28 results about "Membrane porosity" patented technology

The invention discloses a method for detecting porosity of a solid electrolyte composite diaphragm, and relates to the technical field of lithium battery diaphragm detection.The method comprises the following steps that the solid electrolyte composite diaphragm is pretreated in advance, a pretreated diaphragm sample is obtained, and pretreatment at least comprises sample cutting and vacuum freeze drying; establishing a measurement system, performing dynamic adsorption measurement according to the measurement system, obtaining the adsorption quantity and the adsorption rate, obtaining the effective diffusion coefficient De of the diaphragm, and calculating the porosity epsilon. Dynamic adsorption measurement is adopted, the pressure change in the adsorption process is monitored in real time, and rich adsorption capacity and adsorption rate data are obtained. In combination with a linear driving force LDF model, adsorption kinetics factors are fully considered, the effective diffusion coefficient of the diaphragm is obtained by fitting model parameters, and then the porosity is calculated. Compared with a traditional method, the method has the advantages that the influence of a complex pore structure in the diaphragm on the adsorption process can be reflected more accurately, and the accuracy of porosity calculation is improved.

The invention discloses a high-power battery pole group which is characterized in that a middle-section coating of a positive plate is made of a lithium-intercalated and de-intercalated high-rate discharge active material, an upper-section coating and a lower-section coating are made of materials with insulation and liquid absorption capabilities, and the liquid absorption capability of the lower-section coating is greater than that of the upper-section coating; the negative plate upper-section coating is an active material for bearing rapid embedding of lithium ions, and the negative plate lower-section coating is a porous liquid absorption layer formed by an active material which contains a large-particle-size main body material and has rapid liquid absorption capability; the diaphragm upper-section coating and the diaphragm lower-section coating are made of a ceramic material which has liquid absorbing and retaining capabilities and can expand after absorbing liquid to fill a gap between a positive electrode and a negative electrode at the top end, the diaphragm middle-section coating does not have the liquid absorbing capability, and the porosity of a base membrane on which the diaphragm lower-section coating is positioned is greater than that of the base membrane of the middle-section coating and the upper-section coating. According to the invention, the problems of structural lithium precipitation and imbibition lithium precipitation are solved, and the service life of the high-power battery cell is guaranteed in all directions.

The present invention provides a battery, comprising a positive electrode plate, a negative electrode plate, an electrolyte and a separator; the positive electrode plate comprises a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector; the negative electrode plate comprises a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector; the battery satisfies 0.45 ≤ 1000×(25p1 2 + 16p2 2 )×p3 / (c×t) ≤ 0.6. Compared with the prior art, by reasonably matching the positive electrode coating surface density, the coating porosities of the positive and negative electrodes, the separator porosity and the separator thickness, the battery prepared by the present invention has excellent energy density and can provide high-power output performance, meeting the usage requirements of EVTOL.

The present application relates to the technical field of powder membrane filter element, and particularly relates to a numerical modeling method and system of sintered metal porous membrane filter material, which comprises obtaining powder membrane porosity and particle size distribution; initializing geometric space; generating particle sphere center coordinates and particle size; judging whether newly generated particle spheres overlap with original particle spheres; calculating theoretical total volume; judging the adjacent overlapping relationship between particle spheres, and using an array to record all original particle spheres overlapping with the generated particle spheres; calculating the overlapping volume between the newly generated particle spheres and all original particle spheres; calculating the actual total volume of the total particle spheres and the total porosity; and continuously iterating until the total particle spheres are less than the porosity of the powder membrane, and then stopping iteration. The present application provides a numerical model construction method of real physical microstructure characteristics of the powder membrane, generates an accurate model conforming to the entity structure characteristics of the porous membrane filter material, and is used for simulating the filtering characteristics of the porous material.

The application relates to a preparation method of a high-porosity high-flux asymmetric membrane, and belongs to the field of membrane separation technology. The preparation method of the high-porosity high-flux asymmetric membrane comprises the following steps: uniformly dissolving a polymer and a hydrophilic additive in an organic solvent to prepare a homogeneous casting solution; preparing a nascent membrane from the casting solution; then, performing atomization pretreatment on the nascent membrane; rapidly cooling the nascent membrane after the pretreatment; then, immersing the nascent membrane in a gel bath to form an asymmetric membrane; and performing multiple flushing and soaking on the asymmetric membrane in normal-temperature deionized water to obtain the high-porosity high-flux asymmetric membrane. The asymmetric membrane adopts a non-solvent atomization technology combined with cooling-induced crystallization, the non-solvent atomization is introduced into the surface of the nascent membrane, the solution is rapidly saturated by accurate temperature control, the crystal formation is triggered, the macroporous pores are formed, and the membrane porosity and flux are improved. The obtained asymmetric membrane has a macroporous network on the surface layer and a finger-shaped pore on the support layer, the porosity is 75% to 85%, the pure water flux is greatly improved, and the high-efficiency separation requirement is met.

The utility model relates to a novel aerator which comprises a ventilation piece, a mounting piece and a polyethylene microporous aeration membrane, the aeration piece is connected with the mounting piece through the ventilation piece, the polyethylene microporous aeration membrane is arranged on the mounting piece, an aeration cavity is formed between the polyethylene microporous aeration membrane and the mounting piece at an interval, and a ventilation channel on the ventilation piece is communicated with the aeration cavity through a ventilation hole. Air can be conveyed into the aeration cavity through the ventilation piece, the polyethylene microporous aeration membrane has the advantages of being high in membrane porosity, super large in specific surface area, low in aeration resistance, close to zero in aperture deformation, resistant to acid and alkali and resistant to high salt, after airflow passes through the polyethylene microporous aeration membrane, micro-nano bubble aeration can be achieved, the oxygen transmission efficiency is improved, and the aeration effect is improved. The service life is long.

The invention belongs to the technical field of biomass materials and green chemical engineering, and discloses a green preparation method and system of a high-porosity cellulose porous membrane based on solvent replacement. The invention aims to solve the problems that the pore structure is easy to dry and collapse, the solvent cost is high and the environment is not protected when the cellulose porous membrane is prepared in the prior art. The core of the method is that cellulose is dissolved in a lithium bromide aqueous solution, and a cellulose hydrogel network is formed through cooling solidification and washing regeneration; then, completely replacing the hydrogel by using a low-surface-tension alcohol or ketone solvent (such as tertiary butanol) so as to eliminate destructive capillary force in the drying process and maintain a porous structure; and finally, drying at normal pressure to obtain the high-porosity cellulose membrane. The core of the system is that a three-loop recycling system of lithium bromide and alcohol or ketone solvents is integrally designed, and near-zero emission and cyclic utilization of the solvents are achieved. The prepared cellulose porous membrane is high in porosity (50-80%) and controllable in structure, and the whole process is green, economical and suitable for large-scale production.

The invention discloses a mesoporous alumina composite diaphragm, a preparation method and application. The composite diaphragm comprises a polar polymer layer and a porous alumina layer which are laminated. The polar polymer layer can reduce the charge transfer impedance of the lithium battery and improve the cycle capacity of the lithium battery; meanwhile, the polar polymer layer is rich in polar groups and can absorb a large amount of electrolyte; the porous aluminum oxide layer can reduce the stacking density of the diaphragm coating layer, so that the diaphragm is light; meanwhile, the problem that the porosity of the base membrane and the ionic conductivity are reduced can be solved; in addition, the porous aluminum oxide layer has a flat surface and can induce lithium nucleation homogenization, so that the growth of lithium dendrites is inhibited.

The invention provides a preparation method of a PVDF (Polyvinylidene Fluoride) modified porous membrane, which belongs to the technical field of membrane separation, and provides a recrystallization post-treatment method for the first time: firstly, oxidizing a PVDF membrane to form a large number of disordered molecular chains, subsequently enabling the molecular chains to tend to form a beta crystal phase through an inducer, and finally, annealing the separation membrane at low temperature, and further amplifying the induction effect under thermal activation. Molecular chains are directionally rearranged, so that conversion from an oxidation region to a beta crystal phase crystalline region is realized, and the ratio of the beta crystal phase in the PVDF film is greatly increased. The beta crystalline phase molecular chain is highly oriented and has strong rigidity, and fiber fusion in the PVDF membrane is effectively inhibited, so that the fiber diameter is reduced, the fiber spacing is enlarged, the membrane porosity is improved, the duct tortuosity is reduced, and the membrane flux is greatly improved.

This utility model discloses a lithium battery sheet metal box, including a top cover with a venting structure. The venting structure connects the interior and exterior of the lithium battery sheet metal box to allow gas generated inside the battery to escape. The venting structure includes a venting component and a waterproof and breathable membrane. The venting component includes a large-hole section and a small-hole section, which are connected by a stepped surface. The large-hole section is detachably connected to a fixing component. The waterproof and breathable membrane is clamped and fixed between the stepped surface and the fixing component, thus preventing the membrane from easily falling off. The fixing component has a through hole connecting the waterproof and breathable membrane to the interior of the sheet metal box. Furthermore, during the airtightness test of the lithium battery, the yield rate of the lithium battery sheet metal box can be ensured by replacing the waterproof and breathable membrane between the venting component and the fixing component. Alternatively, the membrane can be replaced when the membrane porosity increases and / or the waterproof and breathable membrane is damaged, causing a decrease in waterproof performance, to ensure the safety of the lithium battery sheet metal box during use.

This invention provides a novel method for preparing and applying a composite nanomaterial-modified organic membrane, belonging to the technical field of filtration membranes for wastewater treatment. The method involves adding a modified carbon nitride nanocomposite material (made from graphitic carbon nitride nanomaterials) and a pore-forming agent to an organic solvent, followed by ultrasonic treatment to obtain a mixed solution. Then, a polymeric membrane material is added to the mixed solution, and the mixture is stirred at a constant temperature and allowed to stand to remove bubbles, forming a casting solution. The prepared casting solution is then used to prepare the composite nanomaterial-modified organic membrane. This invention improves the hydrophilicity and dispersibility of C3N4 nanomaterials in the casting solution, accelerates the phase transformation rate of the composite membrane, increases the membrane porosity, increases the membrane's negative charge, and improves the membrane's antifouling performance. It also solves the problems of low flux and severe membrane fouling that exist in the operation of composite organic membranes.

The present invention discloses a method for preparing para-aramid nanofiber membranes by airflow-assisted coaxial spinning, comprising: ultrasonically drying short PPTA fibers in anhydrous ethanol, and dissolving them in a deprotonated system to obtain an ANF suspension; dissolving PEO powder in N,N-dimethylformamide to obtain a PEO solution, respectively injecting the solution into the corresponding pipes of the coaxial spinning needles, performing airflow-assisted coaxial spinning, depositing the fibers on a water bath receiving net to form a fiber membrane, and then washing and drying the resulting pure ANF. The ANFs obtained by airflow-assisted coaxial spinning retain the excellent properties of macroscopic PPTA fibers while exhibiting the unique characteristics of ANFs, such as small fiber diameter and high membrane porosity. They can be applied to lithium-ion battery separators, thermal insulation, filtration, and other fields.

The invention relates to the technical field of lithium ion batteries, in particular to a composite diaphragm for in-situ gelation of an electrolyte, a battery cell, application and a method. The composite diaphragm comprises a base membrane with the porosity of 40-50%, a ceramic coating arranged on at least one side of the base membrane, and an oxide solid electrolyte coating arranged on the outer side of the ceramic coating and / or the other side of the base membrane, wherein the thickness ratio of the ceramic coating to the oxide solid electrolyte coating is (1-5): 1. The permeability and structural stability of a gel monomer in the in-situ curing process are ensured by controlling the porosity of the base membrane, the ceramic layer provides thermal support and mechanical stability, and the oxide solid electrolyte coating and a gel system form a chemically compatible transition interface. Through collaborative design of interlayer thickness ratios, dense and continuous generation of a gel network is realized, and the bonding stability of a diaphragm and a gel interface is improved, so that the cycle consistency and high-temperature safety performance of a battery cell are improved.

The application discloses a cellulose diaphragm, a preparation method thereof and a lithium battery, and relates to the technical field of battery diaphragms. In the process of forming a film by using a cellulose dispersion liquid, calcium carbonate is introduced, and the porosity and pore size are adjusted by a calcium carbonate pore forming method; acid liquid containing chitosan is used for reaction, chitosan is introduced while the calcium carbonate is removed, the strength of the diaphragm can be increased, the migration of anions can be inhibited, and the electrochemical performance of the diaphragm is improved. The prepared lithium ion battery diaphragm has a porosity of 60-70%, a tensile strength greater than 45 MPa, an ion conductivity greater than 1.7 mS cm ‑1 , and a lithium ion migration number greater than 0.5.

The invention discloses a high-flux PVDF (polyvinylidene fluoride) hollow fiber ultrafiltration membrane based on PVP (polyvinyl pyrrolidone) regulation and control and a preparation method of the high-flux PVDF hollow fiber ultrafiltration membrane. By optimizing a PVDF / PVP / PEG ternary membrane casting solution system and combining a glycerol-assisted coagulating bath and a gradient ethanol replacement process, a PVDF / PVP composite layer with gradient pore size distribution (the gradient pore size distribution from the surface layer to the inner layer is from 0.02 mu m to 0.05 mu m) is formed on the surface of the PET braided tube, and the performance breakthrough that the porosity is greater than or equal to 80% and the pure water flux is greater than or equal to 1500L / (m < 2 >. H) (0.1 MPa, 25 DEG C) is realized. Through the synergistic effect of a hydroxyl (. OH) hydrogen bond network of PVP and PVDF, the problems that a traditional PEI modified membrane is low in porosity (less than or equal to 75%) and fast in flux attenuation (gt; and the method is suitable for seawater desalination pretreatment and high-turbidity wastewater treatment.

The invention discloses a black titanium system coloring long-acting stability process based on flow and temperature control. The black titanium system coloring long-acting stability process comprises the steps that 1, the surface of a titanium alloy is pretreated; step 2, preparing a black anodic oxide film; step 3, carrying out post-treatment; and 4, detecting the performance of the film layer, returning to the step 1 if the requirements are not met, and finishing production if the requirements are met. The flow of the electrolyte is controlled through the porous titanium basket, the temperature of the bath solution is stabilized through the staged temperature control strategy and the PID algorithm, the porosity and internal stress of the oxidation film are effectively reduced by combining the stepped boosting and pulse current technology, and the performance of the film layer is ensured through a real-time monitoring and self-adaptive adjusting system; the method has the advantages that the film uniformity, the process stability and the long-acting corrosion resistance are remarkably improved.

The invention relates to a preparation method of a high-porosity and high-flux asymmetric membrane, and belongs to the technical field of membrane separation. A preparation method of a high-porosity and high-flux asymmetric membrane comprises the following steps: uniformly dissolving a polymer and a hydrophilic additive in an organic solvent to prepare a homogeneous membrane casting solution; preparing a primary membrane from the membrane casting solution, then carrying out atomization pretreatment on the primary membrane, rapidly cooling after treatment, then immersing the primary membrane in a gel bath to form an asymmetric membrane, and washing and soaking the asymmetric membrane in normal-temperature deionized water for multiple times to obtain the high-porosity and high-flux asymmetric membrane. According to the asymmetric membrane, a non-solvent atomization technology is combined with cooling induced crystallization, non-solvent atomization is introduced into the surface of a primary membrane, the temperature is accurately controlled, so that a solution is rapidly saturated, crystal formation is triggered, large-aperture pores are formed, and the porosity and flux of the membrane are improved. The surface layer of the obtained asymmetric membrane is provided with a large-aperture network, the supporting layer is finger-shaped holes, the porosity is 75%-85%, the pure water flux is greatly improved, and the efficient separation requirement is met.

The invention relates to a polished wear-resistant granite ceramic tile and a preparation method thereof, and a high-simulation multilayer granite ceramic tile and a preparation method thereof. The polished wear-resistant granite ceramic tile comprises a green body layer, a colored glaze spot-spraying glaze layer, a transparent dry particle layer and a curing agent layer which are sequentially stacked from bottom to top, the colored glaze spraying spot glaze layer is formed by a multi-station dynamic glaze spraying system, the diameter range of glaze spots is 0.5-8 mm, the fluctuation height of the glaze layer is 0.3-0.6 mm, and the colored glaze spraying spot glaze layer has granite-imitated three-dimensional textures; the transparent dry particle layer is formed by transparent dry particles of 80-250 meshes through a slicking process, the thickness of the compaction layer is 0.8-1.2 mm, and the surface flatness is smaller than or equal to 0.05 mm; the filling module is used for filling and striking off peaks and valleys of the colored glaze spot glaze layer; the curing agent layer is formed by spraying a curing agent and permeates into gaps of dry particles to form a semi-cured film, the porosity is smaller than or equal to 1%, and the residual carbon content after sintering is smaller than or equal to 0.05%; the surface glossiness of the ceramic tile is 20 degrees, 45 degrees or larger than or equal to 95 degrees, the wear-resistant grade is larger than or equal to 4 grades, the anti-fouling grade is larger than or equal to 5 grades, and the color difference delta E is smaller than or equal to 1.5.

The invention relates to the technical field of reverse osmosis membrane modification, and particularly discloses a method for modifying a high-pressure industrial reverse osmosis membrane into a household low-pressure reverse osmosis membrane. The separation layer structure of the original industrial reverse osmosis membrane is precisely regulated and controlled under the mild room temperature condition, and dual optimization of the porosity and hydrophilicity of the membrane is realized. The flux of the modified membrane is increased to 45.12 LMH or above from 15.74 LMH of an original industrial membrane under the 65psi household low-pressure working condition, the NaCl retention rate is stably maintained to be 96.5% or above, meanwhile, the membrane has the advantages that the process is simple, raw materials are easy to obtain, the modification cost is low, and the membrane is high in compatibility with existing household reverse osmosis equipment, conversion from the industrial membrane to the household membrane is efficiently achieved, and the membrane is suitable for large-scale popularization and application. The industrial problems of insufficient flux and high preparation cost of the household reverse osmosis membrane are solved, secondary utilization of industrial membrane resources is realized, and the method has large-scale production and popularization values.

This invention discloses a method for preparing a bio-based aramid-coated lithium battery separator for ternary lithium batteries, belonging to the field of battery separator processing technology. This invention addresses the technical problem in existing technologies where aramid itself has low conductivity and porosity, and coating an aramid solution onto a base membrane reduces the porosity and electrical performance of the base membrane. The method for preparing a bio-based aramid-coated lithium battery separator for ternary lithium batteries includes the following steps: washing the surface of seaweed with clean water, draining it, and cutting it into small segments to obtain seaweed segments; subjecting the seaweed segments to heat treatment and modification treatment sequentially to obtain modified biocarbon; adding 4,4'-diacyl chloride diphenyl ether, 2,5-bis(allyloxy)terephthaloyl chloride, and N-methylpyrrolidone to a three-necked flask and stirring, while lowering the temperature of the three-necked flask to -20±2℃. This invention, by coating the exterior of the PE separator, not only effectively improves the porosity and mechanical properties of the separator but also enhances its electrical performance.

The invention discloses a visual coating isolating membrane porosity testing method and system, and relates to the technical field of porosity testing. The method comprises the steps that a flat plate is horizontally placed on a rotating platform, a circular contour line is drawn on the flat plate, a coating isolating membrane is placed on the flat plate, and the coating isolating membrane is located in the circular contour line; preparing an indicator, in the rotating process of the flat plate, dropwise adding the indicator on the coating isolating membrane according to a set rate until the indicator reaches the circular contour line, detecting the color of the position where the indicator reaches the circular contour line in real time by using a visual detection network, and determining the stopping time of dropwise adding the indicator; and calculating the porosity of the coating isolating membrane according to the consumed mass of the indicator. According to the method disclosed by the invention, a visual porosity testing experiment is realized by a method of dropwise adding an indicator, and a result point is accurately identified by combining a computer vision technology, so that a relatively large random error is prevented.

To provide a lamination separator for a non-aqueous electrolyte secondary battery capable of improving ion permeability after pressurization.SOLUTION: In a lamination separator for a non-aqueous electrolyte secondary battery, a porous layer is laminated on one face or both faces of a polyolefin porous film. The lamination separator satisfies the following conditions 1 and 3 or conditions 2 and 3. Condition 1: The porous layer contains fillers of which the average particle diameter is 1 μm or more. Condition 2: An uneven space capacity of a surface of the porous layer is 0.4 mL / m2 or more. Condition 3: It leads (porosity of porous layer-porosity of polyolefin porous film)÷porosity of lamination separator for non-aqueous electrolyte secondary battery≤0.6.SELECTED DRAWING: Figure 1

This invention belongs to the field of membrane preparation technology, specifically relating to an ultrafiltration membrane, its preparation method, and its applications. The method first prepares an organic / inorganic hybrid membrane containing inorganic nanoparticles. Then, the hybrid membrane is immersed in a dilute acid aqueous solution of chitosan, allowing the dilute acid to etch and remove the inorganic nanoparticles, thereby increasing the membrane porosity. Simultaneously, chitosan is deposited on the membrane surface to further improve the membrane's hydrophilicity and permeability, and to reduce the average pore size of the membrane surface. The ultrafiltration membrane prepared in this way has the characteristics of small pore size and high porosity, exhibiting both high permeability and selectivity, and shows broad application prospects in water treatment, biomedicine, and other fields.

The invention relates to the technical field of ammonia nitrogen wastewater treatment, in particular to a hydrophobic blending modified PVDF composite membrane and a preparation method thereof. According to the specific technical scheme, the preparation method comprises the following steps: (1) dissolving stearic acid in absolute ethyl alcohol, adding nano copper laurate powder, and stirring until the absolute ethyl alcohol is completely evaporated; (2) adding LiCl, PEG 20000 and a PVDF solution into the mixture obtained in the step (1), stirring at a constant temperature, and standing for defoaming to obtain a homogeneous membrane casting solution; and (3) uniformly blade-coating a glass substrate with the membrane casting solution, controlling the membrane thickness to be 150-250 [mu] m, pre-evaporating in air, immersing in a deionized water coagulating bath for phase inversion to form a hydrophobic microporous membrane, and drying to obtain the hydrophobic blending modified PVDF composite membrane. According to the invention, the problems of high surface energy, poor dispersibility, easy agglomeration and easy shedding of a nanometer material in blending modification of a traditional PVDF membrane are solved; the problems that a traditional pore-forming agent is limited in regulation and control capacity, low in membrane porosity, uneven in pore size distribution, low in mechanical strength and the like are solved.

The invention discloses a nanometer material loaded aramid fiber coating battery diaphragm and a preparation method thereof, and belongs to the technical field of battery diaphragms. The aramid fiber coating battery diaphragm loaded with the nano material comprises a base membrane and an aramid fiber coating, wherein the aramid fiber coating comprises phosphorylated water-soluble aramid fiber / MOF; the MOF is one of ZIF-8, ZIF-67, UiO-66, UiO-67, MIL-101 (Cr), MIL-53 (Al) and PCN-223, and the MOF is one of ZIF-8, ZIF-67, UiO-66, UiO-67, MIL-101 (Cr), MIL-53 (Al) and PCN-223. According to the invention, phosphorylation modification and MOF modification are carried out, so that the composite material has high porosity and excellent thermal stability and flame retardance. Wherein phosphorylation modification enables the porosity of the aramid fiber coating battery diaphragm to be increased, the polarity and the affinity of electrolyte to be enhanced, the ionic conductivity to be improved, the dispersity of MOF to be increased, and the performance of the diaphragm to be further improved.

This invention provides an MXene / polyamide dual-selective layer ceramic-based composite nanofiltration membrane, its preparation method, and its application, relating to the field of composite nanofiltration membrane technology. The composite nanofiltration membrane of this invention comprises, from the inside out, an α-Al₂O₃ ceramic support, an MXene selective layer, and an ultrathin gradient PA functional layer; the α-Al₂O₃ ceramic support is a single-channel tubular α-Al₂O₃ membrane with an average pore size of 400-700 nm and a porosity of 40%-55%; the MXene selective layer is composed of Ti₃C₂T₂... x The MXene nanosheets are stacked in an ordered manner, with a thickness of 100-400 nm and interlayer channels with a pore size of 1-5 nm. The ultrathin gradient PA functional layer has a thickness of 50-200 nm and exhibits a gradient cross-linking structure, with a high degree of cross-linking and a pore size of 0.3-0.8 nm on the side closer to the MXene selective layer, and a low degree of cross-linking and a pore size of 0.8-1.2 nm on the membrane surface side. This invention fundamentally solves the problems of poor stability and difficulty in balancing flux, selectivity, and stability of MXene membranes by constructing a sandwich composite structure of "ceramic support-MXene sieve layer-ultrathin gradient PA functional layer," thereby achieving efficient separation and resource utilization of dyes and salts.

The invention discloses a cellulose diaphragm, a preparation method thereof and a lithium battery, and relates to the technical field of battery diaphragms. Calcium carbonate is introduced in the process of forming a film by utilizing cellulose dispersion liquid, and the porosity and the pore size are adjusted by a calcium carbonate pore-forming method; the acid liquor containing chitosan is used for reaction, chitosan is introduced while calcium carbonate is removed, the strength of the diaphragm can be improved, anion migration can be inhibited, and the electrochemical performance of the diaphragm is improved. The porosity of the prepared lithium ion battery diaphragm is 60-70%, the tensile strength is greater than 45 MPa, the ionic conductivity is greater than 1.7 mS cm <-1 >, and the lithium ion transference number is greater than 0.5.

The utility model relates to a lithium battery diaphragm porosity testing device which comprises a frame body, a testing assembly is arranged on the frame body and comprises a first pressing block, a second pressing block, a liquid storage pipe and a liquid storage tank, a first air hole is formed in the first pressing block, a second air hole is formed in the second pressing block, and a groove used for containing a diaphragm is formed in the second pressing block; a sealing ring is arranged on the surface, facing the second pressing block, of the first pressing block, and a sealing groove matched with the sealing ring is formed in the second pressing block. The method has the effect of improving the accuracy of porosity measurement.