509 results about "Concentration polarization" patented technology

The invention relates to a high-water-flux forward-osmosis composite membrane and a preparation method thereof. The forward-osmosis composite membrane is a polysulfone-sulfonated polysulfone-inorganic filler blended / polyamide composite membrane. A traditional osmosis membrane is generally applied to a reverse-osmosis system, and if the traditional osmosis membrane is used in a forward-osmosis process, the water flux of osmosis is far lower than a theoretical value since the traditional osmosis composite membrane is large in thickness, the hydrophilicity of a supporting layer of a polyamide layer is poor so as to cause serious inner concentration polarization. The preparation method comprises the following steps: blending a polymer with a modifier to form film casting liquid; after scraping or leveling, performing non-solvent coagulating bath with water; by a phase-inversion method, preparing a polysulfone ultrafiltration membrane with good hydrophilicity, high porosity, uniform surface pore structure and narrow pore diameter distribution; and in a clean environment and at room temperature, airing the polysulfone membrane till the surface is dry, and growing a polyamide active layer on the surface of the polysulfone membrane by an interfacial polymerization method, thereby obtaining the forward-osmosis composite membrane with good hydrophilicity, high porosity, low thickness and high mechanical strength. The high-water-flux forward-osmosis composite membrane disclosed by the invention has the advantages that not only the osmosis flux is high, but also the reverse leakage of an extraction medium is low, and the selective permeability is good.

The invention discloses a coiled reverse osmosis membrane element, which is formed by winding at least one group of water purification membranes on a central water yielding pipe, wherein the water purification membrane group consists of a purified water guide net, a reverse osmosis membrane and a water inlet guide net which are overlapped; a water inlet flow channel is formed by folding the inner surface of the reverse osmosis membrane, and a water yielding flow channel is formed between the adjacent outer surfaces; the water inlet guide net is positioned in the water inlet flow channel; the purified water guide net is positioned in the water yielding flow channel; the water yielding flow channel only has a purified water outlet facing the central water yielding pipe, and other three sides of the water yielding flow channel are closed and sealed; the partial zones, far away from the central water yielding pipe, on the two sides, adjacent to a folded side, of the water inlet flow channel which are closed and sealed; so a small section raw water inlet is formed on the two sides close to the central water yielding pipe respectively and a thick water outlet is formed on the side of the water inlet flow channel opposite to the folded side. Through improvement, the reverse osmosis membrane element of the invention increases the water velocity on the surface of the membrane, reduces the concentration polarization on the surface of the membrane, and reduces the pollution speed of the coiled membrane element so as to prolong the service life of the membrane element.

The invention discloses a preparation method of a layer-by-layer self-assembled hollow fiber forward osmosis membrane. The preparation method comprises the steps of: preparing hollow fiber forward osmosis base film, modifying hollow fiber ultrafiltration base film, repeating layer-by-layer assembly of polycation and polyanion layers, performing interface cross-linking polymerization for preparinga selective functional layer, conducting moisturizing, and carrying out treatment and storage so as to prepare the layer-by-layer self-assembled hollow fiber forward osmosis membrane. The surface of the hollow fiber self-support base film which is prepared by using a phase conversion method is activated firstly, layer-by-layer assembly of polycation and polyanion is repeated on the surface of thefilm so as to form an functional polarization layer for an electrolyte solution, and the polyamide selective layer is prepared through interfacial chemical cross-linking polymerization. The prepared hollow fiber forward osmosis membrane has a controllable thickness and an internal polarization layer with a high charge capacity, and the internal concentration polarization phenomenon can be alleviated effectively during the forward osmosis process; therefore, the hollow fiber forward osmosis membrane can simultaneously obtain high flux and low reverse salt flux, has high filtration separation efficiency, easy cleaning and a long service life, and can be widely applied to seawater desalination and concentration and desalination of brine.

Periodically operating a forward osmosis (FO) semi-permeable membrane element in reverse osmosis (RO), to yield product extraction on a feed side of the membrane, to flush out a concentration polarization (salt concentration of the feed side and dilution of draw solution on the draw side) across the membrane. Utilizing treated waste water to generate the flushing solution of low osmotic pressure, and gauge pressurizing the flushing solution to the gauge pressure of the draw solution to keep a constant gauge pressure of the solutions. FO process is interrupted every 5-20 minutes for a 10-60 seconds long flushing RO process, thereby increasing the FO throughput five fold and recovering power from the increased throughput, i.e. from the osmotic pressure of the brine.

The invention relates to a novel battery system which can reduce leakage current of a redox flow battery and improve the charge-discharge performance of the battery. Each of a positive pole liquid storage tank and a negative pole liquid storage tank is completely isolated into an upper part and a lower part by a partition plate respectively. Firstly, positive pole electrolyte flows from a positive pole pump, flows through the battery and flows back to the upper half part of the positive pole liquid storage tank, when liquid level achieves a liquid level induction device, a valve is opened automatically, the valve is closed automatically after completing discharge of the electrolyte, the circulation is performed in such a way, and a pressure balancing pipe is shown in the figure. In a similar way, the operation way on the side of a negative pole is as that of a positive pole. By adopting the method, a main loop of the electrolyte above 90% of time is in cut-off state, and the leakage current can be further reduced (when multiple storage tanks and multiple spaces are adopted, the leakage current of the main loop can be cut off by 100%). Simultaneously, by adopting the intermittent-like charge-discharge way, the impacts of differential concentration polarization can be reduced, and the SOC (state of charge) / SOD (state of discharge) state of the redox flow battery can be improved.

The invention discloses a rapid container formation charging method for a lead-acid storage battery. The charging method is implemented through 27 charging and discharging stages, including eight times of discharging, one time of standing and one time of capacity checking and matching, wherein a maximum charging current is 0.15C<3> to 0.20C<3>, and a minimum charging current is 0.01C<3> to 0.05C<3>. The lead-acid storage battery is charged and discharged repeatedly, and a quantity of electricity charged each time is larger than a quantity of electricity discharged subsequently. Through adoption of the method, concentration polarization phenomena can be reduced greatly, and damages to crystal structures of active substances on a pole plate are reduced, thereby prolonging the service lifecycle of the lead-acid storage battery. As indicated by a detection performed according to specifications in GB / T18332.1-2009, the service lifecycle of the lead-acid storage battery adopting the method is greater than 450 times, and an initial capacity of the lead-acid storage battery is not less than 100 percent (counted by a rated capacity)

The invention relates to a high-current density metal electrolytic deposition device with bottom inlet liquid circulation and a realization method thereof. The device comprises an electrolytic tank, cathode plates and anode plates, wherein conducting rods are arranged on the cathode plates and the anode plates; the cathode plates and the anode plates are accommodated in the electrolytic tank; a circulating flow liquid inlet device is mounted at the bottom of the electrolytic tank, and comprises a circulating tank, a solution circulating channel, a circulating pump, a lower tank and an overhead tank; the lower tank and the overhead tank are connected through an extraction-reverse extraction system; the lower tank is connected with one end of the circulating tank through an overflow pipe; and the overhead tank is connected with the other end of the circulating tank through a pipe to form circulation. The device has the following benefits: the device accelerates the migration speed of metal cation through increasing the circulating flow of catholyte to eliminate the cathode concentration polarization and to realize higher cathode current efficiency and high-quality cathode products under the condition of high cathode current density, so that the purpose of prominently improving the production capacity of unit electrolysis devices is achieved through largely increasing the current density.

The invention provides a method for treating high-salt water by air stripping type membrane distillation. In the method, an air compressor is arranged in the system, a hydrothermal circulation pump and the air compressor jointly generate a gas-liquid two phase flow on a high-temperature side of a hydrophobic membrane, an electromagnetic valve is arranged on an air pipe, and pulse air intake is formed by the intermittent opening and closing of the electromagnetic valve. The method can effectively control membrane pollution and ensures the stable and high-efficiency operation of a membrane distillation device. The method has the main advantages of effectively relieving the concentration polarization of membrane distillation and preventing the formation of a gel layer due to the scraping effect of air bubbles on membrane surfaces in the gas-liquid two phase flow, and improving the turbulence scale of the membrane surfaces, increasing the membrane surface flow rate, reducing the concentration of membrane surface salt solution and increasing membrane permeation flux due to the adoption of pulse air intake. Air passing through a membrane component can be used for cooling membrane distillation penetrating fluid. The method of the invention can treat salt water with an extremely high concentration.

The invention relates to a hollow-fiber membrane module of an additional electric field, comprising a module casing (13), an anode (4), a cathode (14) and a U-shaped hollow-fiber membrane silk (12), wherein the module casing (13) is provided with a water inlet (3), an air release valve (5) and a cross flow water outlet (11) at the upper casing and the lower casing, the anode (4) is arranged at the central axis of the module casing (13), the cathode (14) is arranged outside the anode (4), the U-shaped hollow-fiber membrane silk (12) is arranged between the anode (4) and the cathode (14). In the process of membrane filtration, under the action of the electric field, charged organics or particles go through electrophoretic migration, electrocoagulation, which can reduce concentration polarization and membrane pollution caused by the charged organics or particles. The module of the invention integrates the electric field with the hollow-fiber membrane, thus giving play to the advantages of the hollow-fiber membrane, such as high filtration and separation efficiency, large membrane filtration area and small occupied space; in addition, multiple modules can be connected in parallel to obtain higher filtration speed and enhance membrane separation efficiency, as a result, the hollow-fiber membrane module enjoys extensive application prospect in the field of deep processing concerning water treatment.

A gas-separation membrane, membrane module and membrane process for controlling humidity in an environment. The membrane has a porous support zone impregnated by a selective zone, a configuration that reduces concentration polarization within the membrane itself when the membrane is housed in the module and used in the process.

This invention discloses an adaptive constant current intermittent pulse time-limit charge method, which applies an alternation method of charge / stop to charge to eliminate ohm polarization and electrochemical polarization when stopping charging, and concentration polarization will be eliminated gradually, when polarization is eliminated, the end voltage of a cell will be reduced and charged again when reducing to a stipulated value and the charge efficiency will be increased greatly, the highest charge voltage is reduced automatically when the temperature of the cell rises.

The embodiment of the invention discloses a method and device for activating a proton exchange membrane fuel cell. The method comprises the following steps of: continuously adding deionized water to a gas channel of the proton exchange membrane fuel cell; adjusting a galvanic pile clamp of the cell according to a preset rule after stopping adding deionized water and removing the deionized water; continuously pumping corresponding reaction gases to the gas channel and adjusting a load so that a current is output according to a preset step gradient until the output voltage of the cell reaches apreset voltage; fully moisturizing a membrane electrode by continuously adding deionized water to the gas channel; decreasing ohmic polarization and concentration polarization to acquire an optimal range between the ohmic polarization and the concentration polarization by adjusting the galvanic pile clamp; and outputting the current by the cell according to the preset step gradient by adjusting the load after pumping the reaction gases so that the transmission channels of water, heat, electrons, protons and gases are internally adjusted, more catalysts become effective reaction points, and the activation effect is better.

The invention belongs to the technical field of membranes, and discloses a high-performance forward permeable membrane and an electrostatic spinning preparation method thereof. The method comprises the steps that a hydrophilic nano material and a hydrophilic macromolecular polymer are mixed and dissolved, an electrostatic spinning technique is adopted for preparing a composite nanofiber membrane; then the laminated composite nanofiber membrane is adopted as a supporting layer, an interfacial polymerization technology is utilized for synthesizing a dense skin layer on the surface of the supporting layer, and the forward permeable membrane supported by the nanofiber membrane is prepared. The prepared forward permeable membrane is high in water flux and salt rejection, and internal concentration polarization can be effectively relieved through the support-shaped structure and communicated pores of the forward permeable membrane.

The invention discloses a cryo-concentration method of juice obtained by processing organisms, comprising the following steps: firstly pretreating the juice by using isoelectric precipitation, flocculation precipitation, centrifugal separation and the like to gather protein and reduce the protein content in the juice, so as to reduce the concentration polarization of membrane concentration; and then integratedly cascading membrane modules to concentrate small-molecule nutrient and flavor substances by fully utilizing the advantages of microfiltration, ultrafiltration, stepwise rejection of reverse osmosis, and desalination of electrodialysis to reduce osmotic pressure. The method is suitable for the juice obtained by processing organisms having a content of concentrated amino acid nitrogen being 5-100 mg / 100ml and has a wide application range. The method can not only concentrate and recover nutrient and flavor substances, transforms the juice into something valuable, raises the product additional values, reduces the discharge of food processing waste water, reduces environmental pollution, and can basically realize the basically complete recycling of the nutrient and flavor substances of the juice.

The invention provides a mono-trapezoid flow battery, a poly-trapezoid flow battery and an electric pile thereof. Both a cathode porous electrode and an anode porous electrode in the mono-trapezoid flow battery are trapezoidal plate electrodes and are respectively arranged inside a cathode electrolyte flow frame and an anode electrolyte flow frame. On the cathode electrolyte flow frame and the anode electrolyte flow frame, two electrolyte inlet flow paths are arranged nearby the lower bottom edges respectively of the cathode porous electrode and the anode porous electrode, and two electrolyte outlet flow paths are arranged nearby the upper bottom edges respectively of the cathode porous electrode and the anode porous electrode. The electrolyte flows into the cathode porous electrode through the lower bottom edges of the cathode porous electrode and the anode porous electrode and then flows out from the upper bottom edges of the cathode porous electrode and the anode porous electrode. The trapezoid flow battery is reduced in concentration polarization at certain degree and further is reduced in voltage loss, and meanwhile, is improved in utilization efficiency of the electrolyte and is increased in total efficiency.

The invention relates to an immersed vacuum membrane distillation plant and a sewage treatment technology using the same. The immersed vacuum membrane distillation plant comprises a raw water storage tank, a gas dissolving pump, a raw water heating water tank, a membrane distillation hydrophobic membrane module, a condenser, a vacuum buffer tank, a vacuum pump, a water producing tank, a valve, a measuring instrument, and an automatic controller. The sewage treatment technology is characterized in that: raw water is subject to pH regulation, microfiltration and other pretreatment, then the pretreated raw water enters into the raw water storage tank, the sewage in the raw water storage tank is subject to gas-water mixing through the gas dissolving pump, and then the gas-water mixture enters into the raw water storage tank for heating to a specific temperature, membrane distillation is carried out at the specific temperature, the produced water after membrane distillation is directly reused, and a little thick water is treated concentrately. According to the invention, the use of the plant in sewage treatment reduces the effect of concentration polarization and temperature difference polarization in the sewage, reduces membrane pollution, increases the membrane distillation flux, prolongs the operation period of the membrane module, reduces the heat loss of the pipeline, and increases the heat utilization rate.

The invention relates to a preparation method for a proton exchange membrane fuel cell gas diffusion layer under high current density. The preparation method comprises the following steps: firstly, carrying out hydrophobic and drying treatment on a substrate layer, then preparing slurry by utilizing carbon powder, a solvent, a hydrophobic agent and a pore-forming agent, then uniformly attaching the slurry to the substrate layer by adopting a blade coating method and reaching a certain loading capacity, and finally drying and sintering to obtain the gas diffusion layer. A plurality of cracks are formed on the surface of the microporous layer of the gas diffusion layer after the gas diffusion layer is treated, permeation of gas and water can be effectively ensured, the water management capability of the gas diffusion layer is improved, the concentration polarization of the membrane electrode under high current density is reduced, and the performance of the proton exchange membrane fuel cell is improved. The method has the advantages of low cost, simple preparation process and the like, and is particularly suitable for commercial large-scale use.

The invention relates to an electroforming combined processing device and an electroforming groove used in the device. The device comprises an electroforming mandrel supporting device and the electroforming groove, wherein, an energy transducer device is arranged on the electroforming mandrel supporting device or / and inside the electroforming groove, and an energy transducer of the energy transducer device is in electric connection with an ultrasonic generator. A multi-frequency ultrasound irradiating system consisting of cathode ultrasound and groove type ultrasound is acted on the electroforming process in a way of alternating coupling, and more cavitation cases are generated by the ultrasound vibration of the cathode mandrel and the ultrasound vibration of an electrolysis bath to obtain intensified ultrasound cavitation effect, thereby intensifying the conflict and perturbation on the electroforming mandrel surface, effectively removing bubbles on the electrode surface, ensuring that the current passes through the electrode smoothly, increasing the moving speed of positive ions to the cathode, reducing the concentration polarization in order to increase the electroforming speed, thinning crystal grains of the metal electrocrystallization, and obtaining an electroforming product with even surface and even and compact tissue.

The invention relates to a method for preparing a polyvinylidene fluoride composite cellulose acetate forward osmosis membrane. The conventional product has a serious inside concentration polarization phenomenon and low actual flux. The method comprises the following steps of: preparing a polyvinylidene fluoride cast membrane solution from polyvinylidene fluoride and additive; preparing a cellulose acetate cast membrane solution from cellulose acetate, cellulose triacetate and molecular sieve; and uniformly coating the polyvinylidene fluoride cast membrane solution on a non-woven fabric to obtain a hydrophilic polyvinylidene fluoride micro-filtration base membrane, drying or naturally drying in air to form a dry hydrophilic polyvinylidene fluoride membrane, uniformly coating the cellulose acetate cast membrane solution on the dry hydrophilic polyvinylidene fluoride membrane, and thus obtaining the composite forward osmosis membrane. The forward osmosis membrane prepared by the method has high mechanical strength and solvent tolerance, high water flux and high salt intercepting rate, and can be applied in the fields of desalting of seawater and brine, softening of hard water, first-aid water bags and the like.

The present invention relates to an apparatus for monitoring the progress of membrane fouling that occurs on pores as well as on the surface of a membrane by means of variations of zeta potential (zeta) of a hollow-fiber membrane according to time passage of filtration of a suspension, wherein colloid particles, biopolymers and other inorganic particles are dispersed, and the method thereof. Moreover, the present invention also relates to a method to identify the effect of concentration polarization layer and cake layer which can vary according to the axial position of a hollow-fiber and the developing progress of a membrane fouling by measuring the position-dependent zeta potential of the hollow-fiber membrane.

The invention discloses a metallic electrolytic cell which comprises a cell body, anode plates, cathode plates and arc-shaped drainage bulges, wherein the arc-shaped drainage bulges are mounted at the two opposite ends of the cell body; the anode plates and the cathode plates are alternatively arranged in the cell body, and liquid inlets and overflow openings are formed in the cell body; the liquid inlets in the two sides of each cathode plate are positioned in the same end of the cathode plate, and the liquid inlets in the two sides of each anode plate are respectively positioned in the two ends of the anode plate; the two ends of each cathode plate are respectively butted with the convex ends of the arc-shaped drainage bulges, and a liquid drainage cavity is formed between the cathode plates and the arc-shaped drainage bulges. Two adjacent cathode plates and one anode plate between the cathode plates form a similar closed space, electrolyte is fast ejected to enter the space through the liquid inlets in one end of one cathode plate and the other end of the adjacent cathode plate, and then the electrolyte flows clockwise and anticlockwise. The kinetic energy of electrolyte is utilized, the concentration difference of metal ions between the two pole plates is greatly reduced, and the concentration polarization is effectively reduced. The invention further discloses a metal electrolysis process.

The invention discloses a reciprocating rotation type feed liquid and film separation method and a reciprocating rotation type feed liquid and film separation device. The device comprises a feed liquid barrel, a hollow revolving shaft, a rotating disc, a film component and a driving mechanism, wherein the feed liquid barrel is provided with a feed liquid inlet and a discharge hole; the hollow revolving shaft is rotationally arranged in the feed liquid barrel and provided with a liquid outlet; the rotating disc is fixed on the hollow revolving shaft; the film component is fixed on the rotating disc and rotates synchronously along with the rotating disc; the driving mechanism drives the film component to rotate positively and negatively in a reciprocating way; and the positive rotation speed and time of the film component are the same as negative rotation speed and time. The film component rotates positively and negatively in a reciprocating way, so that the speed gradient of a feed liquid flow field on the surface of the film is increased, the shearing stress of liquid is effectively enhanced, film pollution and concentration polarization can be constrained remarkably, flux depression of the film is delayed remarkably, better feed liquid separation effect and higher efficiency are achieved, film cleaning frequency can be reduced and running cost is lowered. The method and the device can be applied in various fields such as bioengineering, medicaments, foods, beverages and waste water treatment and the like.

The invention relates to an internal formation process of a super battery. The internal formation process comprises the following major steps: pouring a certain volume of acid solution with certain concentration into a super battery by use of a vacuum method first before formation, standing for 2-4 hours, and carrying out internal formation of the battery in a manner of four charge times and three discharge times with short time and multiple periods by adopting fixed current. Due to the multi-cycle charge-discharge manner, the porosity of a polar plate and the utilization rate of active substances are greatly increased, the influence on concentration polarization and electrochemical polarization is effectively alleviated, the capacitive character of a carbon material in the polar plate can be effectively activated, and therefore, the large current charge-discharge and cycle life properties of the super battery are improved.

The invention provides a thin layer composite positive osmosis membrane and a preparation method of the thin layer composite positive osmosis membrane, aiming at effectively reducing concentration polarization in positive osmosis and greatly improving the water flux. The invention provides a thin layer composite positive osmosis membrane containing an ultrathin support layer, and a preparation method of the thin layer composite positive osmosis membrane, so that the defects of the prior art are made up. The ultrathin support layer of the thin layer composite positive osmosis membrane is a self-support carbon nano tube support layer or a hydrophilic modification carbon nano tube support layer; a skin layer of the thin layer composite positive osmosis membrane is a polyamide layer compounded on the surface of the self-support carbon nano tube layer. Due to the good support layer structure of the self-support carbon nano tube layer, a brand new thin layer composite positive osmosis membrane concept is provided, so that a new way of a high-performance positive osmosis membrane is opened up at home and abroad. Furthermore, the operation of interfacial polymerization is completed on the surface of the self-support carbon nano tube layer, the positive osmosis membrane with remarkably improved performances can be obtained, and a new thought is provided for the preparation of other novel materials.

The invention discloses a coiling type reverse osmosis membrane element with even water distribution. In the coiling type reverse osmosis membrane element, a central pipe is positioned in a inflow runner, and a plurality of water inlet holes opposite to the inflow runner are distributed on a pipe body; and a reverse osmosis membrane is provided with a concentrated water outlet communicated with the inflow runner at the circumferential surface of the coiling type reverse osmosis membrane element and provided with a pure water outlet communicated with a water producing runner on at least one end surface of the coiling type reverse osmosis membrane element by seal processing. The coiling type reverse osmosis membrane element with even water distribution has the advantages of improvement of the water flow rate on the membrane surface, reduction of the concentration polarization on the membrane surface and reduction of the pollution speed of a coiling type membrane element for prolonging the service life of the membrane element, simple structure and high production operability.

The invention relates to an impulse type electroosmosis dewatering processing method for soft soil and silt. The method adopts the impulse type electroosmosis dewatering and uses supporting methods of vacuum precompaction, dead-load, power compaction, etc., to build or keep the capillary structure of the soft oil and slit; then under the effect of pulse current, concentration polarization is reduced so as to reduce electricity consumption; the ionization ratio of water is increased, which leads the ionized water in the capillary structure of the soft oil and slit to move towards cathode and form osmotic flow that moves towards the cathode, and the osmotic flow gathers to the cathode and is discharged outside by a vacuum pumping system so as to achieve the purpose of dewatering the soft soil and the silt.

The invention provides a lithium-iron-phosphate-battery fractional-order equivalent circuit model establishing method based on frequency demultiplication representation. In view of the irregular performance and the asymmetry performance of a lithium battery material, the circuit characteristics of a lithium battery are represented with a fractional-order differential method defined based on Caputo; due to the memory characteristic of fractional-order differential, an equivalent circuit model obtains the higher freedom degree and the higher stability; when the fractional-order circuit model is solved, the impedance frequency difference between activation polarization and concentration polarization is considered, the medium frequency band and the low frequency band are respectively subjected to discrete approximating through an Oustaloup approximation approaching filter, and therefore the model obtains the higher approximation accuracy and dynamic performance. Finally, the parameters of the frequency-demultiplication fractional-order equivalent circuit model are identified through a pulse charging-discharging experiment, the stability, the dynamic performance and the accuracy of the lithium-battery equivalent circuit model are improved, and practical engineering significance is achieved.

The invention belongs to the technical field of membrane separation, and particularly relates to a forward osmosis composite membrane based on a two-dimensional nano material and a macroporous substrate and a preparation method and application of the forward osmosis composite membrane. According to the composite membrane, a two-dimensional nano material is deposited on the surface of a macroporoussubstrate to serve as a middle layer, a polyamide separation layer is formed on the surface of the middle layer, and the composite membrane is obtained. The two-dimensional nano material middle layerin the composite membrane prevents polyamide from permeating into the macroporous substrate to damage the original macroporous and mutually communicated pore structure, reduces the mass transfer resistance, and effectively relieves the internal concentration polarization phenomenon in the forward osmosis process, thereby greatly enhancing the separation performance of the polyamide composite membrane and prolonging the service life of the composite membrane. The forward osmosis composite membrane can be widely applied to seawater desalination, juice concentration and other fields.

The invention provides a formation and matching method for a lithium ion battery. For forming a stable and uniform SEI film and screening out batteries with similar performances, a low-current pulse and high-current charging-discharging circulation mode is adopted; concentration polarization on the surface of an electrode is eliminated by low-current pulse charging, so as to form the stable and uniform SEI film; the active material of the electrode is activated by the high-current charging-discharging circulation so as to balance the rate capacity of the battery; by increasing current, the heating amount among different batteries can be increased; and therefore, the batteries with similar capacity and same heat dissipation can be matched into a battery pack more accurately according to the capacity and the heating amount of the batteries, thereby improving the uniformity of the battery pack.