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1.
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   

2.
Li‐rich layered metal oxides have attracted much attention for their high energy density but still endure severe capacity fading and voltage decay during cycling, especially at elevated temperature. Here, facile surface treatment of Li1.17Ni0.17Co0.17Mn0.5O2 (0.4Li2MnO3·0.6LiNi1/3Co1/3Mn1/3O2) spherical cathode material is designed to address these drawbacks by hybrid surface protection layers composed of Mg2+ pillar and Li‐Mg‐PO4 layer. As a result, the surface coated Li‐rich cathode material exhibits much enhanced cycling stability at 60 °C, maintaining 72.6% capacity retention (180 mAh g?1) between 3.0 and 4.7 V after 250 cycles. More importantly, 88.7% average discharge voltage retention can be obtained after the rigorous cycle test. The strategy developed here with novel hydrid surface protection effect can provide a vital approach to inhibit the undesired side reactions and structural deterioration of Li‐rich cathode materials and may also be useful for other layered oxides to increase their cycling stability at elevated temperature.  相似文献   

3.
Self‐supporting Sn foil is a promising high‐volumetric‐capacity anode for lithium ion batteries (LIBs), but it suffers from low initial Coulombic efficiency (ICE). Here, mechanical prelithiation is adopted to improve ICE, and it is found that Sn foils with coarser grains are prone to cause electrode damage. To mitigate damage and prepare thinner lithiated electrodes, 3Ag0.5Cu96.5Sn foil is used that has more refined grains (5–10 µm) instead of Sn (50–100 µm), where the abundant grain boundaries (GBs) offer more sliding systems to release stress and reduce deep fractures. Thus, the thickness of Lix3Ag0.5Cu96.5Sn can be reduced to 50 µm, compared to 100 µm LixSn. When the foils contact open air, the Sn‐Li‐O(H) products are more stable than Li‐O(H), thus Lix3Ag0.5Cu96.5Sn shows outstanding air stability. The as‐prepared 50 µm foil anode achieves stable 200 cycles in LiFePO4//Lix3Ag0.5Cu96.5Sn full cell (≈2.65 mAh cm?2) and the capacity retention is 95%. Even at 5C, the capacity of Lix3Ag0.5Cu96.5Sn is still up to ≈1.8 mAh cm?2. The cycle life of NCM523//Lix3Ag0.5Cu96.5Sn full cell exceeds that of NCM523//Li. Furthermore, 70 µm Lix3Ag0.5Cu96.5Sn is used as double‐sided anode for a 3 cm × 2.8 cm pouch cell and its actual volumetric capacity density is 674 mAh cm?3 after 50 cycles.  相似文献   

4.
Lithium‐air (Li‐air) batteries have become attractive because of their extremely high theoretical energy density. However, conventional Li‐air cells operating with non‐aqueous electrolytes suffer from poor cycle life and low practical energy density due to the clogging of the porous air cathode by insoluble discharge products, contamination of the organic electrolyte and lithium metal anode by moist air, and decomposition of the electrolyte during cycling. These difficulties may be overcome by adopting a cell configuration that consists of a lithium‐metal anode protected from air by a Li+‐ion solid electrolyte and an air electrode in an aqueous catholyte. In this type of configuration, a Li+‐ion conducting “buffer” layer between the lithium‐metal anode and the solid electrolyte is often necessary due to the instability of many solid electrolytes in contact with lithium metal. Based on the type of buffer layer, two different battery configurations are possible: “hybrid” Li‐air batteries and “aqueous” Li‐air batteries. The hybrid and aqueous Li‐air batteries utilize the same battery chemistry and face similar challenges that limit the cell performance. Here, an overview of recent developments in hybrid and aqueous Li‐air batteries is provided and the factors that influence their performance and impede their practical applications, followed by future directions are discussed.  相似文献   

5.
Promising lithium–oxygen batteries (LOBs) with extra‐high capacities have attracted increasing attention for use in future electric devices. However, the challenges facing this complicated battery system still limit their practical applications. These challenges mainly consist of inefficient product evolution and low‐activity catalysts. In present work, a cation occupying, modified 3D‐architecture NiFeO cubic spinel is constructed via superassembly strategy to achieve a high rate, stable electrocatalyst for LOBs. The octahedron predominant spinel provides a stable polycrystal structure and optimized electronic structure, which dominates the discharge/charge products evolution with multiformation kinetics of crystal Li2O2 and Li2?xO2 at low and high rate conditions and energetically favors the mass transport between the electrode/electrolyte interface. Simultaneously, the porous NiFeO framework provides adequate spaces for Li2O2 accommodation and complex channels for sufficient electrolyte, oxygen, and ion transportation, which dramatically alter the cathode catalysis for an unprecedented performance. As a consequence, a large specific capacity of 23413 mAh g?1 and an excellent cyclability of 193 cycles at a high current of 1000 mA g?1, and 300 cycles at a current of 500 mA g?1, are achieved. The present work provides intrinsic insights into designing high‐performance metal oxide electrocatalysts for Li–O2 batteries with fine‐tuned electronic and frame structure.  相似文献   

6.
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   

7.
For the lithium (Li) metal anode, constructing a strong and durable protective layer with lithium-ion permeability is crucial, especially in high donor number (DN) solvent system. High DN solvent-based electrolytes can support both higher capacity and lower charge overpotential in the rechargeable lithium–oxygen batteries (LOBs). However, Li anodes in high DN solvent system suffer from severe corrosion and uncontrolled dendrite growth due to the unstable solid-electrolyte interphase (SEI). Typically, this interface is formed in situ through electrochemical processes with complicated component and spatial distribution. Here, a functional molecule is introduced to construct an ion-wall (IW) on Li surface by prechemical sequential reactions (p-CSRs), through which the crystalline nanoparticles as bricks and amorphous hybrid compounds as the mortar can be produced to build such a “wall.” Different from the conventional SEI, this wall is not only compact and uniform, but also possess high strength, excellent passivation properties and high ionic conductivity. With these properties, the IW could suppress Li dendrites and inhabit the side reaction, supporting highly reversible Li plating/stripping behavior in high DN solvent system. As a result, the cycle stability of LOBs based on the IW protected Li anode is significantly improved.  相似文献   

8.
Rational structure design of the current collector along with further engineering of the solid‐electrolyte interphases (SEI) layer is one of the most promising strategies to achieve uniform Li deposition and inhibit uncontrolled growth of Li dendrites. Here, a Li2S layer as an artificial SEI with high compositional uniformity and high lithium ion conductivity is in situ generated on the surface of the 3D porous Cu current collector to regulate homogeneous Li plating/stripping. Both simulations and experiments demonstrate that the Li2S protective layer can passivate the porous Cu skeleton and balance the transport rate of lithium ions and electrons, thereby alleviating the agglomerated Li deposition at the top of the electrode or at the defect area of the SEI layer. As a result, the modified current collector exhibits long‐term cycling of 500 cycles at 1 mA cm?2 and stable electrodeposition capabilities of 4 mAh cm?2 at an ultrahigh current density of 4 mA cm?2. Furthermore, full batteries (LiFePO4 as cathode) paired with this designed 3D anode with only ≈200% extra lithium show superior stability and rate performance than the batteries paired with lithium foil (≈3000% extra lithium). These explorations provide new strategies for developing high‐performance Li metal anodes.  相似文献   

9.
Use of a protective coating on a lithium metal anode (LMA) is an effective approach to enhance its coulombic efficiency and cycling stability. Here, a facile approach to produce uniform silver nanoparticle‐decorated LMA for high‐performance Li metal batteries (LMBs) is reported. This effective treatment can lead to well‐controlled nucleation and the formation of a stable solid electrolyte interphase (SEI). Ag nanoparticles embedded in the surface of Li anodes induce uniform Li plating/stripping morphologies with reduced overpotential. More importantly, cross‐linked lithium fluoride‐rich interphase formed during Ag+ reduction enables a highly stable SEI layer. Based on the Ag‐LiF decorated anodes, LMBs with LiNi1/3Mn1/3Co1/3O2 cathode (≈1.8 mAh cm?2) can retain >80% capacity over 500 cycles. The similar approach can also be used to treat sodium metal anodes. Excellent stability (80% capacity retention in 10 000 cycles) is obtained for a Na||Na3V2(PO4)3 full cell using a Na‐Ag‐NaF/Na anode cycled in carbonate electrolyte. These results clearly indicate that synergetic control of the nucleation and SEI is an efficient approach to stabilize rechargeable metal batteries.  相似文献   

10.
Highly-efficient cathode catalysts are the key to improve high rate cycle stability, avoid side reactions, and lower the overpotential of lithium–oxygen batteries (LOBs). MXenes are predicted to be one of the most impressive materials for energy applications. In this work, the catalytic capability of Nb2C MXene is demonstrated with a uniform O-terminated surface as a cathode material for LOBs. The easily fabricated uniform O-terminated surface, high catalytic activity of Nb2CO2 sites, and unique reaction kinetics contribute to the excellent electrocatalytic performance of Nb2C MXene. The uniform O-terminated surface on Nb2C MXene is obtained after heat treatment. Density functional theory calculations reveal the superior catalytic activity of Nb2CO2 compared to other anchor groups and bare surfaces. The calculations also reveal the multinucleation and growth/decomposition mechanism for discharge products on the Nb2CO2 surface. This mechanism is believed to account for the results characterized by ex situ and in situ measurements. The spatial-direction accumulated porous discharge products at high current density contribute to the excellent high-rate cycle stability. For example, the cathodes exhibit cycle stability for 130 cycles at an ultrahigh current density of 3 A g−1. The present work provides insights into the modulation of catalytic capabilities, and the rational design of high-performance MXenes based electrocatalysts.  相似文献   

11.
Lithium–oxygen batteries are in fact the only rechargeable batteries that can rival internal combustion engines, in terms of high energy density. However, they are still under development due to low‐efficiency and short lifetime issues. There are problems of side reactions on the cathode side, high reactivity of the Li anode with solution species, and consumption of redox mediators via reactions with metallic lithium. Therefore, efforts are made to protect/block the lithium metal anode in these cells, in order to mitigate side reactions. However, new approach is required in order to solve the problems mentioned above, especially the irreversible reactions of the redox mediators which are mandatory to these systems with the Li anode. Here, optimized bicompartment two solution cells are proposed, in which detrimental crossover between the cathode and anode is completely avoided. The Li metal anode is cycled in electrolyte solution containing fluorinated ethylene carbonate, in which its cycling efficiency is excellent. The cathode compartment contains ethereal solution with redox mediator that enables oxidation of Li2O2 at low potentials. The electrodes are separated by a solid electrolyte membrane, allowing free transport of Li ions. This approach increases cycle life of lithium oxygen cells and their energy efficiency.  相似文献   

12.
Li metal, which has a high theoretical specific capacity and low redox potential, is considered to the most promising anode material for next‐generation Li ion‐based batteries. However, it also exhibits a disadvantageous solid electrolyte interphase (SEI) layer problem that needs to be resolved. Herein, an advanced separator composed of reduced graphene oxide fiber attached to aramid paper (rGOF‐A) is introduced. When rGOF‐A is applied, F? anions, generated from the decomposition of the LiPF6 electrolyte during the SEI layer formation process form semi‐ionic C? F bonds along the surface of rGOF. As Li+ ions are plated, the “F‐doped” rGO surface induces the formation of LiF, which is known as a component of a chemically stable SEI, therefore it helps the Li metal anode to operate stably at a high current of 20 mA cm?2 with a high capacity of 20 mAh cm?2. The proposed rGOF‐A separator successfully achieves a stable SEI layer that could resolve the interfacial issues of the Li metal anode.  相似文献   

13.
Nanolayers of Al2O3 and TiO2 coatings were applied to lithium‐ and manganese‐rich cathode powder Li1.2Ni0.13Mn0.54Co0.13O2 using an atomic layer deposition (ALD) method. The ALD coatings exhibited different surface morphologies; the Al2O3 surface film appeared to be uniform and conformal, while the TiO2 layers appeared as particulates across the material surface. In a Li‐cell, the Al2O3 surface film was stable during repeated charge and discharge, and this improved the cell cycling stability, despite a high surface impedance. The TiO2 layer was found to be more reactive with Li and formed a LixTiO2 interface, which led to a slight increase in cell capacity. However, the repetitive insertion/extraction process for the Li+ ions caused erosion of the surface protective TiO2 film, which led to degradation in cell performance, particularly at high temperature. For cells comprised of the coated Li1.2Ni0.13Mn0.54Co0.13O2 and an anode of meso‐carbon‐micro‐beads (MCMB), the cycling stability introduced by ALD was not enough to overcome the electrochemical instability of MCMB graphite. Therefore, protection of the cathode materials by ALD Al2O3 or TiO2 can address some of the capacity fading issues related to the Li‐rich cathode at room temperature.  相似文献   

14.
The development of lithium–sulfur batteries necessitates a thorough understanding of the lithium‐deposition process. A novel full‐cell configuration comprising an Li2S cathode and a bare copper foil on the anode side is presented here. The absence of excess lithium allows for the realization of a truly lithium‐limited Li–S battery, which operates by reversible plating and stripping of lithium on the hostless‐anode substrate (copper foil). Its performance is closely tied to the efficiency of lithium deposition, generating valuable insights on the role and dynamic behavior of lithium anode. The Li2S full cell shows reasonable capacity retention with a Coulombic efficiency of 96% over 100 cycles, which is a tremendous improvement over that of a similar lithium‐plating‐based full cell with LiFePO4 cathodes. The exceptional robustness of the Li2S system is attributed to an intrinsic stabilization of the lithium‐deposition process, which is mediated by polysulfide intermediates that form protective Li2S and Li2S2 regions on the deposited lithium. Combined with the large improvements in energy density and safety by the elimination of a metallic lithium anode, the stability and electrochemical performance of the lithium‐plating‐based Li2S full cell establish it as an important trajectory for Li–S battery research, focusing on practical realization of reversible lithium anodes.  相似文献   

15.
The Li‐rich cathode materials have been considered as one of the most promising cathodes for high energy Li‐ion batteries. However, realization of these materials for use in Li‐ion batteries is currently limited by their intrinsic problems. To overcome this barrier, a new surface treatment concept is proposed in which a hybrid surface layer composed of a reduced graphene oxide (rGO) coating and a chemically activated layer is created. A few layers of GO are first coated on the surface of the Li‐rich cathode material, followed by a hydrazine treatment to produce the reducing agent of GO and the chemical activator of the Li2MnO3 phase. Compared to previous studies, this surface treatment provides substantially improved electrochemical performance in terms of initial Coulombic effiency and retention of discharge voltage. As a result, the surface‐treated 0.4Li­2MnO3–0.6LiNi1/3Co1/3Mn1/3O2 exhibits a high capacity efficiency of 99.5% during the first cycle a the discharge capacity of 250 mAh g?1 (2.0–4.6 V under 0.1C), 94.6% discharge voltage retention during 100 cycles (1C) and the superior capacity retention of 60% at 12C at 24 °C.  相似文献   

16.
Lithium–sulfur (Li–S) batteries are a very appealing power source with extremely high energy density. But the use of a metallic‐Li anode causes serious safety hazards, such as short‐circuiting and explosion of the cells. Replacing a sulfur cathode with a fully‐lithiated lithium sulfide (Li2S) to pair with metallic‐Li‐free high‐capacity anodes paves a feasible way to address this issue. However, the practical utility of Li2S cathodes faces the challenges of poor conductivity, sluggish activation process, and high sensitivity to moisture and oxygen that make electrode production more difficult than dealing with sulfur cathodes. Here, an efficient but low‐cost strategy for easy production of freestanding flexible Li2S‐based paper electrodes with very high mass and capacity loading in terms of in situ carbonthermal reduction of Li2SO4 by electrospinning carbon is reported. This chemistry enables high loading but strong affinity of ultrafine Li2S nanoparticles in a freestanding conductive carbon‐nanofiber network, meanwhile greatly reducing the manufacturing complexity and cost of Li2S cathodes. Benefiting from enhanced structural stability and reaction kinetics, the areal specific capacities of such cathodes can be significantly boosted with less sacrificing of high‐rate and cycling capability. This unique Li2S‐cathode design can be directly applied for constructing metallic‐Li‐free or flexible Li–S batteries with high‐energy density.  相似文献   

17.
There is a growing concern about the cyclability and safety, in particular, of the high‐energy density lithium–metal batteries. This concern is even greater for Li–O2 batteries because O2 that is transported from the cathode to the anode compartment, can exacerbate side reactions and dendrite growth of the lithium metal anode. The key to solving this dilemma lays in tailoring the solid electrolyte interphase (SEI) formed on the lithium metal anode in Li–O2 batteries. Here it is reported that a new electrolyte, formed from LiFSI as the salt and a mixture of tetraethylene glycol dimethyl ether and polymeric ionic liquid of P[C5O2NMA,11]FSI as the solvent, can produce a stable electrode (both cathode and anode)|electrolyte interface in Li–O2 batteries. Specifically, this new electrolyte, when in contact with lithium metal anodes, has the ability to produce a uniform SEI with high ionic conductivity for Li+ transport and desired mechanical property for suppression of dendritic lithium growth. Moreover, the electrolyte possesses a high oxidation tolerance that is very beneficial to the oxygen electrochemistry on the cathode of Li–O2 batteries. As a result, enhanced reversibility and cycle life are realized for the resultant Li–O2 batteries.  相似文献   

18.
Although the “water‐in‐salt” electrolyte has significantly expanded the electrochemical stability window of aqueous electrolytes from 1.23 to 3 V, its inevitable hydrogen evolution under 1.9 V versus Li+/Li prevents the practical use of many energy‐dense anodes. Meanwhile, its liquidus temperature at 17 °C restricts its application below ambient temperatures. An advanced hybrid electrolyte is proposed in this work by introducing acetonitrile (AN) as co‐solvent, which minimizes the presence of interfacial water at the negatively charged electrode surface, and generates a thin and uniform interphase consisting of an organic outer layer based on nitrile (C?N) and sulfamide (R‐S‐N‐S) species and an inner layer rich in LiF. Such an interphase significantly suppresses water reduction and expands the electrochemical stability window to an unprecedented width of 4.5 V. Thanks to the low freezing point (?48 °C) and low viscosity of AN, the hybrid electrolyte is highly conductive in a wide temperature range, and enables a LiMn2O4/Li4Ti5O12 full cell at both ambient and sub‐ambient temperatures with excellent cycling stability and rate capability. Meanwhile, such a hybrid electrolyte also inherits the nonflammable nature of aqueous electrolyte. The well‐balanced merits of the developed electrolyte make it suitable for high energy density aqueous batteries.  相似文献   

19.
With high theoretical energy density, rechargeable metal–gas batteries (e.g., Li–CO2 battery) are considered as one of the most promising energy storage devices. However, their practical applications are hindered by the sluggish reaction kinetics and discharge product accumulation during battery cycling. Currently, the solutions focus on exploration of new catalysts while the thorough understanding of their underlying mechanisms is often ignored. Herein, the interfacial electronic interaction within rationally designed catalysts, ZnS quantum dots/nitrogen‐doped reduced graphene oxide (ZnS QDs/N‐rGO) heterostructures, and their effects on transformation and deposition of discharge products in the Li–CO2 battery are revealed. In this work, the interfacial interaction can both enhance the catalytic activities of ZnS QDs/N‐rGO heterostructures and induce the nucleation of discharge products to form a homogeneous Li2CO3/C film with excellent electronic transmission and high electrochemical activities. When the batteries cycle within a cutoff specific capacity of 1000 mAh g?1 at a current density of 400 mA g?1, the cycling performance of the Li–CO2 battery using a ZnS QDs/N‐rGO cathode is over 3 and 9 times than those coupled with a ZnS nanosheets (NST)/N‐rGO cathode and a N‐rGO cathode, respectively. This work provides comprehensive understandings on designing catalysts for Li–CO2 batteries as well as other rechargeable metal–gas batteries.  相似文献   

20.
The Li–O2 battery (LOB) represents a promising candidate for future electric vehicles owing to its outstanding energy density. However, the practical application of LOB cells is largely blocked by the poor cycling performance of cathode materials. Herein, an ultralong 440‐cycle life of an LOB cell is achieved using CeO2 nanocubes super‐assembled on an inverse opal carbon matrix as the cathode material without any additives. CeO2 is proved to be effective for the complete and sensitive decomposition of loosely stacked Li2O2 films during the oxygen evolution reaction process and full accommodation of volume changes caused by the fast growth of Li2O2 films during the oxygen reduction reaction process. The super‐assembled porous CeO2/C frameworks satisfy critical requirements including controlled size, morphology, high Ce3+/Ce4+ ratio, and efficient volume change accommodation, which dramatically increase the cycle life of LOB cell to 440 cycles. This study reveals the design strategy for high performance CeO2 catalyst cathodes for LOB cells and the generation mechanisms of Li2O2 films during the discharge process by using density functional theory calculations, showing new avenues for improving the future smart design of CeO2‐based cathode catalysts for Li–O2 batteries.  相似文献   

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