“…It was reported by the other groups that the intensity ratio can be regarded as an indicator of the ion mixing within the Li Slab, and a higher ratio of I (003) /I (104) represents a better degree of ordering in Li slab 6, 21 . Majumder, S. B 7 and Li, X 18 reported high performance NCA materials with intensity ratio of 1.28 and 1.12 respectively. In our approach, we prepared NCA cathode powder with maximum intensity ratio of 1.375 through such a simple routine, which is more advantageous compared with previous works and therefore good electrochemical performance is expectable.Figure 1( a ) XRD patterns of all the samples, ( b ) the relationship between the pressure and the value of I (003) /I (104) .
…”
Section: Resultsmentioning
confidence: 99%
“…The coating layer prevents the contact of the active material with the electrolyte. The Mg 2+ and F − doping can restrain the cationic mixing in a certain extent 15–18 . However, there are few ways to solve above problems at the same time by optimizing the synthesis method.…”
Sub-micron sized LiNi0.8Co0.15Al0.05O2 cathode materials with improved electrochemical performance caused by the reduced cationic disordering in Li slab were synthesized through a solid state reaction routine. In a typical process, spherical precursor powder was prepared by spray drying of a uniform suspension obtained from the ball-milling of the mixture of the starting raw materials. Then the precursor powders were pressed into tablets under different pressures and crushed into powder. The pressing treated powders were finally calcinated under oxygen atmosphere to obtain the target cathode materials. XRD investigation revealed a hexagonal layered structure without impurity phase for all samples and significant increase in the diffraction intensity ratio of I(003)/I(104) was observed. Rietveld refinement further confirmed the reduced cationic disordering in Li slab by such pressing treatment, and the smallest disordering was observed for sample S4 with only 1.3% Ni ions on Li lattice position. The electrochemical testing showed an improvement in electrochemical behavior for those pressing treated samples. The calculation of diffusion coefficients using EIS data showed improved Li diffusion coefficient after pressing treatment. The sample S4 presented a diffusion coefficient of 4.36 × 10−11 cm2·s−1, which is almost 3.5 times the value of untreated sample.
“…It was reported by the other groups that the intensity ratio can be regarded as an indicator of the ion mixing within the Li Slab, and a higher ratio of I (003) /I (104) represents a better degree of ordering in Li slab 6, 21 . Majumder, S. B 7 and Li, X 18 reported high performance NCA materials with intensity ratio of 1.28 and 1.12 respectively. In our approach, we prepared NCA cathode powder with maximum intensity ratio of 1.375 through such a simple routine, which is more advantageous compared with previous works and therefore good electrochemical performance is expectable.Figure 1( a ) XRD patterns of all the samples, ( b ) the relationship between the pressure and the value of I (003) /I (104) .
…”
Section: Resultsmentioning
confidence: 99%
“…The coating layer prevents the contact of the active material with the electrolyte. The Mg 2+ and F − doping can restrain the cationic mixing in a certain extent 15–18 . However, there are few ways to solve above problems at the same time by optimizing the synthesis method.…”
Sub-micron sized LiNi0.8Co0.15Al0.05O2 cathode materials with improved electrochemical performance caused by the reduced cationic disordering in Li slab were synthesized through a solid state reaction routine. In a typical process, spherical precursor powder was prepared by spray drying of a uniform suspension obtained from the ball-milling of the mixture of the starting raw materials. Then the precursor powders were pressed into tablets under different pressures and crushed into powder. The pressing treated powders were finally calcinated under oxygen atmosphere to obtain the target cathode materials. XRD investigation revealed a hexagonal layered structure without impurity phase for all samples and significant increase in the diffraction intensity ratio of I(003)/I(104) was observed. Rietveld refinement further confirmed the reduced cationic disordering in Li slab by such pressing treatment, and the smallest disordering was observed for sample S4 with only 1.3% Ni ions on Li lattice position. The electrochemical testing showed an improvement in electrochemical behavior for those pressing treated samples. The calculation of diffusion coefficients using EIS data showed improved Li diffusion coefficient after pressing treatment. The sample S4 presented a diffusion coefficient of 4.36 × 10−11 cm2·s−1, which is almost 3.5 times the value of untreated sample.
“…A wide range of dopants such as Al, Mg, Ti, Mo, Nb, and Na has been introduced into the nickel-rich cathode materials. [86][87][88][89][90][91][92][93][94][95][96][97][98] The mechanisms about improving the cathode stability from the doping was closely related to (1) the introduction of the electrochemically inactive elements into the host structure, (2) prevention of the undesired phase transition from the layered structure to the rock-salt like structure, and (3) promotion of the lithium ion transport due to increased lithium slab distance by the dopants. [21] Among many dopants, the Al and Mg are considered as the most appealing elements due to their low cost.…”
Section: Dopingmentioning
confidence: 99%
“…Representative approaches include the doping, [86][87][88][89][90][91][92][93][94][95][96][97][98] morphological control of the primary particle, [99][100][101][102][103][104] the cathode surface modification, [105][106][107][108][109][110] and the primary particle coating, [35,37,[111][112][113][114][115][116][117][118][119][120][121][122][123][124][125][126] which will be discussed below.…”
Section: Strategies To Realize Commercializationmentioning
practical candidate for the wide application of the LIBs with respect to the reversible capacity, rate capability, and capital cost. [4][5][6][7] In terms of nickel contents, the nickel-rich cathodes with nickel content above 80% have advantages in gravimetric capacity, allowing high gravimetric energy density, compared with the nickel content less than 80%. Currently, the nickel-rich cathodes with the amount of nickel less than 60% are fully commercialized. However, the nickel-rich cathodes with nickel content of ≥80% still have many difficulties in the commercialization with respect to powder properties and electrode fabrication process.The unstable powder properties originate from residual lithium compounds such as LiOH and Li 2 CO 3 that formed by the spontaneous reduction of sensitive trivalent nickel ions during the synthesis process and storage in air. [8][9][10][11] The Li 2 CO 3 significantly promotes the gas evolution and increase the moisture of the cathode powder, which strongly related to the safety issue. [12][13][14] Furthermore, the LiOH on the cathode increases the powder pH value, causing the gelation of the slurry during the electrode fabrication process. The nickel-rich cathode with nickel content of ≤60% have acceptable amount of residual lithium compounds for the practical use. By contrast, the cathode with amount of nickel of ≥80% should be treated by additional process to reduce the residual lithium compounds ( Table 1). Furthermore, other powder properties, such as powder pH and moisture, should be carefully controlled when nickel contents were exceeded of ≥80%. Thus, for the practical application of these cathode materials, most battery companies have adapted the washing process, in which the cathode power was stirred in purified water for 20-40 min. [15,16] The washing process could greatly reduce the residual lithium compounds and powder pH value. [15] However, the washing process not only increases process time and capital cost but also make the nickel-rich cathode more chemically sensitive than nonwashed cathodes. [16] More seriously, the water washing deteriorates the thermal stability of the nickel-rich cathodes, indicating that the washing process should be substituted by other methods for the battery safety.Another important factor for the commercialization of the nickel-rich cathodes is the electrode density directly related to the energy density. In general, the nickel-rich cathodesThe layered nickel-rich cathode materials are considered as promising cathode materials for lithium-ion batteries (LIBs) due to their high reversible capacity and low cost. However, several significant challenges, such as the unstable powder properties and limited electrode density, hindered the practical application of the nickel-rich cathode materials with the nickel content over 80%. Herein, important stability issues and in-depth understanding of the nickel-rich cathode materials on the basis of the industrial electrode fabrication condition for the commercialization of the nickel-rich cathode m...
“…To resolve these issues, different metals such as Co, Al, and Fe were studied as dopants/partial substitutes for Ni, which demonstrated promising but limited performance. Among these, Co and Al codoped LiNi 1−x−y Co x Al y O 2 (NCA, 0.05 ≤ ≤ 0.15, 0.01 ≤ ≤ 0.10) cathode materials exhibit the improved electrochemical properties and the thermal safety because cation substitution of Co and Al increases the stability of the structure [5,9]. However, a few drawbacks such as degradation during charge-discharge cycles and thermal runaway are yet to be resolved.…”
NCA (LiNi 0.85 Co 0.10 Al 0.05−x M x O 2 , M=Mn or Ti, < 0.01) cathode materials are prepared by a hydrothermal reaction at 170 ∘ C and doped with Mn and Ti to improve their electrochemical properties. The crystalline phases and morphologies of various NCA cathode materials are characterized by XRD, FE-SEM, and particle size distribution analysis. The CV, EIS, and galvanostatic charge/discharge test are employed to determine the electrochemical properties of the cathode materials. Mn and Ti doping resulted in cell volume expansion. This larger volume also improved the electrochemical properties of the cathode materials because Mn
4+and Ti 4+ were introduced into the octahedral lattice space occupied by the Li-ions to expand the Li layer spacing and, thereby, improved the lithium diffusion kinetics. As a result, the NCA-Ti electrode exhibited superior performance with a high discharge capacity of 179.6 mAh g −1 after the first cycle, almost 23 mAh g −1 higher than that obtained with the undoped NCA electrode, and 166.7 mAh g −1 after 30 cycles. A good coulombic efficiency of 88.6% for the NCA-Ti electrode is observed based on calculations in the first charge and discharge capacities. In addition, the NCA-Ti cathode material exhibited the best cycling stability of 93% up to 30 cycles.
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