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1.
In an effort to develop high‐energy‐density cathodes for sodium‐ion batteries (SIBs), low‐cost, high capacity Na(Li1/3Mn2/3)O2 is discovered, which utilizes the labile O 2p‐electron for charge compensation during the intercalation process, inspired by Li2MnO3 redox reactions. Na(Li1/3Mn2/3)O2 is systematically designed by first‐principles calculations considering the Li/Na mixing enthalpy based on the site preference of Na in the Li sites of Li2MnO3. Using the anionic redox reaction (O2?/O?), this Mn‐oxide is predicted to show high redox potentials (≈4.2 V vs Na/Na+) with high charge capacity (190 mAh g?1). Predicted cathode performance is validated by experimental synthesis, characterization, and cyclic performance studies. Through a fundamental understanding of the redox reaction mechanism in Li2MnO3, Na(Li1/3Mn2/3)O2 is designed as an example of a new class of promising cathode materials, Na(Li1/3M2/3)O2 (M: transition metals featuring stabilized M4+), for further advances in SIBs.  相似文献   

2.
Molybdenum ditelluride nanosheets encapsulated in few‐layer graphene (MoTe2/FLG) are synthesized by a simple heating method using Te and Mo powder and subsequent ball milling with graphite. The as‐prepared MoTe2/FLG nanocomposites as anode materials for lithium‐ion batteries exhibit excellent electrochemical performance with a highly reversible capacity of 596.5 mAh g?1 at 100 mA g?1, a high rate capability (334.5 mAh g?1 at 2 A g?1), and superior cycling stability (capacity retention of 99.5% over 400 cycles at 0.5 A g?1). Ex situ X‐ray diffraction and transmission electron microscopy are used to explore the lithium storage mechanism of MoTe2. Moreover, the electrochemical performance of a MoTe2/FLG//0.35Li2MnO3·0.65LiMn0.5Ni0.5O2 full cell is investigated, which displays a reversible capacity of 499 mAh g?1 (based on the MoTe2/FLG mass) at 100 mA g?1 and a capacity retention of 78% over 50 cycles, suggesting the promising application of MoTe2/FLG for lithium‐ion storage. First‐principles calculations exhibit that the lowest diffusion barrier (0.18 eV) for lithium ions along pathway III in the MoTe2 layered structure is beneficial for improving the Li intercalation/deintercalation property.  相似文献   

3.
Conventional cathodes of Li‐ion batteries mainly operate through an insertion–extraction process involving transition metal redox. These cathodes will not be able to meet the increasing requirements until lithium‐rich layered oxides emerge with beyond‐capacity performance. Nevertheless, in‐depth understanding of the evolution of crystal and excess capacity delivered by Li‐rich layered oxides is insufficient. Herein, various in situ technologies such as X‐ray diffraction and Raman spectroscopy are employed for a typical material Li1.2Ni0.2Mn0.6O2, directly visualizing O?? O? (peroxo oxygen dimers) bonding mostly along the c‐axis and demonstrating the reversible O2?/O? redox process. Additionally, the formation of the peroxo O? O bond is calculated via density functional theory, and the corresponding O? O bond length of ≈1.3 Å matches well with the in situ Raman results. These findings enrich the oxygen chemistry in layered oxides and open opportunities to design high‐performance positive electrodes for lithium‐ion batteries.  相似文献   

4.
High and balanced electronic and ionic transportation networks with nanoscale distribution in solid‐state cathodes are crucial to realize high‐performance all‐solid‐state lithium batteries. Using Cu2SnS3 as a model active material, such a kind of solid‐state Cu2SnS3@graphene‐Li7P3S11 nanocomposite cathodes are synthesized, where 5–10 nm Cu2SnS3 nanoparticles homogenously anchor on the graphene nanosheets, while the Li7P3S11 electrolytes uniformly coat on the surface of Cu2SnS3@graphene composite forming nanoscaled electron/ion transportation networks. The large amount of nanoscaled triple‐phase boundary in cathode ensures high power density due to high ionic/electronic conductions and long cycle life due to uniform and reduced volume change of nano‐Cu2SnS3. The Cu2SnS3@graphene‐Li7P3S11 cathode layer with 2.0 mg cm?2 loading in all‐solid‐state lithium batteries demonstrates a high reversible discharge specific capacity of 813.2 mAh g?1 at 100 mA g?1 and retains 732.0 mAh g?1 after 60 cycles, corresponding to a high energy density of 410.4 Wh kg?1 based on the total mass of Cu2SnS3@graphene‐Li7P3S11 composite based cathode. Moreover, it exhibits excellent rate capability and high‐rate cycling stability, showing reversible capacity of 363.5 mAh g?1 at 500 mA g?1 after 200 cycles. The study provides a new insight into constructing both electronic and ionic conduction networks for all‐solid‐state lithium batteries.  相似文献   

5.
Novel and low‐cost batteries are of considerable interest for application in large‐scale energy storage systems, for which the cost per cycle becomes critical. Here, this study proposes K0.5MnO2 as a potential cathode material for K‐ion batteries as an alternative to Li technology. K0.5MnO2 has a P3‐type layered structure and delivers a reversible specific capacity of ≈100 mAh g?1 with good capacity retention. In situ X‐ray diffraction analysis reveals that the material undergoes a reversible phase transition upon K extraction and insertion. In addition, first‐principles calculations indicate that this phase transition is driven by the relative phase stability of different oxygen stackings with respect to the K content.  相似文献   

6.
Li‐rich oxide cathodes are of prime importance for the development of high‐energy lithium‐ion batteries (LIBs). Li‐rich layered oxides, however, always undergo irreversible structural evolution, leading to inevitable capacity and voltage decay during cycling. Meanwhile, Li‐rich cation‐disordered rock‐salt oxides usually exhibit sluggish kinetics and inferior cycling stability, despite their firm structure and stable voltage output. Herein, a new Li‐rich rock‐salt oxide Li2Ni1/3Ru2/3O3 with Fd‐3m space group, where partial cation‐ordering arrangement exists in cationic sites, is reported. Results demonstrate that a cathode fabricated from Li2Ni1/3Ru2/3O3 delivers a large capacity, outstanding rate capability as well as good cycling performance with negligible voltage decay, in contrast to the common cations disordered oxides with space group Fm‐3m. First principle calculations also indicate that rock‐salt oxide with space group Fd‐3m possesses oxygen activity potential at the state of delithiation, and good kinetics with more 0‐TM (TM = transition metals) percolation networks. In situ Raman results confirm the reversible anionic redox chemistry, confirming O2?/O? evolution during cycles in Li‐rich rock‐salt cathode for the first time. These findings open up the opportunity to design high‐performance oxide cathodes and promote the development of high‐energy LIBs.  相似文献   

7.
Lithium–oxygen (Li–O2) batteries are attracting more attention owing to their superior theoretical energy density compared to conventional Li‐ion battery systems. With regards to the catalytically electrochemical reaction on a cathode, the electrocatalyst plays a key role in determining the performance of Li–O2 batteries. Herein, a new 3D hollow α‐MnO2 framework (3D α‐MnO2) with porous wall assembled by hierarchical α‐MnO2 nanowires is prepared by a template‐induced hydrothermal reaction and subsequent annealing treatment. Such a distinctive structure provides some essential properties for Li–O2 batteries including the intrinsic high catalytic activity of α‐MnO2, more catalytic active sites of hierarchical α‐MnO2 nanowires on 3D framework, continuous hollow network and rich porosity for the storage of discharge product aggregations, and oxygen diffusion. As a consequence, 3D α‐MnO2 achieves a high specific capacity of 8583 mA h g?1 at a current density of 100 mA g?1, a superior rate capacity of 6311 mA h g?1 at 300 mA g?1, and a very good cycling stability of 170 cycles at a current density of 200 mA g?1 with a fixed capacity of 1000 mA h g?1. Importantly, the presented design strategy of 3D hollow framework in this work could be extended to other catalytic cathode design for Li–O2 batteries.  相似文献   

8.
The major challenges faced by candidate electrode materials in lithium‐ion batteries (LIBs) include their low electronic and ionic conductivities. 2D van der Waals materials with good electronic conductivity and weak interlayer interaction have been intensively studied in the electrochemical processes involving ion migrations. In particular, molybdenum ditelluride (MoTe2) has emerged as a new material for energy storage applications. Though 2H‐MoTe2 with hexagonal semiconducting phase is expected to facilitate more efficient ion insertion/deinsertion than the monoclinic semi‐metallic phase, its application as an anode in LIB has been elusive. Here, 2H‐MoTe2, prepared by a solid‐state synthesis route, has been employed as an efficient anode with remarkable Li+ storage capacity. The as‐prepared 2H‐MoTe2 electrodes exhibit an initial specific capacity of 432 mAh g?1 and retain a high reversible specific capacity of 291 mAh g?1 after 260 cycles at 1.0 A g?1. Further, a full‐cell prototype is demonstrated by using 2H‐MoTe2 anode with lithium cobalt oxide cathode, showing a high energy density of 454 Wh kg?1 (based on the MoTe2 mass) and capacity retention of 80% over 100 cycles. Synchrotron‐based in situ X‐ray absorption near‐edge structures have revealed the unique lithium reaction pathway and storage mechanism, which is supported by density functional theory based calculations.  相似文献   

9.
Inspired by its high‐active and open layered framework for fast Li+ extraction/insertion reactions, layered Ni‐rich oxide is proposed as an outstanding Na‐intercalated cathode for high‐performance sodium‐ion batteries. An O3‐type Na0.75Ni0.82Co0.12Mn0.06O2 is achieved through a facile electrochemical ion‐exchange strategy in which Li+ ions are first extracted from the LiNi0.82Co0.12Mn0.06O2 cathode and Na+ ions are then inserted into a layered oxide framework. Furthermore, the reaction mechanism of layered Ni‐rich oxide during Na+ extraction/insertion is investigated in detail by combining ex situ X‐ray diffraction, X‐ray photoelectron spectroscopy, and electron energy loss spectroscopy. As an excellent cathode for Na‐ion batteries, O3‐type Na0.75Ni0.82Co0.12Mn0.06O2 delivers a high reversible capacity of 171 mAh g?1 and a remarkably stable discharge voltage of 2.8 V during long‐term cycling. In addition, the fast Na+ transport in the cathode enables high rate capability with 89 mAh g?1 at 9 C. The as‐prepared Ni‐rich oxide cathode is expected to significantly break through the limited performance of current sodium‐ion batteries.  相似文献   

10.
Lithium ion capacitors are new energy storage devices combining the complementary features of both electric double‐layer capacitors and lithium ion batteries. A key limitation to this technology is the kinetic imbalance between the Faradaic insertion electrode and capacitive electrode. Here, we demonstrate that the Li3VO4 with low Li‐ion insertion voltage and fast kinetics can be favorably used for lithium ion capacitors. N‐doped carbon‐encapsulated Li3VO4 nanowires are synthesized through a morphology‐inheritance route, displaying a low insertion voltage between 0.2 and 1.0 V, a high reversible capacity of ≈400 mAh g?1 at 0.1 A g?1, excellent rate capability, and long‐term cycling stability. Benefiting from the small nanoparticles, low energy diffusion barrier and highly localized charge‐transfer, the Li3VO4/N‐doped carbon nanowires exhibit a high‐rate pseudocapacitive behavior. A lithium ion capacitor device based on these Li3VO4/N‐doped carbon nanowires delivers a high energy density of 136.4 Wh kg?1 at a power density of 532 W kg?1, revealing the potential for application in high‐performance and long life energy storage devices.  相似文献   

11.
Ti–Nb–O binary oxide materials represent a family of promising intercalating anode materials for lithium‐ion batteries. In additional to their excellent capacities (388–402 mAh g–1), these materials show excellent safety characteristics, such as an operating potential above the lithium plating voltage and minimal volume change. Herein, this study reports a new member in the Ti–Nb–O family, Ti2Nb14O39, as an advanced anode material. Ti2Nb14O39 porous spheres (Ti2Nb14O39‐S) exhibit a defective shear ReO3 crystal structure with a large unit cell volume and a large amount of cation vacancies (0.85% vs all cation sites). These morphological and structural characteristics allow for short electron/Li+‐ion transport length and fast Li+‐ion diffusivity. Consequently, the Ti2Nb14O39‐S material delivers significant pseudocapacitive behavior and excellent electrochemical performances, including high reversible capacity (326 mAh g?1 at 0.1 C), high first‐cycle Coulombic efficiency (87.5%), safe working potential (1.67 V vs Li/Li+), outstanding rate capability (223 mAh g–1 at 40 C) and durable cycling stability (only 0.032% capacity loss per cycle over 200 cycles at 10 C). These impressive results clearly demonstrate that Ti2Nb14O39‐S can be a promising anode material for fast‐charging, high capacity, safe and stable lithium‐ion batteries.  相似文献   

12.
Potassium‐ion batteries (PIBs) are one of the emerging energy‐storage technologies due to the low cost of potassium and theoretically high energy density. However, the development of PIBs is hindered by the poor K+ transport kinetics and the structural instability of the cathode materials during K+ intercalation/deintercalation. In this work, birnessite nanosheet arrays with high K content (K0.77MnO2?0.23H2O) are prepared by “hydrothermal potassiation” as a potential cathode for PIBs, demonstrating ultrahigh reversible specific capacity of about 134 mAh g?1 at a current density of 100 mA g?1, as well as great rate capability (77 mAh g?1 at 1000 mA g?1) and superior cycling stability (80.5% capacity retention after 1000 cycles at 1000 mA g?1). With the introduction of adequate K+ ions in the interlayer, the K‐birnessite exhibits highly stabilized layered structure with highly reversible structure variation upon K+ intercalation/deintercalation. The practical feasibility of the K‐birnessite cathode in PIBs is further demonstrated by constructing full cells with a hard–soft composite carbon anode. This study highlights effective K+‐intercalation for birnessite to achieve superior K‐storage performance for PIBs, making it a general strategy for developing high‐performance cathodes in rechargeable batteries beyond lithium‐ion batteries.  相似文献   

13.
The Li‐CO2 battery is an emerging green energy technology coupling CO2 capture and conversion. The main drawback of present Li‐CO2 batteries is serious polarization and poor cycling caused by random deposition of lithium ions and big insulated Li2CO3 formation on the cathode during discharge. Herein, covalent organic frameworks (COF) are identified as the porous catalyst in the cathode of Li‐CO2 batteries for the first time. Graphene@COF is fabricated, graphene with thin and uniform imine COF loading, to enrich and confine CO2 in the nanospaces of micropores. The discharge voltage is raised by higher local CO2 concentration, which is predicted by the Nernst equation and realized by CO2 nanoenrichment. Moreover, uniform lithium ion deposition directed by the graphene@COF nanoconfined CO2 can produce smaller Li2CO3 particles, leading to easier Li2CO3 decomposition and thus lower charge voltage. The graphene@COF cathode with 47.5% carbon content achieves a discharge capacity of 27833 mAh g?1 at 75 mA g?1, while retaining a low charge potential of 3.5 V at 0.5 A g?1 for 56 cycles.  相似文献   

14.
Covalent organic frameworks (COFs) are an emerging class of porous crystalline materials constructed from designer molecular building blocks that are linked and extended periodically via covalent bonds. Their high stability, open channels, and ease of functionalization suggest that they can function as a useful cathode material in reversible lithium batteries. Here, a COF constructed from hydrazone/hydrazide‐containing molecular units, which shows good CO2 sequestration properties, is reported. The COF is hybridized to Ru‐nanoparticle‐coated carbon nanotubes, and the composite is found to function as highly efficient cathode in a Li–CO2 battery. The robust 1D channels in the COF serve as CO2 and lithium‐ion‐diffusion channels and improve the kinetics of electrochemical reactions. The COF‐based Li–CO2 battery exhibits an ultrahigh capacity of 27 348 mAh g?1 at a current density of 200 mA g?1, and a low cut‐off overpotential of 1.24 V within a limiting capacity of 1000 mAh g?1. The rate performance of the battery is improved considerably with the use of the COF at the cathode, where the battery shows a slow decay of discharge voltage from a current density of 0.1 to 4 A g?1. The COF‐based battery runs for 200 cycles when discharged/charged at a high current density of 1 A g?1.  相似文献   

15.
Rechargeable Li–CO2 batteries have attracted worldwide attention due to the capability of CO2 capture and superhigh energy density. However, they still suffer from poor cycling performance and huge overpotential. Thus, it is essential to explore highly efficient catalysts to improve the electrochemical performance of Li–CO2 batteries. Here, phytic acid (PA)‐cross‐linked ruthenium complexes and melamine are used as precursors to design and synthesize RuP2 nanoparticles highly dispersed on N, P dual‐doped carbon films (RuP2‐NPCFs), and the obtained RuP2‐NPCF is further applied as the catalytic cathode for Li–CO2 batteries. RuP2 nanoparticles that are uniformly deposited on the surface of NPCF show enhanced catalytic activity to decompose Li2CO3 at low charge overpotential. In addition, the NPCF its with porous structure in RuP2‐NPCF provides superior electrical conductivity, high electrochemical stability, and enough ion/electron and space for the reversible reaction in Li–CO2 batteries. Hence, the RuP2‐NPCF cathode delivers a superior reversible discharge capacity of 11951 mAh g?1, and achieves excellent cyclability for more than 200 cycles with low overpotentials (<1.3 V) at the fixed capacity of 1000 mAh g?1. This work paves a new way to design more effective catalysts for Li–CO2 batteries.  相似文献   

16.
1T phase MoS2 possesses higher conductivity than the 2H phase, which is a key parameter of electrochemical performance for lithium ion batteries (LIBs). Herein, a 1T‐MoS2/C hybrid is successfully synthesized through facile hydrothermal method with a proper glucose additive. The synthesized hybrid material is composed of smaller and fewer‐layer 1T‐MoS2 nanosheets covered by thin carbon layers with an enlarged interlayer spacing of 0.94 nm. When it is used as an anode material for LIBs, the enlarged interlayer spacing facilitates rapid intercalating and deintercalating of lithium ions and accommodates volume change during cycling. The high intrinsic conductivity of 1T‐MoS2 also contributes to a faster transfer of lithium ions and electrons. Moreover, much smaller and fewer‐layer nanosheets can shorten the diffusion path of lithium ions and accelerate reaction kinetics, leading to an improved electrochemical performance. It delivers a high initial capacity of 920.6 mAh g?1 at 1 A g?1 and the capacity can maintain 870 mAh g?1 even after 300 cycles, showing a superior cycling stability. The electrode presents a high rate performance as well with a reversible capacity of 600 mAh g?1 at 10 A g?1. These results show that the 1T‐MoS2/C hybrid shows potential for use in high‐performance lithium‐ion batteries.  相似文献   

17.
Manganese oxides (MnOx) are promising anode materials for lithium ion batteries, but they generally exhibit mediocre performances due to intrinsic low ionic conductivity, high polarization, and poor stability. Herein, yolk–shell nanorods comprising of nitrogen‐doped carbon (N–C) coating on manganese monoxide (MnO) coupled with zinc manganate (ZnMn2O4) nanoparticles are manufactured via one‐step carbonization of α‐MnO2/ZIF‐8 precursors. When evaluated as anodes for lithium ion batteries, MnO@ZnMn2O4/N–C exhibits an reversible capacity of 803 mAh g?1 at 50 mA g?1 after 100 cycles, excellent cyclability with a capacity of 595 mAh g?1 at 1000 mAg?1 after 200 cycles, as well as better rate capability compared with those non‐N–C shelled manganese oxides (MnOx). The outstanding electrochemical performance is attributed to the unique yolk–shell nanorod structure, the coating effect of N–C and nanoscale size.  相似文献   

18.
All‐solid‐state Li–S batteries are promising candidates for next‐generation energy‐storage systems considering their high energy density and high safety. However, their development is hindered by the sluggish electrochemical kinetics and low S utilization due to high interfacial resistance and the electronic insulating nature of S. Herein, Se is introduced into S cathodes by forming SeSx solid solutions to modify the electronic and ionic conductivities and ultimately enhance cathode utilization in all‐solid‐state lithium batteries (ASSLBs). Theoretical calculations confirm the redistribution of electron densities after introducing Se. The interfacial ionic conductivities of all achieved SeSx–Li3PS4 (x = 3, 2, 1, and 0.33) composites are 10?6 S cm?1. Stable and highly reversible SeSx cathodes for sulfide‐based ASSLBs can be developed. Surprisingly, the SeS2/Li10GeP2S12–Li3PS4/Li solid‐state cells exhibit excellent performance and deliver a high capacity over 1100 mAh g?1 (98.5% of its theoretical capacity) at 50 mA g?1 and remained highly stable for 100 cycles. Moreover, high loading cells can achieve high areal capacities up to 12.6 mAh cm?2. This research deepens the understanding of Se–S solid solution chemistry in ASSLB systems and offers a new strategy to achieve high‐performance S‐based cathodes for application in ASSLBs.  相似文献   

19.
Covalent organic frameworks (COFs) with reversible redox behaviors are potential electrode materials for lithium‐ion batteries (LIBs). However, the sluggish lithium diffusion kinetics, poor electronic conductivity, low reversible capacities, and poor rate performance for most reported COF materials limit their further application. Herein, a new 2D COF (TFPB‐COF) with six unsaturated benzene rings per repeating unit and ordered mesoporous pores (≈2.1 nm) is designed. A chemical stripping strategy is developed to obtain exfoliated few‐layered COF nanosheets (E‐TFPB‐COF), whose restacking is prevented by the in situ formed MnO2 nanoparticles. Compared with the bulk TFPB‐COF, the exfoliated TFPB‐COF exhibits new active Li‐storage sites associated with conjugated aromatic π electrons by facilitating faster ion/electron kinetics. The E‐TFPB‐COF/MnO2 and E‐TFPB‐COF electrodes exhibit large reversible capacities of 1359 and 968 mAh g?1 after 300 cycles with good high‐rate capability.  相似文献   

20.
Fast lithium ion transport with a high current density is critical for thick sulfur cathodes, stemming mainly from the difficulties in creating effective lithium ion pathways in high sulfur content electrodes. To develop a high‐rate cathode for lithium–sulfur (Li–S) batteries, extenuation of the lithium ion diffusion barrier in thick electrodes is potentially straightforward. Here, a phyllosilicate material with a large interlamellar distance is demonstrated in high‐rate cathodes as high sulfur loading. The interlayer space (≈1.396 nm) incorporated into a low lithium ion diffusion barrier (0.155 eV) significantly facilitates lithium ion diffusion within the entire sulfur cathode, and gives rise to remarkable nearly sulfur loading‐independent cell performances. When combined with 80% sulfur contents, the electrodes achieve a high capacity of 865 mAh g?1 at 1 mA cm?2 and a retention of 345 mAh g?1 at a high discharging/charging rate of 15 mA cm?2, with a sulfur loading up to 4 mg. This strategy represents a major advance in high‐rate Li–S batteries via the construction of fast ions transfer paths toward real‐life applications, and contributes to the research community for the fundamental mechanism study of loading‐independent electrode systems.  相似文献   

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