving the coupling coordination of the SHE system in the TGRA. The study is of significant importance for achieving high-quality socio-economic development and sustainable ecological management in the TGRA region.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We report for the first time a zero-strain cathode, Na4Fe7(PO4)6, for sodium–ion batteries (SIBs). This new iron-based polyanionic cathode delivers a reversible capacity of 66.5 mA h g−1 at 5 mA g−1 ...with almost 100% capacity retention over 1000 cycles under 200 mA g−1, and the outstanding performance benefits from single-phase-transition processes with a tiny volume change of only ∼0.24%.
Multivalent metal ion (Mg2+, Zn2+, Ca2+, and Al3+) batteries (MMIBs) emerged as promising technologies for large-scale energy storage systems in recent years due to the abundant metal reserves in the ...Earth’s crust and potentially low cost. However, the lack of high-performance electrode materials is still the main obstacle to the development of MMIBs. As a newly large family of two-dimensional transition metal carbides, nitrides, and carbonitrides, MXenes have attracted growing focus in the energy storage field because of their large specific surface area, excellent conductivity, tunable interlayer spaces, and compositional diversity. In particular, the multifunctional chemistry and superior hydrophilicity enable MXenes to serve not only as electrode materials but also as important functional components for heterojunction composite electrodes. Herein, the advances of MXene-based materials since its discovery for MMIBs are summarized, with an emphasis on the rational design and controllable synthesis of MXenes. More importantly, the fundamental understanding of the relationship between the morphology, structure, and function of MXenes is highlighted. Finally, the existing challenges and future research directions on MXene-based materials toward MMIBs application are critically discussed and prospected.
Large-scale energy storage using sodium ion batteries (SIBs) as a hub for the conversion of renewable energy has become a topic of great importance. However, the application of SIBs is hindered by ...low energy density arising from inferior capacity and operation voltage. In this regard, vanadium-based phosphate polyanions with multiple valence changes (III–V), high redox potential, abundant resources, spacious frame structure, and remarkable thermal stability are promising avenues to address this dilemma. In this review, following the principle of electronic structure and function relationship, we summarize the recent progress in phosphates, pyrophosphates, fluorophosphates, and mixed polyanions of vanadium-centered polyanionic materials for SIBs. This review may provide comprehensive understanding and guidelines to further construct high performance, low-cost sodium-ion batteries.
Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework, cost‐effectiveness, and high energy density. However, the understanding of the crystal ...structure is scarce and only a limited candidates have been reported so far. In this work, we found for the first time that a continuous solid solution, Na4−αFe2+α/2(P2O7)2 (0 ≤ α ≤ 1, could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P2O7 unchanged. In particular, a novel off‐stoichiometric Na3Fe2.5(P2O7)2 is thus proposed, and its structure, energy storage mechanism, and electrochemical performance are extensively investigated to unveil the structure–function relationship. The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g−1, a working voltage of 2.9 V (vs. Na+/Na), the retention of 89.2% of the initial capacity after 500 cycles, and enhanced rate capability of 51 mAh g−1 at a current density of 1600 mA g−1. This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na4−αFe2+α/2(P2O7)2, offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.
Iron‐based pyrophosphate (Na4−αFe2+α/2(P2O7)2) is an attractive cathode for sodium‐ion batteries due to its cost‐effectiveness, feasible channels, and high operation voltage. Extending the solid solution range of Na4−αFe2+α/2(P2O7)2 enables generation of a novel off‐stoichiometric phase. Structural resolution, theoretical calculations, and sodium storage performance are comprehensively studied to disclose its structure–property relationship in sodium‐ion batteries.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The increasing demands for renewable energy to substitute traditional fossil fuels and related large‐scale energy storage systems (EES) drive developments in battery technology and applications ...today. The lithium‐ion battery (LIB), the trendsetter of rechargeable batteries, has dominated the market for portable electronics and electric vehicles and is seeking a participant opportunity in the grid‐scale battery market. However, there has been a growing concern regarding the cost and resource availability of lithium. The sodium‐ion battery (SIB) is regarded as an ideal battery choice for grid‐scale EES owing to its similar electrochemistry to the LIB and the crust abundance of Na resources. Because of the participation in frequency regulation, high pulse‐power capability is essential for the implanted SIBs in EES. Herein, a comprehensive overview of the recent advances in the exploration of high‐power cathode and anode materials for SIB is presented, and deep understanding of the inherent host structure, sodium storage mechanism, Na+ diffusion kinetics, together with promising strategies to promote the rate performance is provided. This work may shed light on the classification and screening of alternative high rate electrode materials and provide guidance for the design and application of high power SIBs in the future.
The sodium‐ion battery (SIB) is an ideal choice for large‐scale energy storage, and high pulse‐power capability is essentially required for its applications. The recent progress of high‐power SIBs including cathodes, anode materials, electrolytes, and aqueous systems is reviewed. Special attention is given on understanding the inherent host structure, sodium storage mechanism, Na+ diffusion kinetics, and strategies to promote the rate performance.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Multi-component hollow structures with attractive physicochemical properties, often show superior electrochemical performance in alkali-ion batteries. Herein, a template-directed strategy is proposed ...for synthesis of multi-component hollow nanosphere with Co2P/MoSe2 confined in N-doped carbon (Co2P/MoSe2@NC). This structure markedly improves the kinetics, provides sufficient active sites and accommodates volume expansion, for the large-sized K+/Na+ storage, which is proved by the in-situ and ex-situ transmission electron microscopy measurements. As for sodium storage, a capacity of 230 mAh g−1 over 1500 cycles can be retained at current of 2.0 A g−1, with a capacity retention of 83%. In terms of K+ storage, Co2P/MoSe2@NC anodes display excellent rate capability and ultra-long cycling performance (177.6 mAh g−1 at 1.0 A g−1 for 5000 cycles with a capacity retention of 75%). Based on the analysis of electrode process by comparison of dQ/dV curves and theoretical calculations, the intercalation-conversion reaction for K+ storage is more reversible and the weaker adsorption of K+ on the Co2P/MoSe2 interface can guarantee the stable storage of the K+-ions. High energy density of 43.34 Wh kg−1 at power densities of 22263.7 W kg−1 is delivered in the Co2P/MoSe2@NC//AC potassium-ion hybrid supercapacitor. This indicates that a selenide/phosphide combination can exert useful synergistic effects on the large-sized K+/Na+ storage, and is a promising anode candidate.
Display omitted
•A template-directed strategy was used to construct multi-component hollow structures.•Co2P/MoSe2 confined in NC framework was designed in one-step selenization process.•The hollow nanosphere with Co2P and MoSe2 promotes the high-rate storage of Na+/K+.•K+ storage is stable for Co2P/MoSe2@NC based on dQ/dV analysis and DFT calculation.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Single‐crystalline cathode materials have attracted intensive interest in offering greater capacity retention than their polycrystalline counterparts by reducing material surfaces and phase ...boundaries. However, the single‐crystalline LiCoO2 suffers severe structural instability and capacity fading when charged to high voltages (4.6 V) due to Co element dissolution and O loss, crack formation, and subsequent electrolyte penetration. Herein, by forming a robust cathode electrolyte interphase (CEI) in an all‐fluorinated electrolyte, reversible planar gliding along the (003) plane in a single‐crystalline LiCoO2 cathode is protected due to the prevention of element dissolution and electrolyte penetration. The robust CEI effectively controls the performance fading issue of the single‐crystalline cathode at a high operating voltage of 4.6 V, providing new insights for improved electrolyte design of high‐energy‐density battery cathode materials.
Single‐crystalline cathode materials have attracted intensive interest. However, the single‐crystalline LiCoO2 suffers severe structural instability and capacity fading when charged to high voltages (4.6 V vs Li/Li+) due to Co and O element dissolution, crack formation, and electrolyte penetration. In this work, the above problems are inhibited by forming a robust cathode electrolyte interphase (CEI) on the surface of LiCoO2.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
