280 results about "Lithium intercalation" patented technology

The invention discloses a silicon-carbon material and a preparation method and application thereof, belongs to the technical field of negative electrode materials, and overcomes the defect of high volume expansion rate of a silicon-based material in the prior art. The silicon-carbon material provided by the invention comprises porous carbon and silicon deposited in porous carbon channels; the porous carbon comprises mesopores and macropores, the pore diameter of the mesopores is greater than 10nm and less than or equal to 50nm, and the pore diameter of the macropores is greater than 50nm and less than or equal to 100nm; based on the total volume of the pores in the porous carbon, the volume fraction of the mesopores is 50%-75%, and the volume fraction of the macropores is 10%-20%; and the silicon deposited in the mesopores and the macropores is a hollow silicon nanotube. Silicon in the silicon-carbon material mainly exists in the form of hollow silicon nanotubes, and during lithium intercalation expansion, since expansion spaces are reserved in the hollow nanotubes, the lithium intercalation expansion of the whole silicon-carbon material is reduced.

The invention provides a lithium supplement composite layer and a preparation method thereof, a lithium supplement method, a pre-lithiated negative pole piece, a secondary battery and an electronic device, the lithium supplement composite layer comprises an interface layer and a lithium supplement layer which are laminated, the interface layer comprises interface particles and a binder, the interface particles comprise a lithium intercalation material and / or a conductive agent, and the binder comprises a lithium intercalation material and / or a conductive agent. The lithium intercalation material is selected from at least one of artificial graphite, natural graphite, hard carbon, a silicon-carbon material, a silicon-oxygen material, lithium titanate, tin and a tin-copper alloy, and the conductive agent is selected from at least one of conductive carbon black, carbon fiber, graphene and a carbon nanotube; the binder is selected from at least one of polytetrafluoroethylene, an ethylene-tetrafluoroethylene copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride and polyoxyethylene; the lithium supplementing layer comprises lithium metal and / or lithium alloy. The lithium supplement composite layer meets the above characteristics, lithium supplement is carried out on the negative pole piece, the first coulombic efficiency of the secondary battery can be improved, the cycle capacity attenuation is reduced, and the energy density of the secondary battery is improved.

The invention provides a preparation method of a hyperbranched polyimide-derived silicon-carbon negative electrode material, which comprises the following steps: S1, preparation of a carbon precursor: mixing 1, 3, 5-tris (4-aminophenyl) benzene and 4, 4 '-(hexafluoroisopropenyl) diphthalic anhydride for reaction to prepare hyperbranched polyimide; s2, preparing porous carbon; and S3, vapor phase silicon carbon deposition. The invention also correspondingly provides a silicon-carbon negative electrode, a lithium ion battery and an electrochemical device. According to the hyperbranched polyimide-derived silicon-carbon negative electrode material, the volume expansion of silicon in the lithium intercalation process is effectively relieved, the active material is prevented from falling off, and the cycling stability of the battery is improved.

The invention provides a graphite composite material, a preparation method thereof and a secondary battery, and relates to the technical field of lithium ion battery negative electrode materials. The graphite composite material comprises an inner core and a shell layer, the inner core comprises metal element doped metal oxide and graphite, the metal element doped metal oxide is embedded between sheet layers of the graphite, the shell layer comprises multi-walled carbon nanotubes and amorphous carbon, and the multi-walled carbon nanotubes are distributed in the amorphous carbon in a 3D net shape. According to the invention, by introducing the doping element, the lithium intercalation active sites of the metal oxide are increased, so that the lithium storage performance of the graphite composite material is improved; through the construction of a core-shell and intercalation structure, the volume expansion of the metal oxide is inhibited, so that the cycling stability of the graphite composite material is improved.

The invention provides a silicon-based composite material, a preparation method thereof and a negative plate. The silicon-based composite material comprises silicon-based composite material particles, the silicon-based composite material particles comprise a porous substrate and silicon particles loaded in pores of the porous substrate, the silicon particles comprise at least one silicon nanoparticle and an oxygen-enriched layer at least partially coating the silicon nanoparticle, the oxygen-enriched layer is made of SiOx, x is more than 0 and less than or equal to 2, and x is more than 0 and less than or equal to 2. And the oxygen content in the oxygen-rich layer is in gradient change along the direction from the center to the surface of the silicon nanoparticle. According to the silicon-based composite material provided by the invention, the plurality of silicon particles taking the silicon nanoparticles as the core and the oxygen-enriched layer as the shell are loaded on the porous substrate, and the oxygen content in the oxygen-enriched layer is in gradient change, so that the conductivity of the silicon-based composite material is improved; moreover, the volume expansion of silicon in the lithium intercalation process can be relieved by utilizing the oxygen-enriched layer with the gradient change of the oxygen content, the expansion rate of the electrode is reduced, and the cycle performance of the battery is further improved.

A hard carbon material, having a first characteristic peak from 15° to 35° and a second characteristic peak from 25° to 28° in an X-ray diffraction pattern of the hard carbon material. A starting position of the first characteristic peak is A°, an ending position of the first characteristic peak is B°, and B−A≥8°. A peak intensity of the first characteristic peak is I1, a peak intensity of the second characteristic peak is I2, and 0.1≤I2 / I1≤3.0. When a negative electrode plate prepared using the hard carbon material as an active material is subjected to charge and discharge test with lithium metal as a counter electrode to obtain a differential capacity curve, the negative electrode plate has four reversible lithium intercalation peaks and three or four reversible lithium deintercalation peaks within a voltage range of 0 V to 0.4 V.

The invention provides a three-dimensional conductive binder, a negative plate, a secondary battery and a preparation method, and relates to the technical field of secondary batteries, the three-dimensional conductive binder comprises a high-molecular polymer and a carbon-based conductive agent; the high-molecular polymer comprises polyesteramide; the polyesteramide has a three-dimensional bonding network; the polyesteramide is prepared from polyamide acid and polyhydric alcohol through vacuum in-situ polymerization; the number of hydroxyl groups in the polyhydric alcohol is 3 to 6; the number of carbon atoms between hydroxyl groups at two ends of the polyol is 3-8; the carbon-based conductive agent is grafted on the polyesteramide through a chemical bond. According to the three-dimensional conductive binder provided by the invention, the volume effect of the silicon-based material in the lithium intercalation process is bound through the effects of hydrogen bonds and the like, so that the expansion of the silicon-based negative electrode material is effectively inhibited, and the cycle performance of the battery is improved.

The invention provides a sandwich structure MCMB-Si-C silicon-carbon negative electrode material and a preparation method and application thereof.The preparation method comprises the steps that 1, pitch serves as a raw material to prepare mesocarbon microbeads, by means of solid-liquid interface pushing force in the mesocarbon microbead growth process, uniform attachment of nanometer silicon to the surfaces of the mesocarbon microbeads is achieved through a one-step self-assembly method, and the mesocarbon microbeads are formed; the MCMB (at) Si silicon-carbon negative electrode material taking the mesocarbon microbeads as the core is obtained. And (2) coating the surface of the silicon-carbon negative electrode material with a layer of carbon material to construct the MCMB-Si-C silicon-carbon negative electrode material with a sandwich structure, and forming a compact carbon layer on the outermost layer after high-temperature carbonization treatment by using a liquid-phase coating process, so that the double functions of a buffer layer and a conductive layer can be achieved. The composite material is composed of mesocarbon microbeads as a core, nano silicon as an intermediate layer and a compact carbon layer as an outermost layer. The sandwich type buffer structure effectively improves the volume change of the negative electrode in the lithium intercalation / lithium removal process, endows the silicon-carbon negative electrode material with the sandwich structure with excellent cycle stability and rate capability, and is beneficial to formation of a more stable solid electrolyte membrane.

The invention discloses a high-cycle-performance aqueous battery, which comprises an aqueous electrolyte, a negative electrode, a first positive electrode and a second positive electrode, wherein the first positive electrode and the second positive electrode are positioned on two sides of the negative electrode, and a first diaphragm and a second diaphragm are respectively arranged between the first positive electrode and the negative electrode and between the second positive electrode and the negative electrode; the battery is provided with an electromagnetic valve, the electromagnetic valve is electrically connected with the first positive electrode and the second positive electrode to control switching of the positive electrodes in the charging and discharging loop, and every time discharging and charging circulation are completed, the electromagnetic valve switches the electrode connection relation, and the first positive electrode and the second positive electrode are alternately connected into the charging and discharging loop. Switching of the two positive electrodes in the aqueous battery is accurately controlled through the electromagnetic valve, a positive-negative battery structure is formed in real time, the double positive electrodes alternately perform lithium removal-lithium intercalation reaction, excessive Li intercalation or insufficient positive electrode reduction caused by long-term charging and discharging of a single positive electrode is avoided, the structural stability of the positive electrode material is improved, and the service life of the battery is prolonged. The cycle life and the electrochemical performance stability of the aqueous battery are obviously improved.

The invention relates to the technical field of batteries, in particular to a silicon-carbon composite material and application thereof. The silicon-carbon composite material comprises a porous carbon material and nano silicon particles positioned in pores of the porous carbon material, in a dQ / dV curve of lithium intercalation for the first time of the silicon-carbon composite material, the ratio of the intensity value of a lithium intercalation peak at 0.30-0.45 V to the strongest peak value within 0-0.25 V is less than 0.05. The silicon-carbon composite material has the advantages of high compressive strength, high charge-discharge capacity and good cycle stability.

The invention relates to a negative electrode material and a preparation method thereof, and a lithium ion battery, the negative electrode material comprises a carbon matrix and an active substance, the carbon matrix has pores, and at least part of the active substance is distributed in the pores of the carbon matrix. The carbon dioxide in the pores of the carbon matrix in the negative electrode material can be quickly dissolved in the electrolyte and promote the electrolyte to enter the pores of the negative electrode material, and meanwhile, in the lithium intercalation process, the dissolved carbon dioxide can reduce the decomposition rate of FEC and reduce the formation of a loose and irregular SEI film, so that the lithium intercalation efficiency is improved. And the binding effect of fluorine in the lithium fluoride SEI film and lithium in the lithium silicon alloy is improved, so that the capacity and the first effect of the negative electrode material are improved.

The invention discloses a silicon-carbon composite material containing a covalent organic framework material coating layer for a negative electrode of a lithium ion battery and a preparation method of the silicon-carbon composite material. The silicon-carbon composite material containing the covalent organic framework material coating layer comprises a silicon-based / porous carbon composite material and the covalent organic framework material coating layer coating the surface of the silicon-based / porous carbon composite material, and the covalent organic framework material is a crystalline porous polymer material formed by connecting organic molecules through covalent bonds. The catalyst has the advantages of low specific surface area and good thermal stability, and contains a regular pore channel structure with adjustable pore diameter. The method has the advantages that the volume expansion of the silicon-carbon composite material in the lithium intercalation and deintercalation process is inhibited, and the mechanical property of the silicon-carbon composite material is improved, so that the cycle performance of the material is improved, and the first coulombic efficiency is improved.

The application relates to the technical field of lithium / sodium ion battery negative electrode materials, in particular to a phosphorus-based negative electrode material with a solid electrolyte interface and a preparation method and application thereof, the method comprises the following steps: mixing phosphorus powder, a carbon material and a metal fluoride and performing ball milling to obtain a composite negative electrode material; and performing sieving treatment on the composite negative electrode material to obtain the phosphorus-based negative electrode material. According to the application, the metal fluoride is doped to in-situ construct a solid electrolyte interface with high strength and high lithium ion / electron transmission, so that the cycle stability and the rate performance of the battery are improved. When the lithium ion battery is discharged, the metal fluoride can in-situ construct a solid electrolyte interface rich in fluorinated lithium with high Young's modulus and lithium-metal alloy with high ion / electron conductivity on the surface of phosphorus-carbon particles prior to phosphorus-carbon lithium intercalation, the solid electrolyte interface can enhance the strength of the solid electrolyte interface by means of the fluorinated lithium with high Young's modulus, so as to inhibit the expansion of the phosphorus-carbon negative electrode, and the cycle stability is improved.

The invention discloses a composite carbon-coated graphite negative electrode material and a preparation method and application thereof.The negative electrode material is of a coating structure, an inner core comprises graphite, a coating layer comprises graphitized carbon and hard carbon, the graphitized carbon and the hard carbon are evenly distributed, more lithium intercalation active sites are provided for the surface of the graphite, and meanwhile the surface of the graphite is coated with the composite carbon. And the high-temperature performance deterioration of the material is effectively reduced. According to the negative electrode material, the epoxy asphalt is used as a coating agent raw material, a resin-based component and an asphalt component which exist in the epoxy asphalt at the same time are subjected to carbonization treatment and graphitization treatment to obtain a hard carbon and graphitized carbon composite carbon coating layer which is uniformly distributed, and compared with coating of hard carbon or soft carbon, the composite carbon coating layer has the advantages that the coating effect is good; and the material has excellent quick-charging performance and good high-temperature performance. When the lithium ion battery electrolyte is applied to a lithium ion battery, the dynamic performance test shows that lithium is not separated out or slightly separated out, and the electrolyte has excellent fast charging performance; the capacity recovery rate can reach 80.3-91.9% after being stored for 100 days at the high temperature of 60 DEG C, and the high-temperature performance is good.

The internal temperature distribution of a battery cell is assessed by acquiring lithium content at different positions on a negative electrode plate of a target battery cell and a corresponding test environment temperature and determining lithium intercalation reaction rate ratios at different positions based on the lithium content at different positions on the negative electrode plate. Temperature values at different positions on the negative electrode plate are calculated based on the lithium intercalation reaction rate ratios at different positions on the negative electrode plate and the test environment temperature. An internal temperature distribution assessment result of the target battery cell is determined based on the temperature values at different positions on the negative electrode plate. Temperature gradients at different positions can be calculated by measuring the lithium content on a lithium-intercalated negative electrode plate, so that the internal temperature distribution assessment result of the battery cell can be obtained.

The invention provides a lithium ion battery and a power utilization device, the lithium ion battery comprises a positive plate, the positive plate comprises a positive current collector and a positive active material coated on at least one surface of the positive current collector, and the positive active material at least comprises one secondary sphere particle; the diameter of the secondary spherical particles is D, the secondary spherical particles are divided into a region A and a region B in the three-dimensional space, the region A is a spherical region with the center of the secondary spherical particles as the sphere center and the diameter is m, m is equal to 0.382 D, and the region B is the part, except the region A, of the secondary spherical particles; the order degree of the area A and the area B meets the condition that RA is smaller than RB. Secondary sphere particles are divided into a region A and a region B, RB is set to be greater than RA, the region B with high order degree is easier to form a lithium ion channel, the lithium intercalation performance is improved, lithium ions in an electrolyte preferentially contact the region B and are rapidly and orderly introduced through the lithium ion channel, and the rate capability of the battery is improved; the area A is used for improving the structural stability and guaranteeing the cycle performance of the battery.

The invention belongs to the technical field of lithium battery waste recovery, and particularly relates to a method for extracting a lithium element from a waste battery. According to the method, the waste battery is charged firstly, so that lithium is gathered to the negative electrode graphite, the lithium is embedded into the graphite, then crushing treatment is carried out underwater, heat is absorbed through a large amount of water to isolate oxygen, and the thermal runaway phenomenon caused by electrification in the crushing process is avoided; during crushing, the graphite negative electrode can be desorbed into water from a pole piece, and the graphite negative electrode is separated out and lithium ions embedded in the graphite negative electrode are brought out in a froth flotation manner by utilizing the hydrophobicity of graphite; and subsequently, acid liquor is used for recycling the lithium element through leaching. According to the method disclosed by the invention, most lithium is recovered by adopting a mode of pre-extraction and small part of lithium is subjected to post-extraction, the pure lithium element is preferentially extracted in a simple mode, and the condition of lithium loss caused by post-extraction of lithium is reduced; and the raffinate is recycled, so that the consumption of other materials is reduced while the lithium recovery rate is increased. The method is simple, and the recovery rate of lithium is high.

The embodiment of the invention discloses a negative electrode and a preparation method thereof and a battery, the negative electrode comprises a silica material, a first material and a binder, the first material comprises MXene of a lithium intercalation layer and an elastic polymer electrolyte coating layer coating the surface of the MXene of the lithium intercalation layer, and a three-dimensional elastic network with ionic conductivity is constructed by adhering a binder to the periphery of the silica material. Under the combined action of the network and MXene particles of a rigid lithium intercalation dispersed in the network, the huge volume expansion of the silica material in the circulation process can be effectively bound and buffered, and the integrity and stability of the electrode structure are maintained. Meanwhile, the elastic polymer electrolyte is used as an ionic conductor, so that an additional path is provided for storage and transmission of lithium ions in lithium intercalation MXene; and meanwhile, the MXene of the lithium intercalation layer can also be used as a lithium supplementing material, so that the first coulombic efficiency of the battery is effectively improved.

A battery that cycles lithium ions includes a negative electrode, a positive electrode spaced apart from the negative electrode, and a gel polymer electrolyte disposed between and configured to provide a medium for the conduction of lithium ions between the negative electrode and the positive electrode. The positive electrode includes a high-voltage electroactive material formulated to undergo lithium intercalation and deintercalation. The gel polymer electrolyte includes an aliphatic polyester, a lithium salt, and an ionic liquid. The aliphatic polyester includes a substituted or unsubstituted poly(ethylene carbonate) (PEC). The lithium salt includes lithium sulfonylimide, lithium borate, or a combination thereof. The ionic liquid includes substantially equimolar amounts of a cation and an anion, with the cation including a complex of lithium (Li+) and an ethylene glycol dimethyl ether, an imidazole ion, or a combination thereof, and the anion including a sulfinate ion, a borate ion, or a combination thereof.

The invention provides a positive active material, a method for preparing the same, and a positive active material layer. By controlling the sintering condition and composition of the positive electrode active material, the positive electrode active material having a controlled specific surface area, the preparation method thereof, and the positive electrode including the same may have an optimized density of the positive electrode active material, thereby maximizing output characteristics of an all-solid-state battery including the same. The positive electrode active material may include a lithium composite oxide capable of intercalating or deintercalating lithium, in which a ratio (Sm / Sc) of a specific surface area (Sm) measured based on a Brunauer-Emmet-Teller (BET) method to a specific surface area (Sc) calculated based on a particle size distribution (PSD) analysis result is within a first range of 2.0 to 3.3.

The invention relates to a self-supporting alloy negative electrode and a preparation method thereof. The negative electrode is a composite material containing metal, an intermetallic compound and a high polymer material. The preparation method comprises the following steps: firstly, preparing a copper foil with a circular through hole structure through a direct current electrodeposition method, then coating a layer of polymer insulating film on one surface of the copper foil, and then depositing a layer of dual-phase alloy negative electrode active material on the other surface of the copper foil through a double-target co-sputtering method. And dropwise adding a colloidal electrolyte on the surface of the active material, curing at a certain temperature, and finally pre-embedding lithium to obtain the final alloy negative electrode. The prepared alloy negative electrode has outstanding electrochemical performance: the gram volume is higher than 1000mAh / g, the lithium intercalation and deintercalation potential is lower than 0.5 V (Vs Li / Li < + >), and the alloy negative electrode has high volume and mass energy density; the cycle life is long, and the material can stably circulate for more than 100 cycles; the growth of lithium dendrites can be inhibited, the risk of short circuit is avoided, and the safety is high. The preparation method of the electrode material is simple, and industrial large-scale production can be realized.

A secondary battery (100) comprises a negative electrode sheet (10), wherein the negative electrode sheet comprises a current collector and a first active material layer (2); the first active material layer (2) is arranged on at least one surface of the current collector; and the first active material layer (2) comprises a silicon-based material and a solid electrolyte, and the solid electrolyte is at least partially bonded to the surface of silicon in the silicon-based material. In the secondary battery and the electric device, the solid electrolyte is at least partially bonded to the surface of silicon in the silicon-based material; therefore, the problem of the expansion of the silicon-based material can be ameliorated, and the structural integrity and structural stability of the negative electrode sheet (10) can be enhanced. Moreover, compared with a binder-coated silicon-based material in the prior art, due to the utilization of the solid electrolyte, the lithium intercalation capability of the silicon-based material can be improved, and the ion conduction rate of the negative electrode sheet (10) can be improved, that is, the problem of deteriorated dynamic properties of the secondary battery caused by a binder-coated silicon-based material can be ameliorated.

The invention relates to the technical field of lithium batteries, in particular to a preparation method of a high-first-efficiency and high-conductivity silicon monoxide negative pole piece, which comprises the following steps: 1, improving the conductivity of silicon monoxide powder in a fluorine-doped carbon coating manner, and enhancing the structural stability of an SEI film formed by the first charge and discharge of the silicon monoxide negative pole piece; 2, through a powder pre-lithiation mode, the lithium content of the silicon monoxide powder is improved, and the initial coulombic efficiency of the silicon monoxide negative electrode plate is enhanced; 3, by introducing a polymer binder containing a conjugated structure, the ion / electron conductivity of the silicon monoxide negative electrode plate is improved, the resistance of the negative electrode plate is reduced, and the volume expansion of silicon monoxide particles in the lithium intercalation and deintercalation process is buffered; and 4, mixing the powder prepared in the step 2 with the conductive polymer binder prepared in the step 3 to obtain the silicon monoxide negative pole piece. The negative pole piece prepared by the preparation method disclosed by the invention has relatively high first coulombic efficiency, relatively high conductivity and relatively high rate capability.

The invention relates to a method for synergistically improving electrochemical performance of a lithium nickelate positive electrode material by virtue of a plurality of trace elements, which is characterized in that a particle body crystal structure of the material is strengthened by virtue of a synergistic effect of the trace elements, and the surface is subjected to in-situ conversion to form a coherent rock salt phase surface layer, so that Li / Ni cation mixing and surface residual alkali amount are reduced, and the electrochemical performance of the lithium nickelate positive electrode material is improved. Structural distortion and surface harmful side reactions in the lithium intercalation and deintercalation process are effectively inhibited, so that the electrochemical performance such as the specific capacity, the cycle life, the rate and the high-temperature cycle stability of the material is improved. The stoichiometric formula of the lithium nickelate positive electrode material is Li < 1.05-x > Ni < 1-y-z > A < x > B < y > C < z > O < 2 >, the specific capacity can reach 250 mAh / g or above, the 10 C specific capacity reaches 158 mAh / g or above, the capacity retention ratio is 80.34% after charging and discharging circulation for 500 weeks at the normal temperature under the current rate of 1 C, and the capacity retention ratio is 62.83% after charging and discharging circulation for 500 weeks at the temperature of 55 DEG C. The positive electrode material has the characteristics of no cobalt or manganese, high specific capacity, long cycle life, good rate and high-temperature performance and the like, and has a wide application prospect in high-specific-energy lithium ion batteries in the fields of unmanned aerial vehicles, artificial intelligence, electric automobiles and the like.

The invention relates to the technical field of lithium battery negative electrode materials, and particularly discloses a composite graphite negative electrode material and a preparation method and application thereof.The composite graphite negative electrode material comprises an inner core and a coating layer coating the outer side of the inner core, the inner core is graphite, and the coating layer is graphite. And the coating layer is a carbon layer doped with metal M atoms and oxide nano-clusters / particles of the metal M atoms. The coating layer doped with the metal M atoms and the oxide nano-clusters / particles of the metal M atoms can effectively reduce the diffusion barrier of Li < + >, and the lithium intercalation potential (greater than 0.3) of MOx is higher than that (0.02-0.2 V) of graphite, so that the probability of precipitation of Li < + > on the surface of the graphite due to polarization is reduced, and the risk of lithium precipitation is reduced.

The application belongs to the technical field of electrode materials, and particularly relates to a silicon-carbon negative electrode material based on vertical graphene and a preparation method and application thereof. The method comprises the following steps: preparing mixed slurry containing nanosilicon-based material and micrometer graphite material; performing spray drying treatment to obtain silicon-carbon composite particles; performing sintering treatment on the silicon-carbon composite particles under a protective atmosphere, and performing screening to obtain micrometer porous silicon-carbon particles; and performing chemical vapor deposition treatment on the porous silicon-carbon particles under the condition of containing carbon source gas and etching atmosphere, to obtain the silicon-carbon negative electrode material based on vertical graphene. Vertical graphene nanosheets are grown in the internal pores and outer surface of the porous silicon-carbon particles, to form a developed and robust conductive network with high mechanical strength and structural stability, and to relieve the volume expansion of the silicon-based material in the lithium intercalation process. Meanwhile, the problem of low bulk density of the silicon-based material is solved in the secondary granulation process, the volume expansion effect of the silicon-based material is inhibited, and the rate charge-discharge performance is improved.

A lithium extraction and deintercalation electrode plate and a manufacturing method therefor and a use thereof. An active layer of the lithium extraction and deintercalation electrode plate comprises a lithium-rich positive electrode material after delithiation and alginate. The alginate is used for improving the hydrophilicity of the electrode plate, and at the same time, a hydrogel structure is produced by the alginate and dissolved-out metal ions under the gelation effect generated in a water flow environment during a lithium intercalation and deintercalation cycle, so that lithium ion transport can be enhanced; the mechanical properties of the electrode plate can be improved, and the stability thereof in all directions can be maintained, thereby solving the problems of falling-off of substances and poor stable lithium-ion transport capability caused by insufficient mechanical stability of the electrode plate during long-term use.

An embodiment of the present application discloses a method for detecting the lithium intercalation content of a negative electrode sheet. The detection method does not require the production of a button cell. After the battery cell is charged or discharged, the battery cell is disassembled to take the negative electrode sheet for XRD testing, avoiding the problem of large deviation in the detection result caused by the loss of material during the cutting of the negative electrode sheet for the production of the button cell. Through the XRD spectrum information, from the LiC6 stage of the negative electrode sheet to the peak intensity change of the LiC 12 stage, combined with the theoretical specific capacity per gram of the carbon material, the graphitization degree of the carbon material, and the N / P value of the battery cell, the actual specific capacity of the carbon material is calculated. The lithium intercalation content of the negative electrode sheet is calculated based on the actual specific capacity of the carbon material. It is not affected by the polarization during the charge and discharge of the battery cell, and the result deviation is within the range of 0-5%. The test method is simple to operate, removing the unstable factors in the button cell test. By utilizing the phase change that occurs during the lithium intercalation process of graphite, the intrinsic change of the crystal structure is characterized by XRD testing, the test result is more intuitive, the detection accuracy is high, the detection time is short, and the detection efficiency is high.

An electrochemical cell has a cathode active material selected from mixed lithium transition metal oxides containing Mn and at least one second transition metal; lithium intercalating mixed oxides containing Ni, Al and at least one second transition metal; and lithium metal phosphates, wherein the outer surface of the particulate cathode active material is at least partially coated with an oxide selected from transition metal oxides, lanthanide oxides, and oxides of metals and half metals of groups 2, 13, and 14 of the periodic system; and an electrolyte composition containing at least one silyl ester phosphonate of formula (I)and at least one silyl ester phosphonate of formula (II)

The invention discloses an in-situ characterization method of graphite electrode microstructure stress in an electrochemical process. The in-situ characterization method comprises the following steps: measuring microstructure three-dimensional strain evolution information in situ by adopting a spectrum comprehensive technology; calculating modulus evolution of the typical lithium intercalation structure by adopting DFT (Discrete Fourier Transform); and establishing an electrochemical induced stress characterization model based on microstructure strain and modulus. The invention provides a novel electrochemical induced microstructure stress characterization method based on experiments, simulation and modeling, key factors such as microstructure anisotropy, strain types, modulus nonlinearity and the like are considered, the accuracy of mechanical description is ensured, and comprehensive characterization of microstructural mechanics is realized. Based on the provided microstructure stress characterization method, the important function of graphite electrode microstructural mechanics in the lithium storage process can be analyzed, meanwhile, the method can be further popularized to other layered electrode materials and sodium and potassium storage systems, and an important means is provided for mechanical-electrochemical coupling analysis.