Sulfide-based all-solid-state lithium-ion batteries (ASSLIBs) are promising candidates in the next generation of energy storage technology; the voltage mismatch and the resulting side reactions at the interface between the cathode...

The LiCoO 2 (LCO) cathode has been widely used in material markets, especially in conventional lithium ion batteries, due to its stable electrochemical performance. Increasing the working cutoff potential represents an efficient pathway to boost the capacity of LCO batteries; however, high working potentials usually induce severe Co 3+ dissolution and extensive growth of solid electrolyte interphase (SEI) layer, leading to rapid degradation of the electrochemical performance. In this work, a high voltage cathode is prepared by the encapsulation of aluminum (Al)-doped LiCoO 2 in a continuous Li 4 Ti 5 O 12 (LTO) layer using a high-speed solid-phase coating method. The chemical composition evolution of the coating layer during the cycling process was characterized and evaluated through in situ XRD, XPS, and XAS analyses. The precipitation of aluminum fluoride (AlF 3 ) at the defective sites of the LTO coating layer in the initial charge−discharge cycles effectively was found to fortify the structural integrity of the coating layer and prevent the etching of the LCO from undesirable side reactions with the liquid electrolyte. The modified LCO demonstrated an excellent capacity retention of 89.9% after 100 cycles at 0.2 C. The high-speed solid-phase coating method established in this study could be scaled up straightforwardly, providing a highly commercializable approach for large-scale production of stable high-voltage LCO cathode materials. KEYWORDS: high-voltage LiCoO 2 , Li 4 Ti 5 O 12 , solid-phase coating, long-term stability, in situ XRD

Change regulation of the physical properties of fluid is key to accurately predicting multiphase fluid flow in the production wellbore of CO2 flooding reservoirs. Given the characteristics of significant changes in pressure, temperature, and CO2 content in the whole wellbore of production wells in CO2 flooding reservoirs, this paper systematically studied the change rules of volume factor, viscosity, density, and solubility of well fluid for pressure 5~30 MPa, temperature 20~120 °C, and CO2 content 10~90% through single degassing PVT experiments. According to the experimental results, the volume factor of crude oil increases first and then decreases with the pressure increase. At the bubble point pressure (20 MPa), the volume factor of crude oil can reach 1.89 at high temperatures. The volume factor can be increased from 1.28 to 1.44 at 8 MPa when the temperature increases from 20 °C to 120 °C. Under the bubble point pressure, the increase in pressure increases the solubility of CO2, and the viscosity of crude oil decreases rapidly. In contrast, above the saturation pressure, the increase in pressure increases the viscosity of crude oil. Under the freezing point temperature (24 °C), the viscosity of crude oil decreases sharply with increase in temperature. In contrast, above the freezing point temperature, the viscosity change of crude oil is not sensitive to temperature. The wellbore temperature has a significant impact on the density of the well fluid. At 5 MPa, the temperature increases from 20 °C to 120 °C, which can reduce the density of high CO2 crude oil from 0.93 g/cm3 to 0.86 g/cm3. The solubility of CO2 in crude oil is sensitive to pressure. When the pressure increases from 5 MPa to 15 MPa at 20 °C, the solubility increases by 36.56 cm3/cm3. The results of this paper support the multiphase fluid flow law prediction of CO2 flooding production wells with a high gas–liquid ratio.