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1.
    
Electrode-electrolyte reactivity (EER) and particle cracking (PC) are considered two main causes of capacity fade in high-nickel layered oxide cathodes in lithium-based batteries. However, whether EER or PC is more critical remains debatable. Herein, the fundamental correlation between EER and PC is systematically investigated with LiNiO2 (LNO), the ultimate cobalt-free lithium layered oxide cathode. Specifically, EER is found more critical than secondary particle cracking (SPC) in determining the cycling stability of LNO; EER leads to primary particle cracking, but mitigates SPC due to the inhibition of H2-H3 phase transformation. Two surface degradation pathways are identified for cycled LNO under low and high EERs. A common blocking surface reconstruction layer (SRL) containing electrochemically-inactive Ni3O4 spinel and NiO rock-salt phases is formed on LNO in an electrolyte with a high EER; in contrast, an electrochemically-active SRL featuring regions of electron- and lithium-ion-conductive LiNi2O4 spinel phase is formed on LNO in an electrolyte with a low EER. These findings unveil the intrinsic degradation pathways of LNO cathode and are foreseen to provide new insights into the development of lithium-based batteries with a minimized EER and a maximized service life.  相似文献   

2.
    
Promoting the interfacial Li+ transport and suppressing detrimental lithium dendrites are the main challenges for developing practical solid-state lithium metal batteries. In this respect, interface rationalizing to synergize the enhancement of ion transport and suppression of lithium dendrites is of paramount significance. Herein, a novel strategy is demonstrated to address those issues by a designed multifunctional composite interlayer. The photocrosslinkable polymer is introduced in a scalable elastic skeleton, which promotes the migration and diffusion of Li+. Moreover, adding perfluoropolyether in the interlayer benefits to regulating the formation of LiF-rich interface, sufficiently suppress the growth of lithium dendrites. Benefitting from the elasticity, high Li+ conductivity and the lithium dendrites suppression capability, the interlayer can significantly improve the interfacial performance of the solid electrolyte/lithium interface, thus leading to the greatly enhanced electrochemical performance of solid-state lithium metal batteries. A high critical current density of 3.6 mA cm−2 and a long cycling life at 1.0 mA cm−2 for >400 h are achieved for the symmetric cells. Besides, when used in a pouch-type full cell coupled with LiNi0.6Co0.2Mn0.2O2 cathode, a high charged capacity of 3.25 mAh cm−2 can be maintained through 20 cycles, demonstrating its great potentials for practical application.  相似文献   

3.
    
Lithium metal batteries (LMBs) working at subzero temperatures are plagued by severe restrictions from the increased energy barrier of Li-ion migration and desolvation. Herein, a competitive coordination strategy based on the ternary-anion (TA) coupling of PF6, TFSI, and NO3 toward Li+ to achieve an anti-freezing electrolyte with rapid kinetics is proposed. Computational and spectroscopic analyses reveal that the repulsive interaction among three anions and the preponderant coordination of the Li+-NO3 further weaken the involvement degree of other anions in the Li+ solvation structure. As a result, the formulated TA electrolyte exhibits low binding energy of Li+-anions (−4.62 eV), Li+ desolvation energy (17.04 kJ mol−1), and high ionic conductivity (3.39 mS cm−1 at −60 °C), simultaneously promoting anion-derived solid electrolyte interphase on Li anode. Assembled Li||LiNi0.8Co0.1Mn0.1O2 cells employing the TA electrolyte exhibit robust capacity retention of 86.74% over 200 cycles at 25 °C and deliver a specific cathode capacity of 103.85 mAh g−1 at −60 °C. This study will enlighten the rational design of multi-anion electrolytes to tailor the Li+ solvation/desolvation for advanced low-temperature LMBs.  相似文献   

4.
    
Solid-state lithium metal batteries (SSLMBs) are a promising candidate for next-generation energy storage systems due to their intrinsic safety and high energy density. However, they still suffer from poor interfacial stability, which can incur high interfacial resistance and insufficient cycle lifespan. Herein, a novel poly(vinylidene fluoride‑hexafuoropropylene)-based polymer electrolyte (PPE) with LiBF4 and propylene carbonate plasticizer is developed, which has a high room-temperature ionic conductivity up to 1.15 × 10−3 S cm−1 and excellent interfacial stability. Benefitting from the stable interphase, the PPE-based symmetric cell can operate for over 1000 h. By virtue of cryogenic transmission electron microscopy (Cryo-TEM) characterization, the high interfacial compatibility between Li metal anode and PPE is revealed. The solid electrolyte interphase is made up of an amorphous outer layer that can keep intimate contact with PPE and an inner Li2O-dominated layer that can protect Li from continuous side reactions during battery cycling. A LiF-rich transition layer is also discovered in the region of PPE close to Li metal anode. The feasibility of investigating interphases in polymer-based solid-state batteries via Cryo-TEM techniques is demonstrated, which can be widely employed in future to rationalize the correlation between solid-state electrolytes and battery performance from ultrafine interfacial structures.  相似文献   

5.
    
Sodium metal batteries are promising for cost-effective energy storage, however, the sluggish ion transport in electrolytes and detrimental sodium-dendrite growth stall their practical applications. Herein, a cross-linking quasi-solid electrolyte with a high ionic conductivity of 1.4 mS cm−1 at 25 °C is developed by in-situ polymerizing poly (ethylene glycol) diacrylate-based monomer. Benefiting from the refined solvation structure of Na+ with a much lower desolvation barrier, random Na+ diffusion on the Na surface is restrained, so that the Na dendrite formation is suppressed. Consequently, symmetrical Na||Na cells employing the electrolyte can be cycled >2000 h at 0.1 mA cm−2. Na3V2(PO4)3||Na batteries reveal a high discharge specific capacity of 66.1 mAh g−1 at 15 C and demonstrate stable cycling over 1000 cycles with a capacity retention of 83% at a fast rate of 5 C.  相似文献   

6.
    
Garnet structured ceramic electrolyte Li7La3Zr2O12 (LLZO) attracts much attention in solid-state lithium batteries for its high ionic conductivity, wide electrochemical window, and lack of reducible element. However, the application of LLZO has been hindered by severe dendrite penetration. The theoretical investigations on the mechanisms of lithium dendrite evolution are carried out, aiming at quantifying the promotion effects of overpotential and the limitation counterpart of bulk modulus. Since dendrites preferentially propagate along connected defects, while intrinsic defects are difficult to be compeletely eliminated, manipulation of overpotential should be a more feasible way for dendrites suppression. The mixed electronic-ionic conducting interphase, which in situ forms by introducing a Ti-doping Li56La24Zr15TiO96 (T-LLZO) interlayer between Li and LLZO, is suggested based on the proposed mechanisms, which effectively facilitates to alleviate the overpotential thus suppress the lithium dendrites theoretically. This strategy is verified experimentally by obviously improved stability of Li/Li symmetric cell using T-LLZO ceramic pellet electrolyte.  相似文献   

7.
    
A molten lithium infusion strategy has been proposed to prepare stable Li‐metal anodes to overcome the serious issues associated with dendrite formation and infinite volume change during cycling of lithium‐metal batteries. Stable host materials with superior wettability of molten Li are the prerequisite. Here, it is demonstrated that a series of strong oxidizing metal oxides, including MnO2, Co3O4, and SnO2, show superior lithiophilicity due to their high chemical reactivity with Li. Composite lithium‐metal anodes fabricated via melt infusion of lithium into graphene foams decorated by these metal oxide nanoflake arrays successfully control the formation and growth of Li dendrites and alleviate volume change during cycling. A resulting Li‐Mn/graphene composite anode demonstrates a super‐long and stable lifetime for repeated Li plating/stripping of 800 cycles at 1 mA cm?2 without voltage fluctuation, which is eight times longer than the normal lifespan of a bare Li foil under the same conditions. Furthermore, excellent rate capability and cyclability are realized in full‐cell batteries with Li‐Mn/graphene composite anodes and LiCoO2 cathodes. These results show a major advancement in developing a stable Li anode for lithium‐metal batteries.  相似文献   

8.
    
A major hurdle to the successful deployment of high‐energy‐density lithium metal based batteries is dendrite growth during battery cycling, which raises safety and cycle life concerns. Coating the Li metal anode with a soft polymer layer has been previously shown to be effective in suppressing dendrite growth, leading to uniform lithium deposition even at high current densities. A 3D coarse‐grained molecular model to study the mechanism of dendrite suppression is presented. It is found that the most effective coatings delay or even prevent dendrites from penetrating the polymer layer during deposition. The optimal deposition can be achieved by jointly tuning the polymer stiffness and relaxation time. Higher polymer dielectric permittivity and coating thickness are also effective, but the deposition rate and, therefore, the charging current density is reduced. These findings provide the basis for rational design of soft polymer coatings for stable lithium deposition.  相似文献   

9.
    
Tailoring inorganic components of cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) is critical to improving the cycling performance of lithium metal batteries. However, it is challenging due to complicated electrolyte reactions on cathode/anode surfaces. Herein, the species and inorganic component content of the CEI/SEI is enriched with an objectively gradient distribution through employing pentafluorophenyl 4-nitrobenzenesulfonate (PFBNBS) as electrolyte additive guided by engineering bond order with functional groups. In addition, a catalytic effect of LiNi0.6Mn0.2Co0.2O2 (NCM622) cathode is proposed on the decomposition of PFBNBS. PFBNBS with lower highest occupied molecular orbital can be preferentially oxidized on the NCM622 surface with the help of the catalytic effect to induce an inorganic-rich CEI for superior electrochemical performance at high voltage. Moreover, PFBNBS can be reduced on the Li surface due to its lower lowest unoccupied molecular orbital , increasing inorganic moieties in SEI for inhibiting Li dendrite generation. Thus, 4.5 V Li||NCM622 batteries with such electrolyte can retain 70.4% of initial capacity after 500 cycles at 0.2 C, which is attributed to the protective effect of the excellent CEI on NCM622 and the inhibitory effect of its derived CEI/SEI on continuous electrolyte decomposition.  相似文献   

10.
    
Lithium (Li) metal is one of the most promising candidates for the anode in high‐energy‐density batteries. However, Li dendrite growth induces a significant safety concerns in these batteries. Here, a multifunctional separator through coating a thin electronic conductive film on one side of the conventional polymer separator facing the Li anode is proposed for the purpose of Li dendrite suppression and cycling stability improvement. The ultrathin Cu film on one side of the polyethylene support serves as an additional conducting agent to facilitate electrochemical stripping/deposition of Li metal with less accumulation of electrically isolated or “dead” Li. Furthermore, its electrically conductive nature guides the backside plating of Li metal and modulates the Li deposition morphology via dendrite merging. In addition, metallic Cu film coating can also improve thermal stability of the separator and enhance the safety of the batteries. Due to its unique beneficial features, this separator enables stable cycling of Li metal anode with enhanced Coulombic efficiency during extended cycles in Li metal batteries and increases the lifetime of Li metal anode by preventing short‐circuit failures even under extensive Li metal deposition.  相似文献   

11.
    
The electrode/electrolyte interface plays a critical role in stabilizing the cycling performance and prolonging the service life of rechargeable batteries to meet the sustainable energy requirements of the mobile society. The understanding of interfaces is still at the preliminary stage due to the limited research techniques and variable properties with time and potential. Herein, the latest developments focused on the interfaces in rechargeable systems including the cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) are reviewed. The possible formation mechanisms of the electrode/electrolyte interface are discussed, followed by the introduction of two key influencing factors, specific adsorption and solvated coordinate structure, which will dominate the formation of the interface. Finally, the structure and chemical composition of the interface as well as the possible transport mechanism of lithium ions in the interface and the strategies to regulate the pathway through the interface are presented in detail. This work sheds light on the fundamental understanding of the interface and provides rational scientific principles in designing the electrode/electrolyte interface and inspires the rational design of long‐term cycling rechargeable batteries.  相似文献   

12.
    
Construction of high efficiency and stable Li metal anodes is extremely vital to the breakthrough of Li metal batteries. In this study, for the first time, groundbreaking in situ plasma interphase engineering is reported to construct high-quality lithium halides-dominated solid electrolyte interphase layer on Li metal to stabilize & protect the anode. Typically, SF6 plasma-induced sulfured and fluorinated interphase (SFI) is composed of LiF and Li2S, interwoven with each other to form a consecutive solid electrolyte interphase. Simultaneously, brand-new vertical Co fibers (diameter: ≈5 µm) scaffold is designed via a facile magnetic-field-assisted hydrothermal method to collaborate with plasma-enhanced Li metal anodes (SFI@Li/Co). The Co fibers scaffold accommodates active Li with mechanical integrity and decreases local current density with good lithiophilicity and low geometric tortuosity, supported by DFT calculations and COMSOL Multiphysics simulation. Consequently, the assembled symmetric cells with SFI@Li/Co anodes exhibit superior stability over 525 h with a small voltage hysteresis (125 mV at 5 mA cm−2) and improved Coulombic efficiency (99.7%), much better than the counterparts. Enhanced electrochemical performance is also demonstrated in full cells with commercial cathodes and SFI@Li/Co anode. The research offers a new route to develop advanced alkali metal anodes for energy storage.  相似文献   

13.
    
Lithium metal (LM) is a promising anode material for next generation lithium ion based electrochemical energy storage devices. Critical issues of unstable solid electrolyte interphases (SEIs) and dendrite growth however still impede its practical applications. Herein, a composite gel polymer electrolyte (GPE), formed through in situ polymerization of pentaerythritol tetraacrylate with fumed silica fillers, is developed to achieve high performance lithium metal batteries (LMBs). As evidenced theoretically and experimentally, the presence of SiO2 not only accelerates Li+ transport but also regulates Li+ solvation sheath structures, thus facilitating fast kinetics and formation of stable LiF-rich interphase and achieving uniform Li depositions to suppress Li dendrite growth. The composite GPE-based Li||Cu half-cells and Li||Li symmetrical cells display high Coulombic efficiency (CE) of 90.3% after 450 cycles and maintain stability over 960 h at 3 mA cm−2 and 3 mAh cm−2, respectively. In addition, Li||LiFePO4 full-cells with a LM anode of limited Li supply of 4 mAh cm−2 achieve capacity retention of 68.5% after 700 cycles at 0.5 C (1 C = 170 mA g−1). Especially, when further applied in anode-free LMBs, the carbon cloth||LiFePO4 full-cell exhibits excellent cycling stability with an average CE of 99.94% and capacity retention of 90.3% at the 160th cycle at 0.5 C.  相似文献   

14.
    
Ionic liquid (IL) electrolytes with concentrated Li salt can ensure safe, high‐performance Li metal batteries (LMBs) but suffer from high viscosity and poor ionic transport. A locally concentrated IL (LCIL) electrolyte with a non‐solvating, fire‐retardant hydrofluoroether (HFE) is presented. This rationally designed electrolyte employs lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 1‐methyl‐1‐propyl pyrrolidinium bis(fluorosulfonyl)imide (P13FSI) and 1,1,2,2‐tetrafluoroethyl 2,2,3,3‐tetrafluoropropyl ether (TTE) as the IL and HFE, respectively (1:2:2 by mol). Adding TTE enables a Li‐concentrated IL electrolyte with low viscosity and good separator wettability, facilitating Li‐ion transport to the Li metal anode. The non‐flammability of TTE contributes to excellent thermal stability. Furthermore, synergy between the dual (FSI/TFSI) anions in the LCIL electrolyte can help modify the solid electrolyte interphase, increasing Li Coulombic efficiency and decreasing dendritic Li deposition. LMBs (Li||LiCoO2) employing the LCIL electrolyte exhibit good rate capability (≈89 mAh g?1 at 1.8 mA cm?2, room temperature) and long‐term cycling (≈80% retention after 400 cycles).  相似文献   

15.
16.
In solid polymer electrolytes (SPEs) based Li–metal batteries, the inhomogeneous migration of dual-ion in the cell results in large concentration polarization and reduces interfacial stability during cycling. A special molecular-level designed polymer electrolyte (MDPE) is proposed by embedding a special functional group (4-vinylbenzotrifluoride) in the polycarbonate base. In MDPE, the polymer matrix obtained by copolymerization of vinylidene carbonate and 4-vinylbenzotrifluoride is coupled with the anion of lithium-salt by hydrogen bonding and the “σ-hole” effect of the C F bond. This intermolecular interaction limits the migration of the anion and increases the ionic transfer number of MDPE (tLi+ = 0.76). The mechanisms of the enhanced tLi+ of MDPE are profoundly understood by conducting first-principles density functional theory calculation. Furthermore, MDPE has an electrochemical stability window (4.9 V) and excellent electrochemical stability with Li–metal due to the CO group and trifluoromethylbenzene (ph-CF3) of the polymer matrix. Benefited from these merits, LiNi0.8Co0.1Mn0.1O2-based solid-state cells with the MDPE as both the electrolyte host and electrode binder exhibit good rate and cycling performance. This study demonstrates that polymer electrolytes designed at the molecular level can provide a broader platform for the high-performance design needs of lithium batteries.  相似文献   

17.
    
Solid-state lithium metal batteries (SSLMBs) have gained extensive attraction as one kind of next-generation energy storage device. However, the drawbacks of flammability, low mechanical strength, and low ionic conductivity limit the further development of solid-state polymer electrolytes (SPEs). In this work, a reactive flame-retardant unit into the polymer framework via covalent bonding to create a nonflammable and stretchable polyurethane-based SPEs is introduced. Meanwhile, the mechanical strength of the polymer backbone is increased by grafting a rigid benzene ring unit, which remarkably suppresses the lithium-dendrite growth. As a result, these inflammable SPEs do not burn after contact with flames for 6 s. Furthermore, the obtained SPE expands the electrochemical stability window up to 5.1 V. Small monomers containing bromine decompose on the surface of lithium metal creating a LiBr riched solid electrolyte interface (SEI). Li|SPEs|Li symmetric battery offers a stable cycling life for more than 2100 h at 0.2 mA cm−2 and 0.2 mAh cm−2. The LiNi0.6Co0.2Mn0.2O2|SPEs|Li cell equipped with the integrated cathode delivers a 142.1 mAh g−1 capacity after 330 cycles at 0.3 C with 85.2% capacity retention.  相似文献   

18.
Effective utilization of Li-metal electrodes is vital for maximizing the specific energy of lithium–oxygen (Li–O2) batteries. Many conventional electrolytes that support Li–O2 cathode processes (e.g., dimethyl sulfoxide, DMSO) are incompatible with Li-metal. Here, a wide range of ternary solutions based on solvent, salt, and ionic liquid (IL) are explored to understand how formulations may be tailored to enhance stability and performance of DMSO at Li-metal electrodes. The optimized formulations therein facilitate stable Li plating/stripping performances, Columbic efficiencies >94%, and improved performance in Li–O2 full cells. Characterization of Li surfaces reveals the suppression of dendritic deposition and corrosion and the modulation of decomposition reactions at the interface within optimized formulations. These observations are correlated with spectroscopic characterization and simulation of local solvation environments, indicating the persistent importance of DMSO–Li+-cation interactions. Therein, stabilization remains dependent on important molar ratios in solution and the 4:1 solvent-salt ratio, corresponding to ideal coordination spheres in these systems, is revealed as critical for these ternary formulations. Importantly, introducing this stable, non-volatile IL has negligible disrupting effects on the critical stabilizing interactions between Li+ and DMSO and, thus, may be carefully introduced to tailor other key electrolyte properties for Li–O2 cells.  相似文献   

19.
    
For the development of all-solid-state lithium metal batteries (LMBs), a high-porous silica aerogel (SA)-reinforced single-Li+ conducting nanocomposite polymer electrolyte (NPE) is prepared via two-step selective functionalization. The mesoporous SA is introduced as a mechanical framework for NPE as well as a channel for fast lithium cation migration. Two types of monomers containing weak-binding imide anions and Li+ cations are synthesized and used to prepare NPEs, where these monomers are grafted in SA to produce SA-based NPEs (SANPEs) as ionomer-in-framework. This hybrid SANPE exhibits high ionic conductivities (≈10−3 S cm−1), high modulus (≈105 Pa), high lithium transference number (0.84), and wide electrochemical window (>4.8 V). The resultant SANPE in the lithium symmetric cell possesses long-term cyclic stability without short-circuiting over 800 h under 0.2 mA cm−2. Furthermore, the LiFePO4|SANPE|Li solid-state batteries present a high discharge capacity of 167 mAh g−1 at 0.1 C, good rate capability up to 1 C, wide operating temperatures (from −10 to 40 °C), and a stable cycling performance with 97% capacity retention and 100% coulombic efficiency after 75 cycles at 1 C and 25 °C. The SANPE demonstrates a new design principle for solid-state electrolytes, allowing for a perfect complex between inorganic silica and organic polymer, for high-energy-density LMBs.  相似文献   

20.
金属锂负极具有极高的比容量、极低的密度和最负的电势,被认为是最有希望的下一代高能量密度型电池的负极材料。然而,在反复充放电过程中,锂负极会出现严重的粉化和枝晶生长,造成安全隐患,极大地降低了电池的性能,缩短了使用寿命。综述了近年来国内外针对金属锂负极存在问题进行的改性研究进展,从锂负极存在问题的根源、锂枝晶的生长模式以及近年来改善锂负极的举措三个方面出发,重点针对锂枝晶问题开展分析,并予以展望,为高能量密度锂电池的商业化研究提供借鉴。  相似文献   

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