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1.
Constructing artificial solid‐electrolyte interphase (SEI) on the surface of Li metal is an effective approach to improve ionic conductivity of surface SEI and buffer Li dendrite growth of Li metal anode. However, constructing of homogenous ideal artificial SEI is still a great challenge. Here, a mixed lithium‐ion conductive Li2S/Li2Se (denoted as LSSe) protection layer, fabricated by a facile and inexpensive gas–solid reaction, is employed to construct stable surface SEI with high ionic conductivity. The Li2S/Li2Se‐protected Li metal (denoted as LSSe@Li) exhibits a stable dendrite‐free cycling behavior over 900 h with a high lithium stripping/plating capacity of 3 mAh cm?2 at 1.5 mA cm?2 in the symmetrical cell. Compared to bare Li anode, full batteries paired with LiFePO4, sulfur/carbon, and LiNi0.6Co0.2Mn0.2O2 cathodes all present better battery cycling and rate performance when LSSe@Li anode is used. Moreover, Li2Se exhibits a lower lithium‐ion migration energy barrier in comparison with Li2S which is proved by density functional theory calculation.  相似文献   

2.
Anode-free batteries can maximize the energy density but their development is hindered by a lack of Li-rich cathodes for compensating the irreversible Li loss. Li2S cathode is particularly appealing to this desire due to 2.6–4.7 folds more Li content and 4.2–6.8 times higher capacity than conventional intercalation cathodes. But its practical application is hindered by poor stability against moisture attacking in the air. Herein, a facile expendable polymer sheathing strategy toward air-stable Li2S cathodes with high capacities for developing high-performance quasi-solid-state anode-free batteries without risk of cell leakage is reported. Tight protection by dense polymer barrier dramatically prolongs the lifetime of Li2S cathode by 2,000 times at least in the air. Such air-stable Li2S cathode allows for high compatibility of anode-free battery production with commercial schemes. More attractively, the polymer protective layer can in situ transform to multifunctional gel polymer electrolyte for releasing ionic pathways and enhancing cell performance by inhibiting LiPS loss and smoothing Li plating. With air-stable Li2S cathode, the quasi-solid-state anode-free cells are assembled in ambient environment to deliver superb volumetric energy density of 1093 Wh L−1. This study may shed new light to push the commercialization of high-energy and reliable anode-free batteries forward.  相似文献   

3.
Rechargeable Li batteries based on group VIA element cathodes, such as tellurium, are emerging due to their capability to provide equivalent theoretical volumetric capacity density to O and S, as well as an improved activity to react with Li. Herein, bifunctional and elastic carbon nanotube (CNT) aerogel is fabricated to combine with Te nanowires, yielding two types of binder/collector‐free Te cathodes to assemble Li‐Te batteries. The CNTs with high electronic conductivity and hollow porous structure enable stable electric contact and fast transportation of Li+, while trapping Te and Li2Te in its network, triggering fast and stable Li‐Te electrochemistry. Both cathodes are also provided with fine compressibility, helping to buffer their volume changes during lithiation/delithiation and improving electrode integrity. Both cathodes deliver high specific capacity, fine cycling stability, and favorable high‐rate capability, proving their competence in building high‐energy rechargeable Li‐ion batteries.  相似文献   

4.
Lithium sulfide (Li2S) has attracted increasing attention as a promising cathode because of its compatibility with more practical lithium‐free anode materials and its high specific capacity. However, it is still a challenge to develop Li2S cathodes with low electrochemical overpotential, high capacity and reversibility, and good rate performance. This work designs and fabricates a practical Li2S cathode composed of Li2S/few‐walled carbon nanotubes@reduced graphene oxide nanobundle forest (Li2S/FWNTs@rGO NBF). Hierarchical nanostructures are obtained by annealing the Li2SO4/FWNTs@GO NBF, which is prepared by a facile and scalable solution‐based self‐assembly method. Systematic characterizations reveal that in this unique NBF nanostructure, FWNTs act as axial shafts to direct the structure, Li2S serves as the internal active material, and GO sheets provide an external coating to minimize the direct contact of Li2S with the electrolyte. When used as a cathode, the Li2S/FWNTs@rGO NBF achieve a high capacity of 868 mAh g?1Li2S at 0.2C after 300 cycles and an outstanding rate performance of 433 mAh g?1Li2S even at 10C, suggesting that this Li2S cathode is a promising candidate for ultrafast charge/discharge applications. The design and synthetic strategies outlined here can be readily applied to the processing of other novel functional materials to obtain a much wider range of applications.  相似文献   

5.
Despite the unparalleled theoretical gravimetric energy, Li‐O2 batteries are still under a research stage because of their insufficient cycle lives. While the reversibility in air‐cathodes has been lately improved significantly by the deepened understanding on the electrode–electrolyte reaction and the integration of diverse catalysts, the stability of the Li metal interface has received relatively much less attention. The destabilization of the Li metal interface by crossover of water and oxygen from the air‐cathode side can indeed cause as fatal degradation for the cycle life as the irreversibility of the air‐cathodes. Here, it is reported that cheap poreless polyurethane separator can effectively suppress this crossover while allowing Li ions to diffuse through selectively. The polyurethane separator also protects Li metal anodes from redox mediators used for enhancing the reversibility of the air‐cathode reaction. Based on the Li metal protection, a persistent capacity of 600 mAh g?1 is preserved for more than 200 cycles. The current approach can be readily applicable to many other rechargeable batteries that suffer from similar interfacial degradation by side products from the other electrode.  相似文献   

6.
The use of sulfur in the next generation Li‐ion batteries is currently precluded by its poor cycling stability caused by irreversible Li2S formation and the dissolution of soluble polysulfides in organic electrolytes that leads to parasitic cell reactions. Here, a new C/S cathode material comprising short‐chain sulfur species (predominately S2) confined in carbonaceous subnanometer and the unique charge mechanism for the subnano‐entrapped S2 cathodes are reported. The first charge–discharge cycle of the C/S cathode in the carbonate electrolyte forms a new type of thiocarbonate‐like solid electrolyte interphase (SEI). The SEI coated C/S cathode stably delivers ≈600 mAh g?1 capacity over 4020 cycles (0.0014% loss cycle?1) at ≈100% Coulombic efficiency. Extensive X‐ray photoelectron spectroscopy analysis of the discharged cathodes shows a new type of S2 species and a new carbide‐like species simultaneously, and both peaks disappear upon charging. These data suggest a new sulfur redox mechanism involving a separated Li+/S2? ion couple that precludes Li2S compound formation and prevents the dissolution of soluble sulfur anions. This new charge/discharge process leads to remarkable cycling stability and reversibility.  相似文献   

7.
Aprotic Li–O2 batteries are promising candidates for next‐generation energy storage technologies owing to their high theoretical energy densities. However, their practically achievable specific energy is largely limited by the need for porous conducting matrices as cathode support and the passivation of cathode surface by the insulating Li2O2 product. Herein, a self‐standing and hierarchically porous carbon framework is reported with Co nanoparticles embedded within developed by 3D‐printing of cobalt‐based metal–organic framework (Co‐MOF) using an extrusion‐based printer, followed by appropriate annealing. The novel self‐standing framework possesses good conductivity and necessary mechanical stability, so that it can act as a porous conducting matrix. Moreover, the porous framework consists of abundant micrometer‐sized pores formed between Co‐MOF‐derived carbon flakes and meso‐ and micropores formed within the flakes, which together significantly benefit the efficient deposition of Li2O2 particles and facilitate their decomposition due to the confinement of insulating Li2O2 within the pores and the presence of Co electrocatalysts. Therefore, the self‐standing porous architecture significantly enhances the cell's practical specific energy, achieving a high value of 798 Wh kg?1cell. This study provides an effective approach to increase the practical specific energy for Li–O2 batteries by constructing 3D‐printed framework cathodes.  相似文献   

8.
Efficient energy storage systems impact profoundly the renewable energy future. The performance of current electrical energy storage technologies falls well short of requirements for using electrical energy efficiently in transportation, commercial, and residential applications. This paper explores the possibility by using transition‐metal‐based complexes as active materials in a Li‐ion battery full cell that synergizes the concept of both lithium‐ion batteries and redox flow batteries. A cathode made from transition metal complex, [Fe(bpy)3](BF4)2, exhibits high discharge voltage approaching 4 V (vs Li/Li+). When coupled with a Li4Ti5O12 anode, the Li‐ion full battery exhibits a cell voltage exceeding 2.2 V and decent cycling efficiencies with Coulombic efficiency and energy/voltage efficiencies above 99% and 92%/93%, respectively. Such a Li‐ion battery full cell offers distinct features such as low cost and flexibility in molecular structure design. The result reveals a generic design route toward iron‐based complexes as cathode materials with good electrochemical performances.  相似文献   

9.
Highly Li‐ion conductive Li4(BH4)3I@SBA‐15 is synthesized by confining the LiI doped LiBH4 into mesoporous silica SBA‐15. Uniform nanoconfinement of P63 mc phase Li4(BH4)3I in SBA‐15 mesopores leads to a significantly enhanced conductivity of 2.5 × 10?4 S cm?1 with a Li‐ion transference number of 0.97 at 35 °C. The super Li‐ion mobility in the interface layer with a thickness of 1.2 nm between Li4(BH4)3I and SBA‐15 is believed to be responsible for the fast Li‐ion conduction in Li4(BH4)3I@SBA‐15. Additionally, Li4(BH4)3I@SBA‐15 also exhibits a wide apparent electrochemical stability window (0 to 5 V vs Li/Li+) and a superior Li dendrite suppression capability (critical current density 2.6 mA cm?2 at 55 °C) due to the formation of stable interphases. More importantly, Li4(BH4)3I@SBA‐15‐based Li batteries using either high‐capacity sulfur cathode or high‐voltage oxide cathode show excellent electrochemical performances, making Li4(BH4)3I@SBA‐15 a very attractive electrolyte for next‐generation all‐solid‐state Li batteries.  相似文献   

10.
Uncontrollable dendritic behavior and infinite volume expansion in alkali metal anode results in the severe safety hazards and short lifespan for high‐energy batteries. Constructing a stable host with superior Na/Li‐philic properties is a prerequisite for commercialization. Here, it is demonstrated that the small Gibbs free energy change in the reaction between metal oxide (Co3O4, SnO2, and CuO) and alkali metal is key for metal infusion. The as‐prepared hierarchical Co3O4 nanofiber–carbon sheet (CS) skeleton shows improved wettability toward molten Li/Na. The 3D carbon sheet serves as a primary framework, offering adequate lithium nucleation sites and sufficient electrolyte/electrode contact for fast charge transfer. The secondary framework of Co/Li2O nanofibers provides physical confinement of deposited Li and further redistributes the Li+ flux on each carbon fiber, which is verified by COMSOL Multiphysics simulations. Due to the uniform deposition behavior and near‐zero volume change, modified symmetrical Li/Li cells can operate under an ultrahigh current density of 20 mA cm?2 for more than 120 cycles. When paired with LiFePO4 cathodes, the Li/Co–CS cell shows low polarization and 88.4% capacity retention after 200 cycles under 2 C. Convincing improvement can also be observed in Na/Co–CS symmetrical cells applying NaClO4‐based electrolyte. These results illustrate a significant improvement in developing safe and stable alkali metal batteries.  相似文献   

11.
High‐energy‐density lithium metal batteries are considered the most promising candidates for the next‐generation energy storage systems. However, conventional electrolytes used in lithium‐ion batteries can hardly meet the demand of the lithium metal batteries due to their intrinsic instability for Li metal anodes and high‐voltage cathodes. Herein, an ester‐based electrolyte with tris(trimethylsilyl)phosphate additive that can form stable solid electrolyte interphases on the anode and cathode is reported. The additive decomposes before the ester solvent and enables the formation of P‐ and Si‐rich interphases on both electrodes that are ion conductive and robust. Thus, lithium metal batteries with a high‐specific‐energy of 373 Wh kg?1 can exhibit a long lifespan of over 80 cycles under practical conditions, including a low negative/positive capacity ratio of 2.3, high areal capacity of 4.5 mAh cm?2 for cathode, high‐voltage of 4.5 V, and lean electrolyte of 2.8 µL mAh?1. A 4.5 V pouch cell is further assembled to demonstrate the practical application of the tris(trimethylsilyl)phosphate additive with an areal capacity of 10.2 and 9.4 mAh cm?2 for the anode and cathode, respectively. This work is expected to provide an effective electrolyte optimizing strategy compatible with current lithium ion battery manufacturing systems and pave the way for the next‐generation Li metal batteries with high specific energy and energy density.  相似文献   

12.
Lithium–carbon dioxide (Li–CO2) batteries have received wide attention due to their high theoretical energy density and CO2 capture capability. However, this system still faces poor cycling performance and huge overpotential, which stems from the leakage/volatilization of liquid electrolyte and instability of the cathode. A gel polymer electrolyte (GPE)‐based Li–CO2 battery by using a novel pencil‐trace cathode and 0.0025 mol L?1 (M) binuclear cobalt phthalocyanine (Bi‐CoPc)‐containing GPE (Bi‐CoPc‐GPE) is developed here. The cathode, which is prepared by pencil drawing on carbon paper, is stable because of its typical limited‐layered graphitic structure without any binder. In addition, Bi‐CoPc‐GPE, which consists of polymer matrix filled with liquid electrolyte, exhibits excellent ion conductivity (0.86 mS cm?1), effective protection for Li anode, and superior leakproof property. Moreover, Bi‐CoPc acts as a redox mediator to promote the decomposition of discharge products at low charge potential. Interestingly, different from polymer‐shaped discharge products formed in liquid electrolyte–based Li–CO2 batteries, the morphology of products in Li–CO2 batteries using Bi‐CoPc‐GPE is film‐like. Hence, this polymer‐based Li–CO2 battery shows super‐high discharge capacity, low overpotential, and even steadily runs for 120 cycles. This study may pave a new way to develop high‐performance Li–CO2 batteries.  相似文献   

13.
The application of Li‐S batteries is hindered by low sulfur utilization and rapid capacity decay originating from slow electrochemical kinetics of polysulfide transformation to Li2S at the second discharge plateau around 2.1 V and harsh shuttling effects for high‐S‐loading cathodes. Herein, a cobalt‐doped SnS2 anchored on N‐doped carbon nanotube (NCNT@Co‐SnS2) substrate is rationally designed as both a polysulfide shield to mitigate the shuttling effects and an electrocatalyst to improve the interconversion kinetics from polysulfides to Li2S. As a result, high‐S‐loading cathodes are demonstrated to achieve good cycling stability with high sulfur utilization. It is shown that Co‐doping plays an important role in realizing high initial capacity and good capacity retention for Li‐S batteries. The S/NCNT@Co‐SnS2 cell (3 mg cm?2 sulfur loading) delivers a high initial specific capacity of 1337.1 mA h g?1 (excluding the Co‐SnS2 capacity contribution) and 1004.3 mA h g?1 after 100 cycles at a current density of 1.3 mA cm?2, while the counterpart cell (S/NCNT@SnS2) only shows an initial capacity of 1074.7 and 843 mA h g?1 at the 100th cycle. The synergy effect of polysulfide confinement and catalyzed polysulfide conversion provides an effective strategy in improving the electrochemical performance for high‐sulfur‐loading Li‐S batteries.  相似文献   

14.
In recent years, organic battery cathode materials have emerged as an attractive alternative to metal oxide–based cathodes. Organic redox polymers that can be reversibly oxidized are particularly promising. A drawback, however, often is their limited cycling stability and rate performance in a high voltage range of more than 3.4 V versus Li/Li+. Herein, a conjugated copolymer design with phenothiazine as a redox‐active group and a bithiophene co‐monomer is presented, enabling ultra‐high rate capability and cycling stability. After 30 000 cycles at a 100C rate, >97% of the initial capacity is retained. The composite electrodes feature defined discharge potentials at 3.6 V versus Li/Li+ due to the presence of separated phenothiazine redox centers. The semiconducting nature of the polymer allows for fast charge transport in the composite electrode at a high mass loading of 60 wt%. A comparison with three structurally related polymers demonstrates that changing the size, amount, or nature of the side groups leads to a reduced cell performance. This conjugated copolymer design can be used in the development of advanced redox polymers for batteries.  相似文献   

15.
Li‐rich layered cathode materials have been considered as a family of promising high‐energy density cathode materials for next generation lithium‐ion batteries (LIBs). However, although activation of the Li2MnO3 phase is known to play an essential role in providing superior capacity, the mechanism of activation of the Li2MnO3 phase in Li‐rich cathode materials is still not fully understood. In this work, an interesting Li‐rich cathode material Li1.87Mn0.94Ni0.19O3 is reported where the Li2MnO3 phase activation process can be effectively controlled due to the relatively low level of Ni doping. Such a unique feature offers the possibility of investigating the detailed activation mechanism by examining the intermediate states and phases of the Li2MnO3 during the controlled activation process. Combining powerful synchrotron in situ X‐ray diffraction analysis and observations using advanced scanning transmission electron microscopy equipped with a high angle annular dark field detector, it has been revealed that the subreaction of O2 generation may feature a much faster kinetics than the transition metal diffusion during the Li2MnO3 activation process, indicating that the latter plays a crucial role in determining the Li2MnO3 activation rate and leading to the unusual stepwise capacity increase over charging cycles.  相似文献   

16.
Lithium‐metal batteries are of particular interest for next‐generation electrical energy storage because of their high energy density on both volumetric and gravimetric bases. Effective strategies to stabilize the Li‐metal anode are the prerequisite for the progress of these exceptional storage technologies, such as Li–S and Li–O2 batteries. Various challenges, such as uneven Li electrodeposition, anode volume expansion, and dendrite‐induced short‐circuit have hindered the practical application of rechargeable Li‐metal batteries. Herein, a one‐step facile and cost‐effective strategy for stabilizing lithium‐metal batteries via 3D porous Cu current collector/Li‐metal composite anode is reported. The porous structure of the composite electrode provides a “cage” for the redeposition of “hostless” lithium and accommodates the anode volume expansion during cycling. Compared with planar Cu foil, its high specific surface area favors the electrochemical reaction kinetics and lowers the local current density along the anode. It leads to low interfacial resistance and stabilizes the Li electrodeposition. On this basis, galvanostatic measurements are performed on both symmetric cells and Li/Li4Ti5O12 cells and it is found that the electrodes exhibit exceptional abilities of promoting cell lifetime and stabilizing the cycling behavior. Although this work focuses on lithium metal, this novel tactic is easy to generalize to other metal electrodes.  相似文献   

17.
Although lithium–sulfur (Li–S) batteries are one of the most promising energy storage devices owing to their high energy densities, the sluggish reaction kinetics and severe shuttle effect of the sulfur cathodes hinder their practical applications. Here, single atom zinc implanted MXene is introduced into a sulfur cathode, which can not only catalyze the conversion reactions of polysulfides by decreasing the energy barriers from Li2S4 to Li2S2/Li2S but also achieve strong interaction with polysulfides due to the high electronegativity of atomic zinc on MXene. Moreover, it is found that the homogenously dispersed zinc atoms can also accelerate the nucleation of Li2S2/Li2S on MXene layers during the redox reactions. As a result, the sulfur cathode with single atom zinc implanted MXene exhibits a high reversible capacity of 1136 mAh g?1. After electrode optimization, a high areal capacity of 5.3 mAh cm?2, high rate capability of 640 mAh g?1 at 6 C, and good cycle stability (80% capacity retention after 200 cycles at 4 C) can be achieved.  相似文献   

18.
With the significant progress made in the development of cathodes in lithium‐sulfur (Li‐S) batteries, the stability of Li metal anodes becomes a more urgent challenge in these batteries. Here the systematic investigation of the stability of the anode/electrolyte interface in Li‐S batteries with concentrated electrolytes containing various lithium salts is reported. It is found that Li‐S batteries using LiTFSI‐based electrolytes are more stable than those using LiFSI‐based electrolytes. The decreased stability is because the N–S bond in the FSI? anion is fairly weak and the scission of this bond leads to the formation of lithium sulfate (LiSOx) in the presence of polysulfide species. In contrast, in the LiTFSI‐based electrolyte, the lithium metal anode tends to react with polysulfide to form lithium sulfide (LiSx), which is more reversible than LiSOx formed in the LiFSI‐based electrolyte. This fundamental difference in the bond strength of the salt anions in the presence of polysulfide species leads to a large difference in the stability of the anode‐electrolyte interface and performance of the Li‐S batteries with electrolytes composed of these salts. Therefore, anion selection is one of the key parameters in the search for new electrolytes for stable operation of Li‐S batteries.  相似文献   

19.
Lithium–sulfur (Li–S) batteries present one of the most promising energy storage systems owing to their high energy density and low cost. However, the commercialization of Li–S batteries is still hindered by several technical issues; the notorious polysulfide shuttling and sluggish sulfur conversion kinetics. In this work, unique hierarchical Fe3‐xC@C hollow microspheres as an advanced sulfur immobilizer and promoter for enabling high‐efficiency Li–S batteries is developed. The porous hollow architecture not only accommodates the volume variation upon the lithiation–delithiation processes, but also exposes vast active interfaces for facilitated sulfur redox reactions. Meanwhile, the mesoporous carbon coating establishes a highly conductive network for fast electron transportation. More importantly, the defective Fe3‐xC nanosized subunits impose strong LiPS adsorption and catalyzation, enabling fast and durable sulfur electrochemistry. Attributed to these structural superiorities, the obtained sulfur electrodes exhibit excellent electrochemical performance, i.e., high areal capacity of 5.6 mAh cm?2, rate capability up to 5 C, and stable cycling over 1000 cycles with a low capacity fading rate of 0.04% per cycle at 1 C, demonstrating great promise in the development of practical Li–S batteries.  相似文献   

20.
The main obstacles that hinder the development of efficient lithium sulfur (Li–S) batteries are the polysulfide shuttling effect in sulfur cathode and the uncontrollable growth of dendritic Li in the anode. An all‐purpose flexible electrode that can be used both in sulfur cathode and Li metal anode is reported, and its application in wearable and portable storage electronic devices is demonstrated. The flexible electrode consists of a bimetallic CoNi nanoparticle‐embedded porous conductive scaffold with multiple Co/Ni‐N active sites (CoNi@PNCFs). Both experimental and theoretical analysis show that, when used as the cathode, the CoNi and Co/Ni‐N active sites implanted on the porous CoNi@PNCFs significantly promote chemical immobilization toward soluble lithium polysulfides and their rapid conversion into insoluble Li2S, and therefore effectively mitigates the polysulfide shuttling effect. Additionally, a 3D matrix constructed with porous carbonous skeleton and multiple active centers successfully induces homogenous Li growth, realizing a dendrite‐free Li metal anode. A Li–S battery assembled with S/CoNi@PNCFs cathode and Li/CoNi@PNCFs anode exhibits a high reversible specific capacity of 785 mAh g?1 and long cycle performance at 5 C (capacity fading rate of 0.016% over 1500 cycles).  相似文献   

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