Abstract: The present application provides a positive electrode and a lithium-ion battery. The positive electrode comprises a current collector; a first active material layer comprising a first active material; and a second active material layer; wherein the first active material layer is arranged between the current collector and the second active material layer, the first active material layer comprises a first active material, and the first active material is at least one selected from a group consisting of a modified lithium transition metal oxide positive electrode material and a modified lithium iron phosphate. The positive electrode of the present application helps to improve the thermal stability of the lithium-ion battery, and the improvement of the thermal stability may reduce the proportion of the thermal runaway when the lithium-ion battery is internally short-circuited so that the safety performance of the lithium-ion battery is improved.

Abstract: The present disclosure relates to a fracturing propping agent and a preparation method thereof. The fracturing propping agent comprises the following raw materials: dry sludge, quartz sand, coal ash, bauxite and clay.

Abstract: The present disclosure relates to a fracturing propping agent and a preparation method thereof. The fracturing propping agent comprises the following raw materials: dry sludge, quartz sand, coal ash, bauxite and clay.

Abstract: A cationic copolymer represented by the following formula (I) has a viscosity average molecular weight in a range from 2 million to 10 million. In the cationic copolymer, the mole fractions of three structural units corresponding to three monomers are as follows: x being in a range from 0.01 to 20%, y being in a range from 0 to 15%, and z=1?x?y. When used in the construction of leaking stoppage in an oil well, a cationic chemical lost circulation additive prepared with the cationic copolymer is mixed with an anionic drilling fluid in a section of the wellbore where lost circulation occurs. Then neutral reaction and cross linking reaction occur, so that the viscosity of the resulting mixture rapidly increases to form a space grid structure. This blocks off the leakage path, and thus effects on efficient leaking stoppage in a short time period.

Abstract: A cationic copolymer represented by the following formula (I) has a viscosity average molecular weight in a range from 2 million to 10 million. In the cationic copolymer, the mole fractions of three structural units corresponding to three monomers are as follows: x being in a range from 0.01 to 20%, y being in a range from 0 to 15%, and z=1?x?y. When used in the construction of leaking stoppage in an oil well, a cationic chemical lost circulation additive prepared with the cationic copolymer is mixed with an anionic drilling fluid in a section of the wellbore where lost circulation occurs. Then neutral reaction and cross linking reaction occur, so that the viscosity of the resulting mixture rapidly increases to form a space grid structure. This blocks off the leakage path, and thus effects on efficient leaking stoppage in a short time period.

Abstract: A copolymer and preparation method and application thereof are disclosed. The copolymer is random copolymer obtained from monomers consisting of acrylamide, acrylic acid, alkenyl sulfonate, 2-acrylamido-dodecyl sulfonate, p-styrene sulfonate or isoprene sulfonate and so on. The copolymer of present invention can be used as fluid loss additive and has good fluid loss properties, which would not make the drilling fluid thicken at high temperature of 200° C. and high salt conditions of saturated brine. It has a medium-pressure fluid loss after aging and rolling for 16 h at high temperature of 200° C., as measured in accordance with the American Petroleum Institute Standard Test at room temperature, and has good properties of high temperature-resisting and salt-resisting.

Abstract: A copolymer and preparation method and application thereof are disclosed. The copolymer is random copolymer obtained from monomers consisting of acrylamide, acrylic acid, alkenyl sulfonate, 2-acrylamido-dodecyl sulfonate, p-styrene sulfonate or isoprene sulfonate and so on. The copolymer of present invention can be used as fluid loss additive and has good fluid loss properties, which would not make the drilling fluid thicken at high temperature of 200° C. and high salt conditions of saturated brine. It has a medium-pressure fluid loss after aging and rolling for 16 h at high temperature of 200° C., as measured in accordance with the American Petroleum Institute Standard Test at room temperature, and has good properties of high temperature-resisting and salt-resisting.

Abstract: An electropositive and water-based production well treating fluid system exhibits electropositivity by using a cationic viscosifier meanwhile matched with a cationic fluid loss additive and, optionally, contains a mud-building agent, an electrical stabilizing agent, a colloid-stabilizing agent, lubricant, an oil layer protective agent and/or a weighting agent. The electropositive production well treating fluid can beffer solve the contradiction of technical requirements between “treating fluid stability” and “bore hole stability”, and features a strong ability to inhibit the dispersion of clay, a good effect of protecting oil-gas reservoirs, fast drilling speeds, regular shape of bore holes and good resistance to salt.

Abstract: The present invention provides an electropositive and water-based production well treating fluid system. The production well treating fluid system can be made to exhibit electropositivity by using a cationic viscosifier meanwhile matched with a cationic fluid loss additive and optionally matched with a mud-building agent, electrical stabilizing agent, colloid-stabilizing agent, lubricant, oil layer protective agent and/or weighting agent. Such kind of electropositive production well treating fluid can solve better the contradiction between “treating fluid stability” and “bore hole stability”, and has features in strong ability of inhibiting the dispersion of clay, good effect of protecting oil-gas reservoir, fast drilling speed, regular shape of bore hole and good resistance to salt. The present invention relates further to a method of preparing said production well treating fluid system and use of the drilling fluid and well completion fluid in petroleum drilling and well completion.