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1.
    
Rechargeable lithium ion battery (LIB) has dominated the energy market from portable electronics to electric vehicles, but the fast‐charging remains challenging. The safety concerns of lithium deposition on graphite anode or the decreased energy density using Li4Ti5O12 (LTO) anode are incapable to satisfy applications. Herein, the sulfurized polyacrylonitrile (SPAN) is explored for the first time as a high capacity and safer anode in LIBs, in which the high voltage cathode of LiNi1/3Co1/3Mn1/3O2 (NCM‐H) is further introduced to configure a new SPAN|NCM‐H battery with great fast‐charging features. The LIB demonstrates a good stability with a high capacity retention of 89.7% after 100 cycles at a high voltage of 3.5 V (i.e., 4.6 V vs Li+/Li). Particularly, the excellent rate capability is confirmed and 78.7% of initial capacity can still be delivered at 4.0C. In addition, 97.6% of the battery capacity can be charged within 2.0C, which is much higher than 80% in current fast‐charging application standards. The feature of lithiation potential (>1.0 V vs Li+/Li) of SPAN avoids the lithium deposition and improves the safety, while the high capacity over 640 mAh g?1 promises 43.5% higher energy density than that of LTO‐based battery, enabling its great competitiveness to conventional LIBs.  相似文献   

2.
    
Lithium metal anodes (LMAs) are promising for next-generation batteries but have poor compatibility with the widely used carbonate-based electrolytes, which is a major reason for their severe dendrite growth and low Coulombic efficiency (CE). A nitrate additive to the electrolyte is an effective solution, but its low solubility in carbonates is a problem that can be solved using a crown ether, as reported. A rubidium nitrate additive coordinated with 18-crown-6 crown ether stabilizes the LMA in a carbonate electrolyte. The coordination promotes the dissolution of NO3− ions and helps form a dense solid electrolyte interface that is Li3N-rich which guides uniform Li deposition. In addition, the Rb (18-crown-6)+ complexes are adsorbed on the dendrite tips, shielding them from Li deposition on the dendrite tips. A high CE of 97.1% is achieved with a capacity of 1 mAh cm−2 in a half cell, much higher than when using the additive-free electrolyte (92.2%). Such an additive is very compatible with a nickel-rich ternary cathode at a high voltage, and the assembled full battery with a cathode material loading up to 10 mg cm−2 shows an average CE of 99.8% over 200 cycles, indicating a potential for practical use.  相似文献   

3.
    
The ever-growing demand for low-cost, high-energy-density lithium-ion batteries (LIBs) makes high-nickel layered oxide cathodes, especially LiNiO2 (LNO), one of the most appealing candidates. However, poor structural and surface instability that leads to a short cycle life remains a formidable challenge. Herein, a systematic investigation of LNO performance in two different electrolytes (a conventional carbonate-based LP57 electrolyte and an ether-based localized high-concentration electrolyte (LHCE)) with different charge cut-off voltages is presented. These findings show that the cathode-electrolyte reactivity is the main factor dictating the performance degradation of LNO at high voltages rather than bulk integrity. While LHCE can provide good stability beyond 4.2 V with a robust, uniform solid–electrolyte interphase (SEI) layer on the Li-metal anode, there is no significant difference in cyclability at 4.15 V (96% capacity retention after 200 cycles) for both LP57 and LHCE. From LNO symmetric cells, carbonate-based electrolyte is found to be good for LNO stability while ether-based electrolyte is beneficial toward Li-metal anode. Thus, a suitable electrolyte or a low cut-off voltage is necessary to maintain a decent cycle life. Altogether, this work highlights the impact of electrolyte and cut-off voltage on LNO and Li-metal, which can help guide the development of cells based on LNO.  相似文献   

4.
    
Lithium‐rich layered oxides are considered as promising cathode materials for Li‐ion batteries with high energy density due to their higher capacity as compared with the conventional LiMO2 (e.g., LiCoO2, LiNiO2, and LiNi1/3Co1/3Mn1/3O2) layered oxides. However, why lithium‐rich layered oxides exhibit high capacities without undergoing a structural collapse for a certain number of cycles has attracted limited attention. Here, based on the model of Li2RuO3, it is uncovered that the mechanism responsible for the structural integrity shown by lithium‐rich layered oxides is realized by the flexible local structure due to the presence of lithium atoms in the transition metal layer, which favors the formation of O22?‐like species, with the aid of in situ extended X‐ray absorption fine structure (EXAFS), in situ energy loss spectroscopy (EELS), and density functional theory (DFT) calculation. This finding will open new scope for the development of high‐capacity layered electrodes.  相似文献   

5.
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6.
    
This work compares the intercalation of K, Na, and Li in KxVPO4F (x ～ 0). The KxVPO4F (x ～ 0) cathode delivers reversible capacities of ≈90–100 mAh g?1 in K, Na, and Li cells, at an average voltage of ≈4.33 V for K, ≈3.98 V for Na, and ≈3.96 V for Li. This is so far the highest average voltage known for a K‐intercalation cathode. The lower voltage of Li insertion compared to Na is attributable to undercoordinated Li ions in the KxVPO4F (x ～ 0) framework. While the material shows high rate capability for all the alkali ions, Li migration in KxVPO4F (x ～ 0) is more difficult than with Na and K. This work suggests that a large cavity is not always good for insertion of alkali ions and cathode materials need to be suitably tailored to each intercalating ion species.  相似文献   

7.
    
Li[Ni0.65Co0.13Mn0.22]O2 cathode with two‐sloped full concentration gradient (TSFCG), maximizing the Ni content in the inner part of the particle and the Mn content near the particle surface, is synthesized via a specially designed batch‐type reactor. The cathode delivers a discharge capacity of 200 mAh g?1 (4.3 V cutoff) with excellent capacity retention of 88% after 1500 cycles in a full‐cell configuration. Overall electrochemical performance of the TSFCG cathode is benchmarked against conventional cathode (CC) with same composition and commercially available Li[Ni0.8Co0.15Al0.05]O2 (NCA). The TSFCG cathode exhibits the best cycling stability, rate capability, and thermal stability of the three electrodes. Transmission electron microscopy analysis of the cycled TSFCG, CC, and NCA cathodes shows that the TSFCG electrode maintains both its mechanical and structural integrity whereas the NCA electrode nearly pulverizes due to the strain during cycling.  相似文献   

8.
    
Surface properties of electrode materials play a critical role in the function of batteries. Therefore, surface modifications, such as coatings, have been widely used to improve battery performance. Understanding how these coatings function to improve battery performance is crucial for both scientific research and applications. In this study the electrochemical performance of coated and uncoated LiNi0.5Mn1.5O4 (LNMO) electrodes is correlated with ensemble‐averaged soft X‐ray absorption spectroscopy (XAS) and spatially resolved scanning transmission electron microscopy‐electron energy loss spectroscopy (STEM‐EELS) to illustrate the mechanism of how ultrathin layer Al2O3 coatings improve the cycle life of LiNi0.5Mn1.5O4. Mn2+ evolution on the surface is clearly observed in the uncoated sample, which results from the reaction between the electrolytic solution and the surfaces of LiNi0.5Mn1.5O4 particles, and also possibly atomic structure reconstructions and oxygen loss from the surface region in LiNi0.5Mn1.5O4. The coating effectively suppresses Mn2+ evolution and improves the battery performance by decelerating the impedance buildup from the surface passivation. This study demonstrates the importance of combining ensemble‐averaged techniques (e.g., XAS) with localized techniques (e.g., STEM‐EELS), as the latter may yield unrepresentative information due to the limited number of studied particles, and sheds light on the design of future coating processes and materials.  相似文献   

9.
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10.
    
Nex-generation high-energy-density storage battery, assembled with lithium (Li)-metal anode and nickel-rich cathode, puts forward urgent demand for advanced electrolytes that simultaneously possess high security, wide electrochemical window, and good compatibility with electrode materials. Herein an intrinsically nonflammable electrolyte is designed by using 1 M lithium difluoro(oxalato)borate (LiDFOB) in triethyl phosphate (TEP) and N-methyl-N-propyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide [Pyr13][TFSI] ionic liquid (IL) solvents. The introduction of IL can bring plentiful organic cations and anions, which provides a cation shielding effect and regulates the Li+ solvation structure with plentiful Li+-DFOB− and Li+-TFSI− complexes. The unique Li+ solvation structure can induce stable anion-derived electrolyte/electrode interphases, which effectively inhibit Li dendrite growth and suppress side reactions between TEP and electrodes. Therefore, the LiNi0.9Co0.05Mn0.05O2 (NCM90)/Li coin cell with this electrolyte can deliver stable cycling even under 4.5 V and 60 °C. Moreover, a Li-metal battery with thick NCM90 cathode (≈ 15 mg cm−2) and thin Li-metal anode (≈ 50 µm) (N/P ≈ 3), also reveals stable cycling performance under 4.4 V. And a 2.2 Ah NCM90/Li pouch cell can simultaneously possess prominent safety with stably passing the nail penetration test, and high gravimetric energy density of 470 Wh kg−1 at 4.4 V.  相似文献   

11.
    
High-specific energy sulfur-based cathodes have attracted considerable interest in lithium batteries. Organosulfur cathodes offer inherent advantages of high element abundance and an extended cycling life, aligning with the evolving requirements of future energy storage devices. Over the past decade, research efforts have been devoted to optimizing electrochemical performance through the rich and tunable molecular structures of organosulfur compounds. To further advance the fundamental research and practical application of lithium-organosulfur batteries, a systematical analysis of the correlation between the molecular structures and electrochemical mechanisms of organosulfur cathodes is imperative. This involves deriving the key parameters at the cell level and investigating the feasibility. In this review, the thermodynamics, reaction processes, and electrochemical kinetics of organosulfur cathodes, grounded in fundamental theories of electrochemistry and materials science are discussed. Expanding the insights, comparisons among elemental sulfur, organosulfur, and n-type organic cathodes (e.g., carbonyl cathodes) are drawn. The gap between fundamentals and practical applications targeting 500 Wh kg−1 lithium organosulfur batteries is highlighted through energy density calculations and identification of key factors affecting pouch cells. Finally, potential strategies and prospects for the overall design of advanced lithium-organosulfur batteries are proposed, considering both theoretical foundations and practical implementations.  相似文献   

12.
    
Diversified and extended applications of lithium‐ion batteries demand the development of more enhanced materials that can be achieved by sophisticated synthetic methods. Combination of novel materials with strategic design of their shape on the nanometer scale enables a breakthrough to overcome problems experienced by present technologies. In this feature article, an overview is given of Mn‐based and polyanion‐based cathode materials with nanoscale features for lithium‐ion batteries as materials to replace conventional bulk cathode materials. Various synthetic methods coupled with nanostructuring as well as the benefits obtained from the nanostructure are described.  相似文献   

13.
    
The development of low‐cost, high‐energy cathodes from nontoxic, broadly available resources is a big challenge for the next‐generation rechargeable lithium or lithium‐ion batteries. As a promising alternative to traditional intercalation‐type chemistries, conversion‐type metal fluorides offer much higher theoretical capacity and energy density than conventional cathodes. Unfortunately, these still suffer from irreversible structural degradation and rapid capacity fading upon cycling. To address these challenges, here a versatile and effective strategy is harnessed for the development of metal fluoride–carbon (C) nanocomposite nanofibers as flexible, free‐standing cathodes. By taking iron trifluoride (FeF3) as a successful example, assembled FeF3–C/Li cells with a high reversible FeF3 capacity of 550 mAh g?1 at 100 mA g?1 (three times that of traditional cathodes, such as lithium cobalt oxide, lithium nickel cobalt aluminum oxide, and lithium nickel cobalt manganese oxide) and excellent stability (400+ cycles with little‐to‐no degradation) are demonstrated. The promising characteristics can be attributed to the nanoconfinement of FeF3 nanoparticles, which minimizes the segregation of Fe and LiF upon cycling, the robustness of the electrically conductive C network and the prevention of undesirable reactions between the active material and the liquid electrolyte using the composite design and electrolyte selection.  相似文献   

14.
    
The pursuit of rechargeable batteries with high energy density has triggered enormous efforts in developing cathode materials for lithium/sodium (Li/Na)-ion batteries considering their extremely high specific capacity. Many materials are being researched for battery applications, and transition metal oxide materials with remarkable electrochemical performance stand out among numerous cathode candidates for next-generation battery. Notwithstanding the merits, daunting challenges persist in the quest for further battery developments targeting lower cost, longer lifespan, improved energy density and enhanced safety. This is, in part, because the voltage hysteresis between the charge and discharge cycles, is historically avoided in intercalation electrodes because of its association with structural disorder and electrochemical irreversibility. Given the great potential of these materials for next-generation batteries, a review of the recent understanding of voltage hysteresis is timely. This review presents the origin of their undesirable behaviors and materials design criteria to mitigate them by integrating various schools of thought. A large amount of progressive characterization techniques related to voltage hysteresis are summarized from the literature, along with the corresponding measurable range used in their determination. Finally, promising design trends with eliminated voltage hysteresis are tentatively proposed to revive these important cathode materials toward practical applications.  相似文献   

15.
    
High-energy Ni-rich lithium transition metal oxides such as Li[Ni0.8Co0.1Mn0.1]O2 (NCM811) are appealing positive electrode materials for next-generation lithium batteries. However, the high sensitivity toward moist air during storage and the high reactivity with common organic electrolytes, especially at elevated temperatures, are hindering their commercial use. Herein, an effective strategy is reported to overcome these issues by coating the NCM811 particles with a lithium phosphonate functionalized poly(aryl ether sulfone). The application of this coating allows for a substantial reduction of lithium-based surface impurities (e.g., LiOH, Li2CO3) and, generally, the suppression of detrimental side reactions upon both storage and cycling. As a result, the coated NCM811-based cathodes reveal superior Coulombic efficiency and cycling stability at ambient and, particularly, at elevated temperatures up to 60 ° C (a temperature at which the non-coated NCM811 electrodes rapidly fail) owing to the formation of a stable cathode electrolyte interphase with enhanced Li+ transport kinetics and the well-retained layered crystal structure. These results render the herein presented coating strategy generally applicable for high-performance lithium battery cathodes.  相似文献   

16.
    
Moisture in air is a major obstacle for realizing practical lithium‐air batteries. Here, we integrate a hydrophobic ionic liquid (IL)‐based electrolyte and a cathode composed of electrolytic manganese dioxide and ruthenium oxide supported on Super P (carbon black) to construct a promising system for Li‐O2 battery that can be sustained in humid atmosphere (RH: 51%). A high discharge potential of 2.94 V and low charge potential of 3.34 V for 218 cycles are achieved. The outstanding performance is attributed to the synergistic effect of the unique hydrophobic IL‐based electrolyte and the composite cathode. This is the first time that such excellent performance is achieved in humid O2 atmosphere and these results are believed to facilitate the realization of practical lithium‐air batteries.  相似文献   

17.
Lithium-ion batteries (LIBs) adopting layered oxide cathodes with high nickel content (Ni ≥ 0.9) always suffer from extremely poor cycle life, especially at elevated temperatures and higher charging cut-off voltages. Adding small amounts of functional additives is considered to be one of the most economic and efficacious strategies to resolve this issue. Herein, cyano-groups are introduced innovatively into a siloxane to delicately synthesize a novel cyano-siloxane additive, namely 2,2,7,7-tetramethyl-3,6-dioxa-2,7-disilaoctane-4,4,5,5-tetracarbonitrile (TDSTCN). Encouragingly, 0.5 wt.% TDSTCN additive enables ultrahigh nickel LiNi0.9Co0.05Mn0.05O2/graphite (NCM90/Gr) full cells with dramatically increased cycle life, especially at an elevated temperature of 50 °C and a high charging cut-off voltage of 4.5 V. The characterizations reveal that the TDSTCN additive can scavenge HF and promote the formation of robust stable interface layers on NCM90 cathode and Gr anode due to the synergistic effects of cyano-groups and Si−O bonds. These results reveal the great significance of designing one single additive with several functional groups in enhancing the comprehensive electrochemical performances of high Ni LIBs.  相似文献   

18.
    
Electrode-electrolyte reactivity (EER) and particle cracking (PC) are considered two main causes of capacity fade in high-nickel layered oxide cathodes in lithium-based batteries. However, whether EER or PC is more critical remains debatable. Herein, the fundamental correlation between EER and PC is systematically investigated with LiNiO2 (LNO), the ultimate cobalt-free lithium layered oxide cathode. Specifically, EER is found more critical than secondary particle cracking (SPC) in determining the cycling stability of LNO; EER leads to primary particle cracking, but mitigates SPC due to the inhibition of H2-H3 phase transformation. Two surface degradation pathways are identified for cycled LNO under low and high EERs. A common blocking surface reconstruction layer (SRL) containing electrochemically-inactive Ni3O4 spinel and NiO rock-salt phases is formed on LNO in an electrolyte with a high EER; in contrast, an electrochemically-active SRL featuring regions of electron- and lithium-ion-conductive LiNi2O4 spinel phase is formed on LNO in an electrolyte with a low EER. These findings unveil the intrinsic degradation pathways of LNO cathode and are foreseen to provide new insights into the development of lithium-based batteries with a minimized EER and a maximized service life.  相似文献   

19.
    
Anion chemistry in electrolytes can greatly dictate the nature and quality of passivation layers on both cathode and anode surfaces. This will be more significant when it comes to highly reactive Li-metal anode and aggressive high-nickel cathodes. Herein, a competitive bi-anion activity is found in electrolytes with the co-existence of two anions, which leads to a controlled Li-salt decomposition kinetics and entirely favorable interphasial chemistry on both Li-metal anode and ultrahigh-nickel cathode. The proposed bi-anion localized high-concentration electrolytes are demonstrated to exhibit superior electrochemical compatibility toward Li metal and long-term cycling stabilities under both 4.4 and 4.6 V in Li-metal batteries with ultrahigh-nickel cathode. This study sheds fresh light on dendrite-free Li-metal anodes and provides guidance to achieve high-energy-density batteries.  相似文献   

20.
    
A facile synthesis of selenium sulfide (SeSx)/carbonized polyacrylonitrile (CPAN) composites is achieved by annealing the mixture of SeS2 and polyacrylonitrile (PAN) at 600 °C under vacuum. The SeSx molecules are confined by N‐containing carbon (ring) structures in the carbonized PAN to mitigate the dissolution of polysulfide and polyselenide intermediates in carbonate‐based electrolyte. In addition, formation of solid electrolyte interphase (SEI) on the surface of SeSx/CPAN electrode in the first cycle further prevents polysulfide and polyselenide intermediates from dissolution. The synergic restriction of SeSx by both CPAN matrix and SEI layer allows SeSx/CPAN composites to be charged and discharged in a low‐cost carbonate‐based electrolyte (LiPF6 in EC/DEC) with long cycling stability and high rate capability. At a current density of 600 mA g?1, it maintains a reversible capacity of 780 mAh g?1 for 1200 cycles. Moreover, it retains 50% of the capacity at 60 mA g?1 even when the current density increases to 6 A g?1. The superior electrochemical performance of SeSx/CPAN composite demonstrates that it is a promising cathode material for long cycle life and high power density lithium ion batteries. This is the first report on long cycling stability and high rate capability of selenium sulfide‐based cathode material.  相似文献   

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