ABSTRACT
Li[Ni0.8Co0.15Al0.05]O2 (NCA) is a cathode material for lithium-ion batteries and has high power density and capacity. However, this material has disadvantages such as structural instability and short lifespan. To address these issues, herein, we explore the impact of N-doped carbon wrapping on NCA. Sericin, an easily obtained carbon- and nitrogen-rich component of silk cocoons, is utilized as the precursor material. The electrochemical performance evaluation of N-doped carbon-coated NCA shows that the capacity retention of 0.3 NC@NCA at 1C current density is 69.83% after 200 cycles, which is about 19% higher than the 50.65% capacity retention of bare NCA. The results reveal that the sericin-resultant N-doped carbon surface wrapping improves the cycling stability of NC@NCA.
ABSTRACT
Sodium-ion batteries (SIBs) have emerged as an alternative candidate in the field of energy storage applications. To achieve the commercial success of SIBs, the designing of active materials is highly important. O3-type layered-NaFe0.5Mn0.5O2 (NFM) materials provide higher specific capacity along with Earth-abundance and low cost. Nevertheless, the material possesses some disadvantages, such as a low rate capability and severe capacity fading during cycling. To overcome such drawbacks, composite O3-type layered NFM with carbon has been prepared for the cathode electrode of SIBs through a facile solution combustion method followed by calcination process. The introduction of carbon sources into NFM material provides excellent electrochemical performances; moreover, the practical limitations of NFM material such as low electrical conductivity, structural degradation, and cycle life are effectively controlled by introducing carbon sources into the host material. The NFM/C-2 material delivers the specific charge capacities of 171, 178, and 166 mA h g-1; and specific discharge capacities of 188, 169, and 162 mA h g-1, in the first 3 cycles, respectively.
ABSTRACT
Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) is regarded as a potential cathode material due to its higher capacity. However, the severe capacity fading which occurs above 4.2 V vs. Li/Li+ needs to be addressed to enhance the electrochemical performance. Herein, we report the surface modification of NCM811 cathodes with a perovskite material, i.e., lanthanum iron oxide (LaFeO3), which has drawn attention for various research areas due to its non-toxicity, electric conductivity, chemical stability, and low cost and systematically investigate the influence of the LaFeO3 coating on NCM811. The LaFeO3 coating layer significantly protects the cathode material from corrosion due to the HF formation and restrains the dissolution of other ions into liquid electrolyte during high voltage charge-discharge processes. Even after 80 cycles, 0.5 wt% LaFeO3-coated NCM811 cathode material shows about 13% higher cycling stability when compared to the bare NCM811 and other ratios of coated materials. Furthermore, the 0.5 wt% LaFeO3-coated NCM811 delivers excellent rate capability and demonstrates improved structural stability at 4.6 V vs. Li/Li+ under high voltage conditions with Ni-rich cathode active materials.
