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1.
Silicon (Si) and lithium metal are the most favorable anodes for high‐energy‐density lithium‐based batteries. However, large volume expansion and low electrical conductivity restrict commercialization of Si anodes, while dendrite formation prohibits the applications of lithium‐metal anodes. Here, uniform nanoporous Si@carbon (NPSi@C) from commercial alloy and CO2 is fabricated and tested as a stable anode for lithium‐ion batteries (LIBs). The porosity of Si as well as graphitization degree and thickness of the carbon layer can be controlled by adjusting reaction conditions. The rationally designed porosity and carbon layer of NPSi@C can improve electronic conductivity and buffer volume change of Si without destroying the carbon layer or disrupting the solid electrolyte interface layer. The optimized NPSi@C anode shows a stable cyclability with 0.00685% capacity decay per cycle at 5 A g?1 over 2000 cycles for LIBs. The energy storage mechanism is explored by quantitative kinetics analysis and proven to be a capacitance‐battery dual model. Moreover, a novel 2D/3D structure is designed by combining MXene and NPSi@C. As lithiophilic nucleation seeds, NPSi@C can induce uniform Li deposition with buffered volume expansion, which is proven by exploring Li‐metal deposition morphology on Cu foil and MXene@NPSi@C. The practical potential application of NPSi@C and MXene@NPSi@C is evaluated by full cell tests with a Li(Ni0.8Co0.1Mn0.1)O2 cathode.  相似文献   

2.
Lithium metal anodes are widely regarded as the ideal candidate for the next generation of high-energy-density lithium batteries. Here, a 3D host made of lithiophilic Mo2C clusters-embedded carbon nanofibers (Mo2C@CNF) is developed. The uniformly dispersed clusters and large specific surface areas of Mo2C@CNF provide numerous nucleation sites for lithium deposition. Mo2C clusters exhibit ultralow nucleation overpotential compared to MoO2, which is also supported by density functional theory calculations. Furthermore, the transition metal element serves as a catalyst for the formation of a stable and robust solid electrolyte interphase layer containing LiF on Mo2C@CNF, effectively mitigating the occurrence of dead lithium and enhancing the Coulombic efficiency during prolonged operation. As a result, the Mo2C@CNF composite delivers superior electrochemical performance (>1600 h) at 1 mA cm−2 and lower nucleation overpotential (13 mV) for lithium plating. The Li/Mo2C@CNF anode coupled with the commercial LiFePO4 cathode exhibits excellent cycling stability (300 cycles at 1 C) and high rate capability at low N/P ratios.  相似文献   

3.
The applications of lithium metal anode are limited by uncontrollable lithium dendrite growth and infinite volume changes during cycling. These fundamental issues are exacerbated at high cycling current densities and capacities. Herein, a mechanically stable and resilient lithium metal host is fabricated by covalently cross-linking a highly-conductive and lithiophilic MXene/silver nanowire scaffold through a silylation reaction between MXene nanosheets and polysiloxane. Compared with the control sample (an MXene scaffold assembled by weak van der Waals forces), the covalently cross-linked MXene scaffold displays excellent mechanical strength and resilience, which is conducive to buffer the large internal stress fluctuations generated during rapid and deep lithium plating-stripping and guaranteed that the integrated framework structure is maintained during long-term charging-discharging cycles. When used in a symmetric cell, the lithium composite anode based on the covalently cross-linked MXene host affords an unprecedented cyclic lithium plating-stripping stability of a record-high 3000 h lifespan at an ultrahigh current density (20 mA cm−2) and areal capacity (10 mAh cm−2). When this composite anode is coupled with a LiNi0.5Co0.2Mn0.3O2 cathode, the full cell delivers an ultrahigh rate of 10 C for up to 1000 cycles, with an average capacity decay of 0.043% per cycle and a stable Coulombic efficiency of 98.7%.  相似文献   

4.
A solid-state battery with a lithium-metal anode and a garnet-type solid electrolyte has been widely regarded as one of the most promising solutions to boost the safety and energy density of current lithium-ion batteries. However, lithiophobic property of garnet-type solid electrolytes hinders the establishment of a good physical contact with lithium metal, bringing about a large lithium/garnet interfacial resistance that has remained as the greatest issue facing their practical application in solid-state batteries. Herein, a melt-quenching approach is developed by which varieties of interfacial modification layers based on metal alloys can be coated uniformly on the surface of the garnet. It is demonstrated that with an ultrathin, lithiophilic AgSn0.6Bi0.4Ox coating the interfacial resistance can be eliminated, and a dendrite-free lithium plating and stripping on the lithium/garnet interface can be achieved at a high current density of 20 mA cm−2. The results reveal that the uniform coating on the garnet surface and the facile lithium diffusion through the coating layer are two major reasons for the excellent electrochemical performances. The all-solid-state full cell consisting of the surface modified garnet-type solid electrolyte with a LiNi0.8Mn0.1Co0.1O2 cathode and a lithium–metal anode maintains 86% of its initial capacity after 1000 stable cycles at 1 C.  相似文献   

5.
High-energy-density Li–S batteries are considered one of the next-generation energy storage systems, but the uncontrolled Li-dendrite growth in Li metal anodes and the shuttling of polysulfides in S cathode severely impede the commercial development of Li–S batteries. Herein, a conductive composite architecture that is made up of bio-derived N-doped porous carbon fiber bundles (N-PCFs) with co-imbedded cobalt and niobium carbide nanoparticles is employed as a multifunctional integrated host for simultaneously addressing the challenges in both Li anodes and S cathodes. The implantation of Co and NbC nanoparticles bestows the N-PCFs matrix with synergistically enhanced degree of graphitization, electrical conductivity, hierarchical porosity, and surface polarization. Theoretical calculations and experimental results show that NbC with specific lithiophilic and sulfiphilic features can synchronously regulate the Li and S electrochemistry by realizing homogeneous lithium deposition with suppressed Li-dendrite growth and exerting catalytic effects for promoting the polysulfide conversion together with fast Li2S nucleation. Hence, the assembled Li–S full batteries exhibit a superb rate capability (704 mAh g−1 at 5 C) and cycling life (≈82.3% capacity retention after 500 cycles) at a sulfur loading over 3.0 mg cm−2, as well as high reversible areal capacity (>6.0 mAh cm−2) even at a higher sulfur loading of 6.7 mg cm−2.  相似文献   

6.
Considerable endeavors are developed to suppress lithium (Li) dendrites and improve the cycling stability of Li metal batteries in order to promote their commercial application. Herein, continuous zinc (Zn) nanoparticles-assembled film with homogenous nanopores is proposed as a modified layer for separator via a scalable method. The in situ formed LiZn alloy film during initial Li plating can serve as a Li+ ion rectification and lithiophilic layer to regulate the nucleation and reverse deposition of Li. When applied in Li|LiFePO4 full cells with traditional carbonate-based electrolyte, the modified separator enables outstanding cycling stability of up to 350 cycles without capacity loss at a large rate of 5 C (3.4 mA cm−2) and a remarkable reversible capacity of 144 mAh g−1 after 120 cycles at a commercial mass loading as high as 19.72 mg cm−2. The excellent electrochemical performances are ascribed to the dendrite-free reverse Li deposition induced by modified layer by means of its lithiophilic property for regulating homogeneous Li nucleation on the separator as well as its well-distributed nanopores for homogenizing Li+ ion flux and enhancing electrolyte wetting.  相似文献   

7.
A vulnerable solid–electrolyte interphase (SEI) layer cannot retard Li dendrite growth, electrolyte consumption, and anode volumetric expansion, which seriously hinders the development of high-safety Li-metal batteries (LMBs). Herein, a dynamical SEI reinforced by an open-architecture metal–organic framework (OA-MOF) film characterized by elastic expansion and contraction of the volume of stereoscopic lithiophilic sites, is designed. The self-adjustment distribution of lithiophilic sites on vertically grown Cu2(BDC)2 nanosheets enables the homogenization of Li-ion flux, smart control of Li mass transport, and compaction of Li deposition. The trapped N, N-dimethylformamide molecules in the open framework structure are favorable for the better wetting and dissolution effect of Li-ions accessing to Cu2(BDC)2. Combining these advantages, the featured OA-MOF/Cu@Li anode enables a high coulombic efficiency and low voltage hysteresis in Li||Cu cells even at an ultrahigh current density of 15 mA cm−2.  相似文献   

8.
Lithium metal is an exciting anode candidate with extra high theoretical specific capacity for new high‐energy rechargeable batteries. However, uncontrolled Li deposition and an unsteady solid electrolyte interface seriously obstruct the commercial application of Li anodes in Li metal batteries. Herein, 3D carbon cloth (CC) supporting N‐doped carbon (CN) nanosheet arrays embedded with tiny Co nanoparticles (CC@CN‐Co) are employed as a lithiophilic framework to regulate homogenous Li nucleation/growth behavior in a working Li metal anode. The emergence of Li dendrites is supposed to be inhibited by the conductive 3D scaffold that reduces local current density. The uniform nucleation of Li can be guided by N‐containing functional groups as they have a strong interaction with Li atoms, and the tiny Co nanoparticles can provide active sites to guide Li deposition. As a result, the current CC@CN‐Co host exhibits Li dendrite–free features and stable cycling performance with a low overpotential (20 mV) throughout 800 h cycles. When paired with the typical LiFePO4 (LFP) cathode, the assembled CC@CN‐Co@Li//LFP@C full cell exhibits outstanding rate capability and improved cycling performance.  相似文献   

9.
Lithium (Li) metal, as an appealing candidate for the next-generation of high-energy-density batteries, is plagued by its safety issue mainly caused by uncontrolled dendrite growth and infinite volume expansion. Developing new materials that can improve the performance of Li-metal anode is one of the urgent tasks. Herein, a new MXene derivative containing pure rutile TiO2 and N-doped carbon prepared by heat-treating MXene under a mixing gas, exhibiting high chemical activity in molten Li, is reported. The lithiation MXene derivative with a hybrid of LiTiO2-Li3N-C and Li offers outstanding electrochemical properties. The symmetrical cell assembling lithiation MXene derivative hybrid anode exhibits an ultra-long cycle lifespan of 2000 h with an overpotential of ≈30 mV at 1 mA cm−2, which overwhelms Li-based anodes reported so far. Additionally, long-term operations of 34, 350, and 500 h at 10 mA cm−2 can be achieved in symmetrical cells at temperatures of −10, 25, and 50 °C, respectively. Both experimental tests and density functional theory calculations confirm that the LiTiO2-Li3N-C skeleton serves as a promising host for Li infusion by alleviating volume variation. Simultaneously, the superlithiophilic interphase of Li3N guides Li deposition along the LiTiO2-Li3N-C skeleton to avoid dendrite growth.  相似文献   

10.
Realizing long cycling stability under a high sulfur loading is an essential requirement for the practical use of lithium–sulfur (Li–S) batteries. Here, a lamellar aerogel composed of Ti3C2Tx MXene/carbon nanotube (CNT) sandwiches is prepared by unidirectional freeze-drying to boost the cycling stability of high sulfur loading batteries. The produced materials are denoted parallel-aligned MXene/CNT (PA-MXene/CNT) due to the unique parallel-aligned structure. The lamellae of MXene/CNT/MXene sandwich form multiple physical barriers, coupled with chemical trapping and catalytic activity of MXenes, effectively suppressing lithium polysulfide (LiPS) shuttling under high sulfur loading, and more importantly, substantially improving the LiPS confinement ability of 3D hosts free of micro- and mesopores. The assembled Li–S battery delivers a high capacity of 712 mAh g−1 with a sulfur loading of 7 mg cm−2, and a superior cycling stability with 0.025% capacity decay per cycle over 800 cycles at 0.5 C. Even with sulfur loading of 10 mg cm−2, a high areal capacity of above 6 mAh cm−2 is obtained after 300 cycles. This work presents a typical example for the rational design of a high sulfur loading host, which is critical for the practical use of Li–S batteries  相似文献   

11.
Sodium (Na) metal is a promising alternative to lithium metal as an anode material for the next‐generation energy storage systems due to its high theoretical capacity, low cost, and natural abundance. However, dendritic/mossy Na growth caused by uncontrollable plating/stripping results in serious safe concerns and rapid electrode degradation. This study presents Sn2+ pillared Ti3C2 MXene serving as a stable matrix for high‐performance dendrite‐free Na metal anode. The intercalated Sn2+ between Ti3C2 layers not only induces Na to nucleate and grow within Ti3C2 interlayers, but also endows the Ti3C2 with larger interlayer space to accommodate the deposited Na by taking advantage of the “pillar effect,” contributing to uniform Na deposition. As a result, the pillar‐structured MXene‐based Na metal electrode could enable high current density (up to 10 mA cm?2) along with high areal capacity (up to 5 mAh cm?2) over long‐term cycling (up to 500 cycles). The full cell using MXene‐based Na metal anode exhibits superior electrochemical performance than that using host‐less commercial Na. It is believed that the well‐controlled MXene‐based Na anode not only extends the application scope of MXene, but also provides guidance in designing high‐performance Na metal batteries.  相似文献   

12.
MXenes are an emerging class of 2D transition metal carbides and nitrides. They have been widely used in flexible electronics owing to their excellent conductivity, mechanical flexibility, and water dispersibility. In this study, the electrode and active layer applications of MXene materials in electronic skins are realized. By utilizing vacuum filtration technology, few-layer MXene electrodes are integrated onto the top and bottom surfaces of the 3D polyacrylonitrile (PAN) network to form a stable electronic skin. The fabricated flexible device with Ti3C2Tx MXene electrodes outperforms those with other electrodes and exhibits excellent device performance, with a high sensitivity of 104.0 kPa−1, fast response/recovery time of 30/20 ms, and a low detection limit of 1.5 Pa. Furthermore, the electrode and the constructed MXene/PAN-based flexible pressure sensor exhibit robust mechanical stability and can survive 240 bending cycles. Such a robust, flexible device can be enlarged or folded like a jigsaw puzzle or origami and transformed from 2D to 3D structures; moreover, it can detect tiny movements of human muscles, such as movements corresponding to sound production and intense movements during bending of fingers.  相似文献   

13.
Since discovered in 2011, transition metal carbides or nitrides (MXenes) have attracted enormous attention due to their unique properties. Morphology regulation strategies assembling 2D MXene sheets into 3D architecture have endowed the as-formed porous MXene with a better performance in various fields. However, the direct patterning strategy for the porous MXene into integration with multifunctional and multichannel electronic devices still needs to be investigated. The metal-assisted electro-gelation method the authors propose can directly generate porous-structured MXene hydrogel with a tunable feature. By electrolyzing the sacrificial metal, the released metal cations initiate the electro-gelation process during which electrostatic interactions occur between cations and the MXene sheets. A high spatial resolution down to micro-meter level is achieved utilizing the method, enabling high-performance hydrogels with more complex architectures. Electronics prepared through this metal-assisted electro-gelation process have shown promising applications of the porous MXene in energy and biochemical sensing fields. Energy storage devices with a capacitance at 33.3 mF cm−2 and biochemical sensors show prominent current responses towards metabolites (sensitivity of H2O2: 165.6  µ A mm −1 cm−2; sensitivity of DA: 212 nA  µ m −1 cm−2), suggesting that the metal-assisted electro-gelation method will become a prospective technique for advanced fabrication of MXene-based devices.  相似文献   

14.
MXenes, a young family of 2D transition metal carbides/nitrides, show great potential in electrochemical energy storage applications. Herein, a high performance ultrathin flexible solid‐state supercapacitor is demonstrated based on a Mo1.33C MXene with vacancy ordering in an aligned layer structure MXene/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) composite film posttreated with concentrated H2SO4. The flexible solid‐state supercapacitor delivers a maximum capacitance of 568 F cm?3, an ultrahigh energy density of 33.2 mWh cm?3 and a power density of 19 470 mW cm?3. The Mo1.33C MXene/PEDOT:PSS composite film shows a reduction in resistance upon H2SO4 treatment, a higher capacitance (1310 F cm?3) and improved rate capabilities than both pristine Mo1.33C MXene and the nontreated Mo1.33C/PEDOT:PSS composite films. The enhanced capacitance and stability are attributed to the synergistic effect of increased interlayer spacing between Mo1.33C MXene layers due to insertion of conductive PEDOT, and surface redox processes of the PEDOT and the MXene.  相似文献   

15.
Nonuniform local electric field and few nucleation sites on the reactive interface tend to cause detrimental lithium (Li) dendrites, which incur severe safety hazards and hamper the practical application of Li metal anodes in batteries. Herein, a carbon nanofiber (CNF) mat decorated with ultrafine titanium nitride (TiN) nanoparticles (CNF‐TiN) as both current collector and host material is reported for Li metal anodes. Uniform Li deposition is achieved by a synergetic effect of lithiophilic TiN and 3D CNF configuration with a highly conductive network. Theoretical calculations reveal that Li prefers to be adsorbed onto the TiN sheath with a low diffusion energy barrier, leading to controllable nucleation sites and dendrite‐free Li deposits. Moreover, the pseudocapacitive behavior of TiN identified through kinetics analysis is favorable for ultrafast Li+ storage and the charge transfer process, especially under a high plating/stripping rate. The CNF‐TiN‐modified Li anodes deliver lower nucleation overpotential for Li plating and superior electrochemical performance under a large current density (200 cycles at 3 mA cm?2) and high capacity (100 cycles with 6 mAh cm?2), as well as a long‐running lifespan (>600 h). The CNF‐TiN‐based full cells using lithium iron phosphate and sulfur cathodes exhibit excellent cycling stability.  相似文献   

16.
Lithium metal battery promises an attractively high energy density. A high Li-utilization rate of Li metal anode is the prerequisite for the high energy density and avoiding a huge waste of the Li resource. However, the dendritic Li deposition gives rise to “dead Li” and parasitic interfacial reactions, resulting in a low Li utilization rate. Herein, Li deposition is regulated to spherical Li by designing an MXene host with an egg-box structure, suitable curvature, and continuous gradient lithiophilic structure. Because the spherical Li greatly reduces the interfacial side reactions and avoids the formation of dead Li, the Li anode affords a high plating/stripping efficiency. Furthermore, the gradient lithiophilic design results in a bottom-up growth of the spherical Li within the host, safely away from the separator. Thus, the spherical Li anode realizes a long life of >3000 h with a high Li-utilization rate of >90%, stable cycling in full cells at an areal capacity up to 5 mAh cm−2 with a low negative/positive ratio of 0.8, which is critical for high energy density. Such spherical deposition highlights the critical role of the morphological control of alkali metals and provides a viable method to build practical high-energy metal batteries.  相似文献   

17.
Freestanding, robust electrodes with high capacity and long lifetime are of critical importance to the development of advanced lithium–sulfur (Li–S) batteries for next‐generation electronics, whose potential applications are greatly limited by the lithium polysulfide (LiPS) shuttle effect. Solutions to this issue have mostly focused on the design of cathode hosts with a polar, sulfurphilic, conductive network, or the introduction of an extra layer to suppress LiPS shuttling, which either results in complex fabrication procedures or compromises the mechanical flexibility of the device. A robust Ti3C2Tx/S conductive paper combining the excellent conductivity, mechanical strength, and unique chemisorption of LiPSs from MXene nanosheets is reported. Importantly, repeated cycling initiates the in situ formation of a thick sulfate complex layer on the MXene surface, which acts as a protective membrane, effectively suppressing the shuttling of LiPSs and improving the utilization of sulfur. Consequently, the Ti3C2Tx/S paper exhibits a high capacity and an ultralow capacity decay rate of 0.014% after 1500 cycles, the lowest value reported for Li–S batteries to date. A robust prototype pouch cell and full cell of Ti3C2Tx/S paper // lithium foil and prelithiated germanium are also demonstrated. The preliminary results show that Ti3C2Tx/S paper holds great promise for future flexible and wearable electronics.  相似文献   

18.
MXenes are a large class of 2D materials that consist of few-atoms-thick layers of transition metal carbides, nitrides, or carbonitrides. The surface functionalization of MXenes has immense implications for their physical, chemical, and electronic properties. However, solution-phase surface functionalization often leads to structural degradation of the MXene electrodes. Here, a non-conventional, single-step atomic surface reduction (ASR) technique is adopted for the surface functionalization of MXene (Ti3C2Tx) in an atomic layer deposition reactor using trimethyl aluminum as a volatile reducing precursor. The chemical nature of the modified surface is characterized by X-ray photoelectron spectroscopy and nuclear magnetic resonance techniques. The electrochemical properties of the surface-modified MXene are evaluated in acidic and neutral aqueous electrolyte solutions, as well as in conventional Li-ion and Na-ion organic electrolytes. A considerable improvement in electrochemical performance is obtained for the treated electrodes in all the examined electrolyte solutions, expressed in superior rate capability and cycling stability compared to those of the non-treated MXene films. This improved electrochemical performance is attributed to the increased interlayer spacing and modified surface terminations after the ASR process.  相似文献   

19.
3D scaffolds and heterogeneous seeds are two effective ways to guide Li deposition and suppress Li dendrite growth. Herein, 3D TiO2 nanotube (TNT) arrays decorated using ultrafine silver nanocrystals (7–10 nm) through cathodic reduction deposition are first demonstrated as a confined space host for lithium metal deposition. First, TiO2 possesses intrinsic lithium affinity with large Li absorption energy, which facilitates Li capture. Then, ultrafine silver nanocrystals decoration allows the uniform and selective nucleation in nanoscale without a nucleation barrier, leading to the extraordinary formation of lithium metal importing into 3D nanotube arrays. As a result, Li metal anode deposited on such a binary architecture (TNT-Ag-Li) delivers a high Coulomb efficiency at around 99.4% even after 300 cycles with a capacity of 2 mA h cm−2. Remarkably, TNT-Ag-Li exhibits ultralow overpotential of 4 mV and long-term cycling life over 2500 h with a capacity of 2 mAh cm–2 in Li symmetric cells. Moreover, the full battery with 3D spaced Li nanotubes anode and LiFeO4 cathode exhibits a stable and high capacity of 115 mA h g–1 at 5 C and an excellent Coulombic efficiency of ≈100% over 500 cycles.  相似文献   

20.
The lithium metal anode is one of the most promising anodes for next‐generation high‐energy‐density batteries. However, the severe growth of Li dendrites and large volume expansion leads to rapid capacity decay and shortened lifetime, especially in high current density and high capacity. Herein, a soft 3D Au nanoparticles@graphene hybrid aerogel (Au? GA) as a lithiophilic host for lithium metal anode is proposed. The large surface area and interconnected conductive pathways of the Au? GA significantly decrease the local current density of the electrode, enabling uniform Li deposition. Furthermore, the 3D porous structure effectively accommodates the large volume expansion during Li plating/stripping, and the LixAu alloy serves as a solid solution buffer layer to completely eliminate the Li nucleation over‐potential. Symmetric cells can stably cycle at 8 mA cm?2 for 8 mAh cm?2 and exhibit ultra‐long cycling: 1800 h at 2 mA cm?2 for 2 mAh cm?2, and 1200 h at 4 mA cm?2 for 4 mAh cm?2, with low over‐potential. Full cells assemble with a Cu@Au? GA? Li anode and LiFePO4 cathode, can sustain a high rate of 8 C, and retain a high capacity of 59.6 mAh g?1 after 1100 cycles at 2 C.  相似文献   

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