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1.
The interrelation is explored between external pressure (0.1, 1, and 10 MPa), solid electrolyte interphase (SEI) structure/morphology, and lithium metal plating/stripping behavior. To simulate anode-free lithium metal batteries (AF-LMBs) analysis is performed on “empty” Cu current collectors in standard carbonate electrolyte. Lower pressure promotes organic-rich SEI and macroscopically heterogeneous, filament-like Li electrodeposits interspersed with pores. Higher pressure promotes inorganic F-rich SEI with more uniform and denser Li film. A “seeding layer” of lithiated pristine graphene (pG@Cu) favors an anion-derived F-rich SEI and promotes uniform metal electrodeposition, enabling extended electrochemical stability at a lower pressure. State-of-the-art electrochemical performance is achieved at 1MPa: pG-enabled half-cell is stable after 300 h (50 cycles) at 1 mA cm−2 rate −3 mAh cm−2 capacity (17.5 µm plated/stripped), with cycling Coulombic efficiency (CE) of 99.8%. AF-LMB cells with high mass loading NMC622 cathode (21 mg cm−2) undergo 200 cycles with a CE of 99.4% at C/5-charge and C/2-discharge (1C = 178 mAh g−1). Density functional theory (DFT) highlights the differences in the adsorption energy of solvated-Li+ onto various crystal planes of Cu (100), (110), and (111), versus lithiated/delithiated (0001) graphene, giving insight regarding the role of support surface energetics in promoting SEI heterogeneity.  相似文献   

2.
Li2S is a fully lithiated sulfur‐based cathode with a high theoretical capacity of 1166 mAh g?1 that can be coupled with lithium‐free anodes to develop high‐energy‐density lithium–sulfur batteries. Although various approaches have been pursued to obtain a high‐performance Li2S cathode, there are still formidable challenges with it (e.g., low conductivity, high overpotential, and irreversible polysulfide diffusion) and associated fabrication processes (e.g., insufficient Li2S, excess electrolyte, and low reversible capacity), which have prevented the realization of high electrochemical utilization and stability. Here, a new cathode design composed of a homogeneous Li2S‐TiS2‐electrolyte composite that is prepared by a simple two‐step dry/wet‐mixing process is demonstrated, allowing the liquid electrolyte to wet the powder mixture consisting of insulating Li2S and conductive TiS2. The close‐contact, three‐phase boundary of this system improves the Li2S‐activation efficiency and provides fast redox‐reaction kinetics, enabling the Li2S‐TiS2‐electrolyte cathode to attain stable cyclability at C/7 to C/3 rates, superior long‐term cyclability over 500 cycles, and promising high‐rate performance up to 1C rate. More importantly, this improved performance results from a cell design attaining a high Li2S loading of 6 mg cm?2, a high Li2S content of 75 wt%, and a low electrolyte/Li2S ratio of 6.  相似文献   

3.
Development of sulfur cathodes with 100% coulombic efficiency (CE) and good cycle stability remains challenging due to the polysulfide dissolution in electrolytes. Here, it is demonstrated that electrochemical reduction of lithium bis(fluorosulfonyl)imide (LiFSI) based electrolytes at a potential close to the sulfur cathode operation forms in situ protective coating on both cathode and anode surfaces. Quantum chemistry studies suggest the coating formation is initiated by the FSI(‐F) anion radicals generated during electrolyte reduction. Such a reduction additionally results in the formation of LiF. Accelerated cycle stability tests at 60 °C in a very simple electrolyte (LiFSI in dimethoxyethane with no additives) show an average CE approaching 100.0% over 1000 cycles with a capacity decay less than 0.013% per cycle after stabilization. Such a remarkable performance suggests a great promise of both an in situ formation of protective solid electrolyte coatings to avoid unwanted side reactions and the use of a LiFSI salt for this purpose.  相似文献   

4.
Lithium–metal fluoride batteries promise significantly higher energy density than the state‐of‐the‐art lithium‐ion batteries and lithium–sulfur batteries. Unfortunately, commercialization of metal fluoride cathodes is prevented by their high resistance, irreversible structural change, and rapid degradation. In this study, a substantial boost in metal fluoride (MF) cathode stability by designing nanostructure with two layers of protective shells—one deposited ex situ and the other in situ is demonstrated. Such methodology achieves over 90% capacity retention after 300 charge–discharge cycles, producing the first report on FeF3 as a cathode material, where a very high capacity utilization in combination with excellent stability is approaching the level needed for practical applications of FeF3. The cathode solid electrolyte interphase (CEI) containing lithium oxalate and B? F bond containing anions is found to effectively protect the cathode material from direct contact with electrolytes, thus greatly suppressing the dissolution of Fe. Quantum chemistry and molecular dynamics calculations provide unique insights into the mechanisms of CEI layer formation. As a result, this work not only demonstrates unprecedented performance, but also provides the reader with a better fundamental understanding of electrochemical behavior of MF cathodes and the positive impact observed with the application of a lithium bis(oxalato)borate salt in the electrolyte.  相似文献   

5.
All‐solid‐state batteries are promising candidates for the next‐generation safer batteries. However, a number of obstacles have limited the practical application of all‐solid‐state Li batteries (ASSLBs), such as moderate ionic conductivity at room temperature. Here, unlike most of the previous approaches, superior performances of ASSLBs are achieved by greatly reducing the thickness of the solid‐state electrolyte (SSE), where ionic conductivity is no longer a limiting factor. The ultrathin SSE (7.5 µm) is developed by integrating the low‐cost polyethylene separator with polyethylene oxide (PEO)/Li‐salt (PPL). The ultrathin PPL shortens Li+ diffusion time and distance within the electrolyte, and provides sufficient Li+ conductance for batteries to operate at room temperature. The robust yet flexible polyethylene offers mechanical support for the soft PEO/Li‐salt, effectively preventing short‐circuits even under mechanical deformation. Various ASSLBs with PPL electrolyte show superior electrochemical performance. An initial capacity of 135 mAh g?1 at room temperature and the high‐rate capacity up to 10 C at 60 °C can be achieved in LiFePO4/PPL/Li batteries. The high‐energy‐density sulfur cathode and MoS2 anode employing PPL electrolyte also realize remarkable performance. Moreover, the ASSLB can be assembled by a facile process, which can be easily scaled up to mass production.  相似文献   

6.
Severe polysulfide dissolution and shuttling are the main challenges that plague the long cycle life and capacity retention of lithium-sulfur (Li-S) batteries. To address these challenges, efficient separators are designed and modified with a dual functional bimetallic metal-organic framework (MOF). Flower-shaped bimetallic MOFs (i.e., Fe-ZIF-8) with nanostructured pores are synthesized at 35 °C in water by introducing dopant metal sites (Fe), which are then coated on a polypropylene (PP) separator to provide selective channels, thereby effectively inhibiting the migration of lithium polysulfides while allowing homogeneous transport of Li-ions. The active sites of the Fe-ZIF-8 enable electrocatalytic conversion, facilitating the conversion of lithium polysulfides. Moreover, the developed separator can prevent dendrite formation due to the uniform pore size and hence the even Li-ion transport and deposition. A coin cell using a Fe-ZIF-8/PP separator with S-loaded carbon cathode displayed a high cycle life of 1000 cycles with a high initial discharge capacity of 863 mAh g−1 at 0.5 C and a discharge capacity of 746 mAh g−1 at a high rate of 3 C. Promising specific capacity has been documented even under high sulfur loading of 5.0 mg cm−2 and electrolyte to the sulfur ratio (E/S) of 5 µL mg−1.  相似文献   

7.
Various electrolyte additives are developed to construct a cathode electrolyte interphase (CEI) layer for high-voltage LiCoO2 since the cathode suffers severe interfacial degradation when increasing the cut-off voltage over 4.55 V. However, the CEI derived from the additive sacrificial reaction faces the risk of rupture due to the corrosion reaction and the volumetric variation of the cathode. Herein, a non-passivating cathode interface is realized for 4.6 V LiCoO2 with a non-sacrificial electrolyte additive (TBAClO4) by regulating the solvent environment at the interface rather than the preferential decomposition for CEI formation. Owing to the novel protection mechanism, the cell performance shows little dependence on the CEI-formation process. Therefore, an ultra-high initial coulombic efficiency (96.63%) and excellent cycling stability (81% capacity retention after 300 cycles) are achieved in Li||LiCoO2 batteries. Moreover, even with the electrolyte containing 1000 ppm H2O, the remarkable water capture ability of the additive together with its interfacial regulation enables the 4.6 V Li||LiCoO2 battery to retain 80% capacity after 200 cycles. This non-sacrificial strategy provides new insights into high-voltage electrolyte additive design for high-energy-density lithium metal batteries.  相似文献   

8.
A comprehensive approach is reported to construct stable and high volumetric energy density lithium–sulfur batteries, by coupling a multifunctional and hierarchically structured sulfur composite with an in‐situ cross‐linked binder. Through a combination of first‐principles calculations and experimental studies, it is demonstrated that a hybrid sulfur host composed by alternately stacking graphene and layered graphitic carbon nitride embraces high electronic conductivity as well as high polysulfide adsorptivity. It is further shown that the cross‐linked elastomeric binder empowers the hierarchical sulfur composites—multi‐microns in size—with the ability to form crack‐free and compact high‐loading electrodes using traditional slurry processing. Using this approach, electrodes with up to 14.9 mg cm?2 sulfur loading and an extremely low electrolyte/sulfur ratio as low as 3.5: 1 µL mg?1 are obtained. This study sheds light on the essential role of multifaceted cathode design and further on the challenges facing lithium metal anodes in building high volumetric energy density lithium–sulfur batteries.  相似文献   

9.
Safety and the polysulfide shuttle reaction are two major challenges for liquid electrolyte lithium–sulfur (Li–S) batteries. Although use of solid‐state electrolytes can overcome these two challenges, it also brings new challenges by increasing the interface resistance and stress/strain. In this work, the interface resistance and stress/strain of sulfur cathodes are significantly reduced by conformal coating ≈2 nm sulfur (S) onto reduced graphene oxide (rGO). An Li–S full cell consisting of an rGO@S‐Li10GeP2S12‐acetylene black (AB) composite cathode is evaluated. At 60 °C, the all‐solid‐state Li–S cell demonstrates a similar electrochemical performance as in liquid organic electrolyte, with high rate capacities of 1525.6, 1384.5, 1336.3, 903.2, 502.6, and 204.7 mA h g?1 at 0.05, 0.1, 0.5, 1.0, 2.0, and 5.0 C, respectively. It can maintain a high and reversible capacity of 830 mA h g?1 at 1.0 C for 750 cycles. The uniform distribution of the rGO@S nanocomposite in the Li10GeP2S12‐AB matrix generates uniform volume changes during lithiation/delithiation, significantly reducing the stress/strain, thus extending the cycle life. Minimization of the stress/strain of solid cells is the key for a long cycle life of all‐solid‐state Li–S batteries.  相似文献   

10.
Minimizing electrolyte use is essential to achieve high practical energy density of lithium–sulfur (Li–S) batteries. However, the sulfur cathode is more readily passivated under a lean electrolyte condition, resulting in low sulfur utilization. In addition, continuous electrolyte decomposition on the Li metal anode aggravates the problem, provoking rapid capacity decay. In this work, the dual functionalities of NO3? as a high‐donor‐number (DN) salt anion is presented, which improves the sulfur utilization and cycling stability of lean‐electrolyte Li–S batteries. The NO3? anion elevates the solubility of the sulfur species based on its high electron donating ability, achieving a high sulfur utilization of above 1200 mA h g?1. Furthermore, the anion suppresses electrolyte decomposition on the Li metal by regulating the lithium ion (Li+) solvation sheath, enhancing the cycle performance of the lean electrolyte cell. By understanding the anionic effects, this work demonstrates the potential of the high‐DN electrolyte, which is beneficial for both the cathode and anode of Li–S batteries.  相似文献   

11.
Nanostructured V2O5 is emerging as a new cathode material for lithium ion batteries for its distinctly high theoretic capacity over the current commercial cathodes. The main challenges associated with nanostructured V2O5 cathodes are structural degradation, instability of the solid‐electrolyte interface layer, and poor electron conductance, which lead to low capacity and rapid decay of cyclic stability. Here, a novel composite structure of V2O5 nanoparticles encapsulated in 3D networked porous carbon matrix coated on carbon fibers (V2O5/3DC‐CFs) is reported that effectively addresses the mentioned problems. Remarkably, the V2O5/3DC‐CF electrode exhibits excellent overall lithium‐storage performance, including high Coulombic efficiency, excellent specific capacity, outstanding cycling stability and rate property. A reversible capacity of ≈183 mA h g?1 is obtained at a high current density of 10 C, and the battery retains 185 mA h g?1 after 5000 cycles, which shows the best cycling stability reported to date among all reported cathodes of lithium ion batteries as per the knowledge. The outstanding overall properties of the V2O5/3DC‐CF composite make it a promising cathode material of lithium ion batteries for the power‐intensive energy storage applications.  相似文献   

12.
Rechargeable metal–sulfur batteries encounter severe safety hazards and fast capacity decay, caused by the flammable and shrinkable separator and unwanted polysulfide dissolution under elevated temperatures. Herein, a multifunctional Janus separator is designed by integrating temperature endurable electrospinning polyimide nonwovens with a copper nanowire‐graphene nanosheet functional layer and a rigid lithium lanthanum zirconium oxide‐polyethylene oxide matrix. Such architecture offers multifold advantages: i) intrinsically high dimensional stability and flame‐retardant capability, ii) excellent electrolyte wettability and effective metal dendritic growth inhibition, and iii) powerful physical blockage/chemical anchoring capability for the shuttled polysulfides. As a consequence, the as constructed lithium–sulfur battery using a pure sulfur cathode displays an outstandingly high discharge capacity of 1402.1 mAh g?1 and a record high cycling stability (approximately average 0.24% capacity decay per cycle within 300 cycles) at 80 °C, outperforming the state‐of‐the‐art results in the literature. Promisingly, a high sulfur mass loading of ≈3.0 mg cm?2 and a record low electrolyte/sulfur ratio of 6.0 are achieved. This functional separator also performs well for a high temperature magnesium–sulfur battery. This work demonstrates a new concept for high performance metal–sulfur battery design and promises safe and durable operation of the next generation energy storage systems.  相似文献   

13.
The rapid growth of lithium dendrites has seriously hindered the development and practical application of high-energy-density all-solid-state lithium metal batteries (ASSLMBs). Herein, a soft carbon (SC)-nano Li6.4La3Zr1.4Ta0.6O12 (LLZTO) (with high ionic conductivity and diffusion coefficient) mixed ionic and electronic conducting interface layer is designed to promote the rapid migration of Li+ at the interfacial layer, induce the uniform deposition of lithium metal on nanoscale (nano) LLZTO ion-conducting network inside the interface layer, effectively suppress the growth of lithium dendrites, and significantly improve the electrochemical performance of ASSLMBs. LiZrO2@LiCoO2(LZO@LCO)/Li6PS5Cl(LPSCl)-nano LLZTO/Li ASSLMB achieves high current density (12.5 mA cm−2), ultra-high areal capacity (15 mAh cm−2, corresponding to LZO@LCO mass loadings of 111.11 mg cm−2), and ultra-long cycle life (20 000 cycles). Therefore, the introduction of SC-nano LLZTO mixed conducting interface layer can greatly improve the interfacial stability between solid-state electrolyte (SSE) and lithium metal anode to enable dendrite-free ASSLMBs.  相似文献   

14.
Li metal can potentially deliver much higher specific capacity than commercially used anodes. Nevertheless, because of its poor reversibility, abundant excess Li (usually more than three times) is required in Li metal batteries, leading to higher costs and decreased energy density. Here, a concentrated lithium bis(trifluoromethane sulfonyl) imide (LiTFSI)–lithium nitrate (LiNO3)–lithium bis(fluorosulfonyl)imide (LiFSI) ternary‐salts electrolyte is introduced to realize a high stable Li metal full‐cell with only a slight excess of Li. LiNO3 and LiFSI contribute to the formation of stable Li2O–LiF‐rich solid electrolyte interface layers, and LiTFSI helps to stabilize the electrolyte under high concentration. Li metal in the electrolyte remains stable over 450 cycles and the average Coulombic efficiency reaches 99.1%. Moreover, with 0.5 × excess Li metal, the Coulombic efficiency of Li metal in the LiTFSI–LiNO3–LiFSI reaches 99.4%. The electrolyte also presents high stability to the LiFePO4 cathode, the capacity retention after 500 cycles is 92.0% and the Coulombic efficiency is 99.8%. A Li metal full‐cell with only 0.44 × excess Li is also assembled, it remains stable over 70 cycles and 83% of the initial capacity is maintained after 100 cycles.  相似文献   

15.
The lithium (Li) metal battery (LMB) is one of the most promising candidates for next‐generation energy storage systems. However, it is still a significant challenge to operate LMBs with high voltage cathodes under high rate conditions. In this work, an LMB using a nickel‐rich layered cathode of LiNi0.76Mn0.14Co0.10O2 (NMC76) and an optimized electrolyte [0.6 m lithium bis(trifluoromethanesulfonyl)imide + 0.4 m lithium bis(oxalato)borate + 0.05 m LiPF6 dissolved in ethylene carbonate and ethyl methyl carbonate (4:6 by weight)] demonstrates excellent stability at a high charge cutoff voltage of 4.5 V. Remarkably, these Li||NMC76 cells can deliver a high discharge capacity of >220 mA h g?1 (846 W h kg?1) and retain more than 80% capacity after 1000 cycles at high charge/discharge current rates of 2C/2C (1C = 200 mA g?1). This excellent electrochemical performance can be attributed to the greatly enhanced structural/interfacial stability of both the Ni‐rich NMC76 cathode material and the Li metal anode using the optimized electrolyte.  相似文献   

16.
The practical viability of Li–S cells depends on achieving high electrochemical utilization of sulfur under realistic conditions, such as high sulfur loading and low electrolyte/sulfur (E/S) ratio. Here, metallic 2D 1T′‐ReS2 nanosheets in situ grown on 1D carbon nanotubes (ReS2@CNT) via a facile hydrothermal reaction are presented to efficiently suppress the “polysulfide shuttle” and promote lithium polysulfide (LiPS) redox reactions. The designed ReS2@CNT nanoarchitecture with high conductivity and rich nanoporosity not only facilitates electron transfer and ion diffusion, but also possesses abundant active sites providing high catalytic activity for efficient LiPS conversion. Li–S cells fabricated with ReS2@CNT exhibit high capacity with superior long‐term cyclability with a capacity retention of 71.7% over 1000 cycles even at a high current density of 1C (1675 mA g?1). Also, pouch cells fabricated with the ReS2@CNT/S cathode maintain a low capacity fade rate of 0.22% per cycle. Furthermore, the electrocatalysis mechanism is revealed based on electrochemical studies, theoretical calculations, and in situ Raman spectroscopy.  相似文献   

17.
A novel combination of hard carbon anode sodium pre‐loading and a tailored electrolyte is used to prepare room temperature sodium‐sulfur full cell batteries. The electrochemical loading with sodium ions is realized in a specific mixture of diethyl carbonate, ethylene carbonate, and fluoroethylene carbonate electrolyte in order to create a first solid electrolyte interface (SEI) on the anode surface. Combining such anodes with a porous carbon/sulfur composite cathode results in full cells with a significantly decreased polysulfide shuttle when compared to half cells combined with metallic sodium anodes. Further optimization involves the use of Na2S/P2S5 doped tetraethylene glycol dimethyl ether based electrolyte in the full cell for the formation of a second SEI, reducing polysulfide shuttle even further. More importantly, the electrochemical discharge processes in the cell are improved by adding this dissolved complexation agent to the electrolyte. As a result of this combination sodium‐sulfur cells with tailored cathode materials and electrolytes can achieve high discharge capacities up to 980 mAh g?1sulfur and 1000 cycles with 200 mAh g?1sulfur remaining capacity, at room temperature.  相似文献   

18.
A NaSICON‐type Li+‐ion conductive membrane with a formula of Li1+ x Y x Zr2? x (PO4)3 (LYZP) (x = 0–0.15) has been explored as a solid‐electrolyte/separator to suppress polysulfide‐crossover in lithium‐sulfur (Li‐S) batteries. The LYZP membrane with a reasonable Li+‐ion conductivity shows both favorable chemical compatibility with the lithium polysulfide species and exhibits good electrochemical stability under the operating conditions of the Li‐S batteries. Through an integration of the LYZP solid electrolyte with the liquid electrolyte, the hybrid Li‐S batteries show greatly enhanced cyclability in contrast to the conventional Li‐S batteries with the porous polymer (e.g., Celgard) separator. At a rate of C/5, the hybrid Li ||LYZP|| Li2S6 batteries developed in this study (with a Li‐metal anode, a liquid/LYZP hybrid electrolyte, and a dissolved lithium polysulfide cathode) delivers an initial discharge capacity of ≈1000 mA h g?1 (based on the active sulfur material) and retains ≈90% of the initial capacity after 150 cycles with a low capacity fade‐rate of <0.07% per cycle.  相似文献   

19.
A bifunctional hybrid electrolyte composed of mesoporous silica nanosheets and liquid electrolyte is achieved for lithium–sulfur (Li–S) batteries. This hybrid electrolyte possesses abundant mesopores (2.8 nm), thin feature (20 µm), and high ionic conductivity (1.17 × 10?1 mS cm?1) as well as a low interfacial resistance with electrodes. Such unique features not only enable the efficient inhibition of the growth of lithium dendrites, but also significantly prevents polysulfide shuttling. Consequently, a Li–S battery with this hybrid electrolyte exhibits a relatively high reversible capacity and good capacity retention.  相似文献   

20.
The insulating nature of sulfur, polysulfide shuttle effect, and lithium‐metal deterioration cause a decrease in practical energy density and fast capacity fade in lithium‐sulfur (Li‐S) batteries. This study presents an integrated strategy for the development of hybrid Li‐S batteries based on a gel sulfur cathode, a solid electrolyte, and a protective anolyte composed of a highly concentrated salt electrolyte containing mixed additives. The dense solid electrolyte completely blocks polysulfide diffusion, and also makes it possible to investigate the cathode and anode independently. This gel cathode effectively traps the polysulfide active material while maintaining a low electrolyte to sulfur ratio of 5.2 mL g?1. The anolyte effectively protects the Li metal and suppresses the consumption of liquid electrolyte, enabling stable long‐term cycling for over 700 h in Li symmetric cells. This advanced design can simultaneously suppress the polysulfide shuttle, protect Li metal, and reduce the liquid electrolyte usage. The assembled hybrid batteries exhibit remarkably stable cycling performance over 300 cycles with high capacity. Finally, surface‐sensitive techniques are carried out to directly visualize and probe the interphase formed on the surface of the Li1.5Al0.5Ge1.5(PO4)3 (LAGP) pellet, which may help stabilize the solid–liquid interface.  相似文献   

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