Nickel-rich cathode materials are widely used for electronic devices because of their high capacity and rate performance. However, structural deterioration after long-term cycling leads to a significant decline in capacity and cycle life. In this work, the effects of three different cations doping on the structural stability and electrochemical performance of Ni-rich cathode materials were investigated. XRD characterization reveals that doped cation leads to broadening of the distance between Li layers and inhibiting Li + /Ni 2+ mixing arrangement. Compared with Na + and K + , the high valence Mg 2+ provides a stronger Mg-O bond, which can effectively restrain the undesired phase transition and sustain the ordered structure. Electrochemical tests demonstrate that NCA with Mg doping has better cycle stability and rate performance than Na and K. The capacity retention rate of NCA with 1% Mg doping is 87.7% after 200 cycles at 1C, and it can still provide a specific capacity of 146.8 mAh g −1 at a high rate of 5C.
Cadmium oxides (CdO), an important semiconductor material , have many superior properties when used as a cathode material for nickel-cadmium batteries. Here, the coating and the doped co-modified LiNi 0.8 Co 0.15 Al 0.05 O 2 cathode are constructed by a continuous wet chemical process and a high-temperature sintering process, wherein the Cd 2+ are uniformly doped in a gradient form and the CdO protective layer is distributed on the outer surface of secondary particles. The Cd-modified NCA material has more stable interfacial and crystal lattice structure, thereby inhibiting harmful phase transitions and side-reactions. Accordingly, the modified sample has excellent electrochemical performance and maintaining a complete spherical morphology during long cycling compared to the pristine sample. In addition, as a pillar ion, cadmium increases the plate spacing and lithium-ion diffusion kinetics. The electrochemical results show that the capacity retention of the modified sample Cd-2000 reached 96.5% and 90.6% after 100 cycles and 200 cycles respectively at 1 C. At the high current rate of 8 C, the initial capacity and retention (100 cycles, 3.0–4.3 V) reach 166.2 mAh g −1 and 95.2%, respectively. Besides, the results of electrochemical impedance spectroscopy (EIS) reveal that CdO modification could decrease the resistance of the cell polarization and impedance increment upon cycling.
Layered transition metal hydroxide, a clay-like material, possessing characteristics of large specific surface area, adjustable fraction, and plentiful active components make it a potential energy storage material , especially in the background of energy and environment crisis. Herein, comprehensive applications of cobalt-aluminum-based LDHs for supercapacitors are proposed. Binder-free electrodes were successfully synthesized such as Co 3 Al 1 -LDH/Ni, Ni 2 Co 1 Al 1 -LDH/Ni and Ni 1 Co 2 Al 1 -LDH/Ni using a rapid green hydrothermal approach. Subsequently, further sulfuration was carried out to obtain a heterostructure of sulfide/layered hydroxide. The electrochemical energy storage properties of binder-free electrodes were investigated, which show that the performance of ternary LDH electrode is better than that of binary one, and the incompletely sulfuration Ni 1 Co 2 S/Ni has the optimal electrochemical performance among all electrodes, with a specific capacitance of 2186 F g −1 at 1 A g −1 . The Ni 1 Co 2 S//AG hybrid supercapacitor (HSC) device assembled with Ni 1 Co 2 S as positive electrode and active graphene as negative electrode delivers an energy density of 13 Wh kg −1 at a power density of 749 W kg −1 , good rate capability and cycling stability.
危险品化学品经营许可证（带存储）