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Recently, niobium tungsten oxide has garnered considerable attention owing to its excellent Li-ion diffusion rate and prominent structural stability during charge–discharge cycles. Here, a cathode material (LiNi0.8Co0.1Mn0.1O2, NCM811) for Li-ion batteries is successfully coated with Li-ion conductive Li2.09W0.9Nb0.1O4 using a simple wet-chemical c...
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In this study, we present a method for synthesizing Ni-rich LiNi0.93Co0.04Al0.03O2 (NCA) with a high-energy cathode material by the solid-phase method. The sintering temperature plays a very important role in the electrochemical performance of the LiNi0.93Co0.04Al0.03O2 since it affects the crystallinity and structural stability. Therefore, various...
Citations
... All Nyquist diagrams consist of a semicircle and an oblique straight line. The semicircle in the high frequency region is related to the charge transfer process (R ct ) on the surface of the material, while the slope in the low frequency region corresponds to the Warburg diffusion process [38,39]. The corresponding equivalent circuit diagram is located in the corresponding impedance spectrum, where R s represents the impedance of the electrolyte, R ct is the charge transfer impedance, CPE represents the interfacial double layer capacitance, and W represents the Warburg impedance [40,41]. ...
LiNi0.6Co0.2Mn0.2O2 cathode material has been widely studied by researchers due to its high capacity, but its further development is restricted by low rate capacity, poor interface stability, and poor structural stability. Nb-Cl co-doped LiNi0.6Co0.2Mn0.2O2 cathode materials were prepared by solid-phase method. Structural analysis revealed that Nb and Cl elements were uniformly incorporated into the crystal structure. Electrochemical results show that the optimal co-doping amounts of Nb and Cl are 1% and 2%, and the modified LiNi0.6Co0.2Mn0.2O2 cathode material exhibits higher discharge capacity and cycle stability. At 0.5 C, the capacity retention rate was 90.80% after 100 cycles at a cut-off voltage of 3.0–4.6 V, much higher than that of the pristine sample which was 81.17%. In addition, the modified sample can still maintain a reversible capacity of 148.0 mAh g⁻¹ even at 5 C. This is attributed to the synergistic effect of anion-cation co-doping, which effectively inhibits the phase transition process on the surface of the material in a highly delithiated state, slows down the structural collapse during cycling, and promotes the reversible intercalation/extraction of Li⁺. EIS and GITT tests also proved that Nb-Cl co-doping reduces the charge transfer resistance (Rct) and effectively increases the lithium ion diffusion rate.
... All Nyquist diagrams consist of a semicircle and an oblique straight line. The semicircle in the high frequency region is related to the charge transfer process (R ct ) on the surface of the material, while the slope in the low frequency region corresponds to the Warburg diffusion process [28,29] . The corresponding equivalent circuit diagram is located in the corresponding impedance spectrum, where R s represents the impedance of the electrolyte, R ct is the charge transfer impedance, CPE represents the interfacial double layer capacitance, and W 1 represents the Warburg impedance [30,31] . ...
LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode material has been widely studied by researchers due to its high capacity, but its further development is restricted by low rate capacity, poor interface stability and poor structural stability. Nb-Cl co-doped LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode materials were prepared by co-precipitation method. Structural analysis revealed that Nb and Cl elements were uniformly incorporated into the crystal structure. Electrochemical results show that the optimal co-doping amounts of Nb and Cl are 1% and 2%, and the modified LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode material exhibits higher discharge capacity and cycle stability. At 0.5 C, the capacity retention rate was 90.80% after 100 cycles at a cut-off voltage of 3.0-4.6 V, much higher than that of the pristine sample which was 81.17%. In addition, the modified sample can still maintain a reversible capacity of 148.0 mAh g − 1 even at 5 C. This is attributed to the synergistic effect of anion-cation co-doping, which effectively inhibits the phase transition process on the surface of the material in a highly delithiated state, slows down the structural collapse during cycling, and promotes the reversible intercalation/extraction of Li ⁺ . EIS and GITT tests also proved that Nb-Cl co-doping reduces the charge transfer resistance R ct and effectively increases the lithium ion diffusion rate.
... For the S-NCM sample, the peaks at 855.3 eV and 861.0 eV are attributed to Ni 2p1/2 and the corresponding satellite peak, while for the C-NCM sample, the peaks at 855.4 eV and 861.2 eV are attributed to Ni 2p1/2 and corresponding satellite peak. After fitting the peak of Ni 2p [37][38][39][40][41], the Ni 2+ percentage of S-NCM (854.7 eV) is 65.62%, while that of C-NCM (854.7 eV) is 69.58%. These findings are consistent with XRD results. ...
... For the S-NCM sample, the peaks at 855.3 eV and 861.0 eV are attributed to Ni 2p 1/2 and the corresponding satellite peak, while for the C-NCM sample, the peaks at 855.4 eV and 861.2 eV are attributed to Ni 2p 1/2 and corresponding satellite peak. After fitting the peak of Ni 2p [37][38][39][40][41], the Ni 2+ percentage of S-NCM (854.7 eV) is 65.62%, while that of C-NCM (854.7 eV) is 69.58%. These findings are consistent with XRD results. ...
This work introduces a one-step method for the preparation of layered oxide cathode materials utilizing pure Ni and Co mixed solution obtained from the waste hydrodesulfurization (HDS) catalyst. An efficient non-separation strategy with pyrometallurgical-hydrometallurgical (pyro-hydrometallurgical) process consisting of roasting and leaching is proposed. Most of the impurity metal elements such as Mo and V were removed by simple water leaching after the waste HDS catalyst was roasted with Na2CO3 at 650 °C for 2.5 h. Additionally, 93.9% Ni and 100.0% Co were recovered by H2SO4 leaching at 90 °C for 2.5 h. Then, LiNi0.533Co0.193Mn0.260V0.003Fe0.007Al0.004O2 (C–NCM) was successfully synthesized by hydroxide co-precipitation and high temperature solid phase methods using the above Ni and Co mixed solution. The final C–NCM material exhibits excellent electrochemical performance with a discharge specific capacity of 199.1 mAh g−1 at 0.1 C and a cycle retention rate of 79.7% after 200 cycles at 1 C. This novel process for the synthesis of cathode material can significantly improve production efficiency and realize the high added-value utilization of metal resources in a waste catalyst.
... For layered materials with extremely high Ni contents, trace element doping is not enough to minimize the defects caused by Ni-rich crystal structures. Coating is a modification strategy that can not only protect the cathode material from erosion of HF in electrolytes [31][32][33][34] but also strengthen the engineered strength of secondary particles to maintain the morphological integrity at the depth cycle. However, the difference between the physical and chemical properties of the coating layer and the bulk material is too large to allow them to form an obvious phase interface. ...
In this study, a Co-rich Ni-rich layered material with a core-shell structure is designed, in which LiNi0.82Co0.12Mn0.06O2 (NCM-Ni82) is used as the core wrapped in the shell by doping Al into LiNi0.735Co0.15Mn0.1Al0.015O2 to form the hybrid particle LiNi0.795Co0.13Mn0.07Al0.005O2 (NCM-HA). NCM-HA is divided modularly into the core part NCM-Ni82 and the single hybrid part without doped Al (NCM-HS), and then all modules were compared with the pristine LiNi0.8Co0.1Mn0.1O2 via various characterization methods to reveal the superiority of the design. The core-shell structure, which prevents the diffusion of microcracks caused by the lattice shrinkage of a high content of cobalt, is used to improve the morphological strength of the material so that the cathode material is capable of fully playing the excellent stable cycling performance brought by the remarkable cationic order degree of Co-rich treatment. The excellent cathode material NCM-HA still has a capacity retention rate of 83.3 5% after 200 cycles, while the pristine material has a rate of 55.42%. Moreover, NCM-HA successfully inhibits the unsteady phase transition of layered materials at 4.2 V and reduces the degree of polarization during the cycling process. This study provides a new strategy for the modification of Cobalt-enriched Ni-rich layered materials.
... The lithium batteries' current demands are mainly the higher energy density (> 300 Wh/kg), longer cycle life, and higher thermal stability, and the cathode materials play a crucial role in lithium-ion batteries. In recent years, among the many cathode materials, the nickel-rich nickel-cobalt-manganese ternary material (LiNi 1-x-y Co x Mn y O 2 ) [5][6][7][8][9] has become a research hotspot because of its high energy density and low cost, especially for the LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) [10][11][12]. However, the practical and large-scale application of NCM811 has been hindered by the severe safety problem due to the thermal runaway (especially charged to a high cutoff voltage) and capacity fading, which results from the structural instability caused by the Li + /Ni 2+ cation mixing. ...
Achieving a highly stable structure is the key to successfully enhancing the cycling stability and safety performance of LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material for Li-ion batteries at a high cutoff voltage (4.5 V). In this work, the co-precipitation method is applied to prepare the precursor of the full concentration gradient (FCG) NCM811, and Mg2+ is doped into bulk phase to prepare LiNi0.8-xCo0.1Mn0.1MgxO2 (x = 0.01, 0.02, 0.03, and 0.04) for modification. Influences of magnesium doping direction and magnitude on electrochemical performance are investigated. It is found that Li(Ni0.8Co0.1Mn0.1)1-xMgxO2 shows low Li+/Ni2+ cation mixing in the voltage of 2.7–4.5 V with high structural stability and improves cycling stability because of the pillaring effect of inactive Mg in the crystal structure. In terms of the doping direction, compared with the uniform magnesium doping material, the specific discharge capacity with a forward concentration gradient doping is increased by 5.96%, and the cycle stability can be promoted as high as 6.33%. For the magnitude of the doping concentration gradient, the specific discharge capacity compared to pristine (Ni0.8Co0.1Mn0.1O2) material can be increased by 10.1%, and correspondingly the cycle stability can be promoted as high as 13.7%. After doping 3% Mg2+ with the optimal forward concentration gradient direction and cycling for 200 cycles at 2.7 ~ 4.5 V and 1 C, the specific discharge capacity is up to 163.5 mAh/g, and the capacity retention rate can keep 82.99%. Additionally, LiNi0.8Co0.1Mn0.1O2 doped with 3% Mg2+ along the forward concentration gradient direction has a positive effect on reducing the material impedance.
