首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
Li[NixCoyMnz]O2 (NCM) layered materials have been successfully adopted in commercial lithium ion batteries (LIBs). The presence of higher Ni content in cathode materials helps to improve the capacity. However, increased cation mixing on the surface of layered material leads to unstable structure. Aluminium (Al) doping is known to enhance the performance of cathode material by rendering thermal and structural stability. In this article, we synthesize Li[Ni0.8Co0.1Mn0.1]O2 (Bare NCM811) and Li[Ni0.78Co0.1Mn0.1Al0.02]O2 (Al-Doped NCM811) using simple co-precipitation process followed by calcination process. The electrochemical, morphological, and structural characteristics of the Al-Doped NCM811 are investigated and compared with the Bare NCM811. The discharge capacity of the Bare NCM811 and the Al-Doped NCM811 maintained 73.59% and 96.15% after the 100th cycle at a room temperature of 20?°C and 87.32% and 94.38% after the 50th cycle at an elevated temperature of 60?°C, respectively. The enhanced electrochemical performance of Al-Doped NCM811 is attributed to the improved thermal and structural properties of the electrode, as confirmed using differential scanning calorimeter (DSC) and particle compression tester (PCT).  相似文献   

2.
It is still a huge challenge to improve the safety and stability of Ni-rich (LiNi0.8Co0.1Mn0.1O2) cathode materials at elevated potential. Herein, the PrF3 layer is employed to protect LiNi0.8Co0.1Mn0.1O2 (NCM811) via a simple wet chemical process. It was confirmed by XRD, HR-SEM, TEM, EDS, and XPS tests that PrF3 is evenly covered throughout the surface of NCM811 without affecting the particle size and surface morphology. In particular, 1 wt% PrF3 coated NCM811 exhibits excellent stability and rate capability with the capacity retention of 86.3% after 100 cycles at 1 C under a cut-off potential of 4.3 V, while the retention of pristine one is only 73.8%. Moreover, the capacity retention of 1 wt% PrF3 coated samples enhances from 74.5% to 88.5% after 50 cycles at 1 C under higher cut-off voltage of 4.6 V. The superior performance for coated samples can be attributed to the fact that PrF3 can effectively isolate the active material and the electrolyte from HF corrosion, and at the same time, reduce the generation of micro-cracks on the surface during prolonged cycles. Furthermore, as a physical barrier, PrF3 alleviates the dissolution of transition metals in the electrolyte largely. These results suggest that the stability of NCM811 can be greatly upgraded at high voltage by PrF3 coating.  相似文献   

3.
《Ceramics International》2019,45(11):13942-13950
The Ni-rich LiNi0.8Co0.1Mn0.1O2 layered oxide (NCM811) is attracting considerable attention as a high-capacity cathode material for rechargeable Li-ion batteries. However, due to its inherent structural/chemical/electrochemical instability, NCM811 with high Ni content suffers from significant performance degradation upon storage even in ambient atmospheres as well as during charge–discharge cycling. Herein, we demonstrate a simple but effective surface-tuning approach to mitigate storage-induced degradation of NCM811, which is based on the conversion of undesirable Li residues to a protective Li3PO4 nanolayer via phosphate treatment. The accelerated storage stability test shows that phosphate-modified NCM811 exhibits remarkably improved electrochemical performance (capacity, cycle life, and rate capability) over the pristine one after being stored under harsh environmental conditions. A combined analytical study indicates that surface tuning through phosphate treatment enhances the storage stability of NCM811 by eliminating impurity-forming Li residues and producing a Li3PO4 nanolayer that inhibits parasitic reactions at the electrode–electrolyte interface. Furthermore, Li3PO4 provides an effective barrier to H2O and CO2 infiltration into the particle agglomerates, thereby suppressing the loss of particle integrity.  相似文献   

4.
《Ceramics International》2022,48(7):9124-9133
The main obstacles in lithium-ion battery are limited by rate performance and the rapid capacity fading of LiNi0.8Co0.1Mn0.1O2 (NCM811). Herein, a novel three-dimensional (3D) hierarchical coating material has been fabricated by in situ growing carbon nanotubes (CNTs) on the surfaces of Ni–Al double oxide (Ni–Al-LDO) sheets (named as LDO&CNT) with Ni–Al double hydroxide (Ni–Al-LDH) as both the substrate and catalyst precursor. The resultant LDO&CNT nanocomposites are uniformly coated on the surfaces of NCM811 by the physical mixing method. The rate capability of the resultant cathode material retains to 78.80% at a current rate of 3C. Its capacity retention increases by 6.7–14.42% compared with pristine NCM811 after 100 cycles within a potential range of 2.75–4.3 V at 0.5C. The improved rate capability and cycle performance of NCM811 are assigned to the synergistic effects between Ni–Al-LDO and CNTs. The hierarchical LDO&CNT nanocomposites coating on the surface of NCM811 avoids the aggregation of conductive CNTs and the stacking of Ni–Al-LDO nanosheets. Furthermore, it accelerates Li+ and electrons shuttle and reduces the reaction of Li2O with H2O and CO2 in air, which results in Li2CO3 and LiOH alkali formation on the NCM811 surface.  相似文献   

5.
《Ceramics International》2023,49(1):443-449
All-solid-state lithium batteries (ASSLBs), which are consisted of Li5.5PS4.5Cl1.5 electrolyte, metal lithium anode and LiNi0.8Mn0.1Co0.1O2 (NCM811) cathode, are speculated as a promising next generation energy storage system. However, the unstable oxide cathode/sulfide-based electrolyte interface and the dendrite formation in sulfide electrolyte using the lithium metal anode hinder severely commercialization of the ASSLBs. In this work, the dendrite formation in sulfide electrolyte is investigated in lithium symmetric cell by varying the stack pressure (3, 6, 12, 24 MPa) during uniaxial pressing, and uniformly nanosized LiAlO2 buffer layer was carefully coated on NCM811 electrode (LiAlO2@NCM811) to improve the cathode/electrolyte interface stability. The result shows that lithium symmetrical cell has a steady voltage evolution over 400 h under 6 MPa stacking pressure, and the assembled LiAlO2@NCM811/Li5.5PS4.5Cl1.5/Li battery under the stack pressure of 6 MPa exhibits large initial discharge specific capacity and excellent cycling stability at 0.05 C and 25 °C. The feasibility of using the lithium metal anode in all-solid-state batteries (ASSBs) under suitable stack pressure combined with uniformly nanosized LiAlO2 buffer layer coated on NCM811 electrode supply a facile and effective measures for constructing ASSLBs with high energy density and high safety.  相似文献   

6.
《Ceramics International》2023,49(10):15842-15850
Lithium-ion batteries are widely used in aerospace, power vehicles, portable electronic devices and other fields because of their environmental friendliness, rechargeable cycle and high energy density. The nickel-cobalt-manganese ternary materials with high nickel has high specific discharge capacity and is regarded as one of the most promising cathode materials. However, with the increase of the number of cycles, the cycle performance becomes worse and the specific capacity decays sharply. In this work, Al2O3 and LiAlO2 were coated on the surface of NCM811 by combining ball milling mixing and solid-phase synthesis to prepare the AL-NCM811 cathode material. The coating thickness formed by Al2O3 and LiAlO2 was 10–70 nm, which effectively improves the cycle stability and rate performance of NCM811 material. When charged and discharged at 0.1C, the first discharge specific capacity and capacity retention rate after 100 cycles of 0.5AL-NCM811 were 196.26 mAh/g and 96.47%, respectively, while those of NCM811 were only 193.78 mAh/g and 72.18%, respectively. When the current density was 5.0C, the discharge specific capacity of 0.5AL-NCM811(139.16 mAh/g) was 55.368 mAh/g higher than that of NCM811(83.80 mAh/g).  相似文献   

7.
《Ceramics International》2020,46(14):21888-21901
LiNi0.8Co0.1Mn0.1O2 (NCM811) is a typical nickel (Ni)-rich ternary cathode material with several advantages, such as high specific capacity, low-cost, and environmentally friendly, making it a good candidate for use in lithium-ion batteries. However, its Ni content is as high as 80%; therefore, several new problems have emerged with gradually increasing applications. In this review, Li–Ni disorder and corresponding modification methods are first briefly reviewed, and then the origin of complex surface defect, which has a crippling effect on diffusion processes of Li+ at electrolyte/cathode interface, is discussed in detail. Analyses showed the importance of selecting appropriate surface modification material/technique for enhancing electrochemical properties. Therefore, popular surface coating materials and methods including metal oxides, fluorides, phosphates, fast ion conductors, and other compounds/elements used for the development of NCM811 are subjected to extensive and thorough research. Finally, several new perspectives and insights related to stability and safety at high voltages and temperatures, and the optimization of production process are also proposed.  相似文献   

8.
The nacre-inspired Al-Si/TiB2 composites were successfully prepared by freeze casting and pressure infiltration. The microstructures and mechanical properties of nacre-inspired Al-Si/TiB2 composites were studied by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and mechanical testing. The results show that the high performance of Al-Si/TiB2 composites can be attributed to the clean interfaces between TiB2 and Al and several toughening mechanisms, such as crack blunting, crack branching, crack deflection, plastic deformation of Al layer, and bridging of the uncracked fracture process zone. Specifically, the compressive strength, three-point bending strength and KIC of composites corresponding to LS were 640–710 MPa, 629 MPa, and 16.4 MPa m1/2, respectively. The fracture behaviors of the Al-Si/TiB2 composites have been discussed in detail in this work. It was found that single cracks were accompanied by the propagation of multiple micro-cracks in the layered composites. The precipitation of Si particles at the TiB2/α-Al interface and the Al phases infiltrated in the TiB2 layers play a great role in the formation of single crack fractures and multiple micro-cracks fractures, respectively, in the nacre-inspired Al-Si/TiB2 composites.  相似文献   

9.
《Ceramics International》2023,49(5):7956-7964
Single crystalline ternary cathode material LiNi0.5Co0.2Mn0.3O2(NCM523) can operate at extremely high voltages and could offer exceptional energy density. The single crystal morphology is less easy to form the cracks and could express better structure stability compared to the polycrystalline counterpart. However, irreversible parasitic side reactions in the interface during cycling may lead to rapid electrochemical degradations. Herein, a simple chemical wet method that modifies the single-crystal NCM523 particles with Al2O3 coating is proposed. The coating layer can effectively suppress the phase transformation and irreversible phase transition on the NCM surface during cycling. Furthermore, the cladding layer can prevent the erosion of by-products such as HF. As a result, the Al2O3 modified NCM523 delivers a high specific capacity of 192.5mAh g?1, excellent cycling stability and rate capability. The capacity retention was 91.7% after 50 cycles even at ultra-high cut-off voltage of 4.7 V. This surface engineering strategy paves the way to promote the development of small size single crystal NCM523 materials for next generation LIBs.  相似文献   

10.
《Ceramics International》2020,46(4):4643-4651
Particle size plays an important role in the electrochemical properties of cathode materials for lithium-ion battery, and the sizes of cathode powders are often designed to specific scales to obtain desired rate capacity, cyclic stability, etc. Nano-sized or micron-sized primary/secondary particles were both reported to be helpful to heighten the electrochemical properties of the same material system. However, the relationship between particle size and electrochemical properties of Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM-811) has not been discussed in detail. Here, we prepared the pristine NCM-811 powders with various micro-sized particles by using solid state reaction, and investigated the influence of particle size on the electrochemical properties of typical NCM-811 cathode material, to clarify the importance of size effect. The result indicates that pristine NCM-811 cathode powders with D50 = 7.7 μm displayed the best initial discharge specific capacity (224.5 and 169.1 mA h/g at 1/20 C and 1 C rate, respectively) and retention capacity (71.0% at 1 C rate) after 100th cycling at room temperature. The mutual acting mechanism in terms of layered structure, cation mixing degree, polarization state, charge-transfer resistance, and the diffusion ability of lithium-ion was confirmed by XRD, XPS, CV and EIS analyses, respectively.  相似文献   

11.
《Ceramics International》2023,49(19):31485-31495
In this paper, LiNi0.8Co0.1Mn0.1O2 (NMC811) thin films were prepared by the sol-gel method based on different parameter conditions, and the microstructure and electrochemical properties of the films were compared to obtain the film sample under the best preparation parameters. In order to explain the formation mechanism of cell battery performance based on the NMC811 cathode at the nano scale, electrochemical strain microscopy, conductive atomic force microscopy and Kelvin probe force microscopy are specifically utilized to study the changes of NMC811 thin film in electrochemical deformation, conductivity, and potential distribution under different electrical and thermal fields. The results indicate that the local amplitude, conductivity, and electrical potential of thin film in the scanning region increases with the voltage from 0 V to 3 V and the temperature from 25 °C to 150 °C. However, the electrochemical deformation, conductivity, and potential of the film decrease significantly when the voltage is applied to 4 V or the temperature rises to 200 °C.These results provide visual evidence for the influence of external field on the phase structure change and lithium-ion diffusion behavior of NMC811 thin film.  相似文献   

12.
《Ceramics International》2017,43(17):15173-15178
LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode has been modified by incorporating ZrO2 nanoparticles to improve its electrochemical performance. Compared to the pristine electrode, the cycling stability and rate capability of 0.5 wt% ZrO2 modified-NCM622 have been improved significantly. The 0.5 wt% ZrO2 modified-NCM622 cathode shows a capacity retention of 83.8% after 100 cycles at 0.1 C between 2.8 and 4.3 V, while that of the pristine NCM622 electrode is only 75.6%. When the current rate is set as 5C, the capacity retention of the 0.5 wt% ZrO2-modified NCM622 is 10% higher than that of the pristine NCM622. Also, the rate capability of 0.5 wt% ZrO2-modified NCM622 is better than that of the pristine NCM622 at various C-rates in a voltage range of 2.8–4.3 V. The enhanced electrochemical performances of the ZrO2-modified NCM622 cathodes can be attributed to their high Li-ion conductivity and structural stability.  相似文献   

13.
Lithium-ion based rechargeable batteries are considered among the most promising battery technologies because of the high energy- and power-densities of these electrochemical devices. Computational studies on lithium ion batteries (LIBs) facilitate rationalization and prediction of many important experimentally observed properties, including atomic structure, thermal stability, electronic structure, ion diffusion pathways, equilibrium cell voltage, electrochemical activity, and surface behavior of electrode materials. In recent years, Ni, Co and Mn-based (NCM) layered transition metal oxide positive electrode materials (LiNi1-x-yCoxMnyO2) have shown tremendous promise for high-energy density LIBs, and these NCM-based batteries are effectively commercialized. Here, we present an overview of recent theoretical work performed using first principles density functional theory on these layered cathode materials. This short review focuses on recent computational efforts of popular NCMs with increasing Ni content, ranging from NCM333 to NCM811.  相似文献   

14.
《Ceramics International》2020,46(14):22606-22618
This study aimed to prepare a composite coating material comprising a solid ionic conductor of lithium aluminum titanium phosphate (Li1.4Al0.4Ti1.6(PO4)3, LATP) and porous carbon through a sol-gel method. LiNi0.8Co0.1Mn0.1O2 (LNCM811) cathode material with dual-functional composite conductors (i.e., LATP@porous carbon), denoted as LATP-PC, was prepared. The dry-coating method, also called the “mechanical-fusion alloy route,” was used to modify Ni-rich LNCM811 cathode materials. X-ray diffraction (XRD), micro-Raman spectroscopy, and X-ray photoelectron spectroscopy confirmed that the LATP ionic conductor generated herein was uniformly deposited on 3D porous carbon and served as a dual-functional composite coating on LNCM811. Furthermore, the capacity retention of LATP-PC@LNCM811 was approximately 85.57% and 80.86% after 100 cycles at −20 °C and 25 °C, respectively. By contrast, pristine LNCM811 had the capacity retention of 78% and 74.96% at −20 °C and 25 °C, respectively. Furthermore, the high-rate capability of the LATP-PC@LNCM811 material was markedly enhanced to 169.81 mAh g−1 at 10C relative to that of pristine LNCM811, which was approximately 137.67 mAh g−1. The electrochemical performance of LNCM811 was enhanced by the uniform dual-conductive composite coating. The results of the study indicate that the LATP-PC@LNCM811 composite material developed herein is a potentially promising material for future high-energy Li-ion batteries.  相似文献   

15.
《Ceramics International》2020,46(13):20985-20992
The surface coating strategy provide a facile and effective means of improving the electrochemical behavior of lithium-ion batteries (LiBs) since it can prevent cathodes/anodes from contacting moisture and improve the thermal stability and cyclability of LiBs. However, to date, few studies have focused on carbon coating Ni-rich cathodes due to the moisture sensitivity of cathode materials. Herein, poly (vinylidene fluoride)/n-vinyl-2-pyrrolidinone (PVDF/NMP) solution was employed as the carbon source to coat LiNi0.8Mn0.1Co0.1O2 (NMC811) spheres for the first time. The coating process mainly includes two steps under moisture-free conditions: (1) wetting NMC811 using PVDF/NMP solution and (2) heat treatment of NMC811/PVDF under inert circumstances. The thickness of the obtained carbon layer can be controlled easily by adjusting the solution concentration. A 2.5 wt% PVDF containing solution can coat a carbon layer of ~4 nm on NMC811 spheres, which significantly improved the integral Li+ storage performance. The discharge capacity of the resulting carbon-coated NMC811 showed only a 1.26% decrease after 100 cycles at a 0.2 C rate, while pristine NMC811 lost 6.85% of its initial reversible capacity. This work highlights that carbon coating offers a facile yet effective approach to achieve high-performance cathodes materials for LIBs.  相似文献   

16.
《Ceramics International》2021,47(21):30266-30272
During the preparation process of LiNi0·6Co0·2Mn0·2O2 (NCM622) material via solid-phase method, the obtained NCM622 particle size is often inconsistent due to the inhomogeneous phase mixing, which makes the NCM622 material have low specific capacity and poor rate performance, and thus restrict the application of solid-phase method. In order to solve this problem and make full use of the advantages of solid-phase method, liquid-phase assisted mixing is used to replace the traditional mechanical mixing. At the same time, polyvinylpyrrolidone (PVP) is introduced to control the crystal morphology and particle size, thus a NCM622 material with excellent electrochemical energy storage performance has been prepared by the PVP modified liquid-phase assisted solid-state method in this paper. X-ray diffraction, scanning electron microscopy and Raman spectroscopy are used to characterize the morphology structure of the obtained materials. Their electrochemical energy storage performance is tested by program-controlled battery tester and electrochemical workstation after being assembled into button cells. The research results show that with the introduction of PVP, the particle size of the obtained material becomes smaller, the particle size distribution is more uniform, and the degree of cation mixing is further reduced. When the PVP adding amount is up to 1.6 wt %, the obtained material shows the best electrochemical performance: its first discharge specific capacity and coulomb efficiency are 183.19 mAh.g−1 and 88 % (0.1C), respectively. The capacity retention rate is 96.5 % after 100 cycles at 1C (half-cell system and laboratory conditions), which is comparable or better than those by other preparation methods, showing a good application prospect.  相似文献   

17.
All-solid-state cells (ASSCs) typically operate at a specific pressure to ensure good contact between the solid electrolyte and the electrode-active materials. However, establishing the ideal cell pressure is challenging because of the various cell structures, the mechanical characteristics of solid electrolytes, and the extent to which the volume of the electrodes changes during cycling. In this study, we propose a specially designed cell assembly that adjusts to the changes in volume that occur during cycling while maintaining a constant cell pressure. The evaluations indicate that the spring in the cell assembly effectively reduces the stress incurred from the volume expansion that occurs in the electrode during charging (lithiation) and the volume contraction that occurs during discharging (delithiation) while maintaining the prescribed cell pressure. The capacity fading—as a function of the cycle number—decreases when operating ASSCs comprising a cell assembly that include a spring, compared with those that exclude a spring. Focused ion beam–scanning electron microscope reveals no cracks and delamination in the LiNi0.8Co0.1Mn0.1O3 (NCM811) composite cathode of the ASSCs, operated at 25 MPa, with a spring-equipped assembly. The Ag nanolayer that deposits on the Cu foil is an effective collector metal, forming a dense lithium plating layer on the Ag/Cu foil anode.  相似文献   

18.
The Ni-rich LiNi0.83Co0.12Mn0.05O2 (NCM83) cathode materials have drawn intensive attention due to the high energy density and low cost. However, Ni-rich LiNi1-x-yCoxMnyO2 still has the fatal weakness of poor cycle stability, limiting its further wide application. Bulk doping is an effective means to enhance the cycle stability, yet the electrochemical performances are very sensitive to the doping quantity. Here a facile method of co-precipitation is adopted to coat (Ni0.4Co0.2Mn0.4)1-xAlx(OH)2+x on precursor particles of NCM83. Al ions diffuse evenly in the NCM83 particles after sintering. The cells are operated at a high cut-off voltage of 4.5 V. The discharge capacity of NCM83 is 187.8 mAh g?1, and decays fast with cycles. The doped sample even exhibits a higher discharge capacity of 195 mAh g?1, and the capacity retention is improved to 83.8% after 200 cycles.  相似文献   

19.
《Ceramics International》2022,48(3):3397-3403
The high-Ni layered metal oxide, LiNi0.8Co0.1Mn0.1O2 (LNCM811), has received widespread attention in the energy field because of its high specific capacity, but its large-scale applications are hindered due to severe capacity fading. Herein, a uniform and thin Li2O–B2O3–LiBr-glass (LBBrO-glass) coating was deposited on LNCM811 by a liquid-phase coating and thermal treatment method. The experimental results suggested that the LBBrO-glass coating acted as a protective layer that inhibited transition metal dissolution and side reactions, which helped improve the electrochemical properties of LNCM811. Remarkably, after 200 cycles, the 2 wt% coating (LBBrO@LNCM-2) delivered a superior capacity retention of 88.9%, while only 71.8% was obtained for the pristine material (LNCM811). The discharge capacity of LBBrO@LNCM-2 was 163.5 mAh g?1 at 5C, while it was only 139 mAh g?1 for the pristine material.  相似文献   

20.
《Ceramics International》2022,48(21):31598-31605
A strategy to enhance the electrochemical performance of a single-crystal LiNixMnyCozO2 (NCM) electrode is proposed herein based on a preferred orientation of a Li diffusion pathway along the working direction under an ordinary 0.4-T magnetic field. Hexagonal NCM622 single crystals can be aligned along their crystallographic c-axis parallel to the applied magnetic field because the crystal has an easy magnetization axis along the c-axis. The horizontal magnetic field–oriented NCM622 cathode (HMFC) shows inhibited polarization and increased lithium-ion conductivity. The suppressed polarization promotes cyclability, increasing the specific capacity from 157.93 to 168.75 mAhg?1 after the 100th cycle at 0.5 C. Furthermore, the increased diffusion coefficient (from 3.06 × 10?10 cm2s?1 to 7.12 × 10?10 cm2s?1) causes substantial improvement in the rate performance, achieving a high specific capacity of 130.77 mAhg?1 at 10 C, while the electrode without magnetic treatment achieves a specific capacity of only 115.88 mAhg?1. Owing to such a superior electrochemical performance, the HMFC electrodes show high potential for lithium-ion batteries in the EV industry. Decreasing the magnetic field from 6 to 0.4 T for cathode alignment facilitates the applicability of the proposed strategy to production lines of battery plants using commercially available permanent magnets because a magnetic field of 0.4 T is easily achievable.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号