Realizing the single-crystalline LiNi 0.90 Mn 0.05 Co 0.05 O 2 cathode with long-life and high-safety property driven by polysiloxane covering and PO43- doping

As a promising cathode for lithium-ion batteries, the ultra-high nickel content layered oxide LiNi0.90Co0.05Mn0.05O2 demonstrates the great attention for the high discharging capacity. However, the serious capacity attenuation resulted from the instable interface, crystal structure degeneration and strong side-reactions on cathode-electrolyte interphase with charging-discharging drastically restricts its extensive application. To alleviate the intrinsic drawbacks, the combination improvement strategy for polysiloxane covering and PO43- doping is adopted to lower the surface residual alkali amounts, defend the HF/F- attacking and enhance the cation location order of LiNi0.90Co0.05Mn0.05O2. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) are used to evaluate the synthesized samples. The cathodes after the polysiloxane covering and PO43- doping deliver the improved crystal structure, larger lattice parameters and superior electrochemical properties. The polysiloxane coated and PO43- doped sample exhibits a high discharging capacity of 147.5 mAh g(-1) at 10.0C rate and 155.4 mAh g(-1) at -30 degrees C, remains a capacity of 193.2 mAh g(-1) at 1.0C after 300 cycles with a retention of 91.2 %. Besides, when applied in pouch full batteries, it could pass the rigorous safety tests of Bar impact, Overcharging test and Nail penetration successfully, and still maintain the superior cycling stability in practice application.