627 results about "Self-discharge" patented technology

The invention relates to the technical field of supercapacitors, and provides a cement-based supercapacitor, a preparation method and application. The cement-based supercapacitor comprises a cement-based electrolyte and two structural electrodes arranged on the two sides of the cement-based electrolyte. The cement-based electrolyte is prepared from cement, alkali, alkali metal salt, water and an additive, wherein the alkali metal salt comprises lithium salt; each structural electrode is composed of foamed nickel loaded with nitrogen-doped reduced graphene oxide. The lithium salt is added to construct an efficient ionic conductive network, so that the ionic conductivity of the cement-based electrolyte is enhanced, and the electrochemical performance is obviously improved. The reduced graphene oxide in the structural electrode is doped with nitrogen to enhance the electrostatic force between ions and the surface of the electrode, so that the electrochemical stability of the surface of the electrode is improved, and self-discharge is effectively inhibited. By improving an electrolyte and a structural electrode material, a cement-based supercapacitor with specific capacitance and mechanical properties is obtained and is combined with a building structure to realize building energy storage.

The invention relates to the field of lithium battery detection, and particularly discloses a lithium ion battery fault detection method, which comprises the following steps of: firstly, acquiring total current data of a battery pack in real time, and judging the current running state of a battery system according to the total current of the battery pack and the duration time; and when the battery system is in a standing state, calculating the voltage drop rate and the temperature rise rate of each single battery in a preset time window, and comparing the voltage drop rate and the temperature rise rate with corresponding thresholds to realize self-discharge detection and fault identification. And when the battery system is in a charging or discharging state, a deep learning algorithm is further introduced, temperature-pressure coupling time sequence fluctuation characteristics of each single battery are extracted, and temperature-pressure coupling time sequence fluctuation state consistency analysis is performed on each single battery, so that intelligent detection of faults of the single batteries in the charging and discharging process is realized. According to the method, the abnormal temperature and pressure fluctuation of the single battery in the charging and discharging process can be effectively captured, so that early warning and accurate positioning of a fault are realized.

The invention relates to a battery self-discharge characteristic analysis and rapid evaluation method, and aims to improve the precision and efficiency of battery self-discharge performance detection. According to the method, in a set environment stable interval, an instantaneous voltage change sequence and a current perturbation response sequence of a target battery are acquired through micro-load disturbance, and a battery internal resistance dynamic evolution tensor representing dynamic response characteristics in the battery is constructed; extracting local features by applying a multi-scale time window segmentation strategy, forming a feature vector group containing a voltage nonlinear rebound factor and a delay response index, inputting the feature vector group into a trained Bayesian weighted adaptive mapping network, and outputting a battery self-discharge rate estimated value combining a manufacturing batch residual error and temperature offset compensation; performing trend fitting and consistency checking on the estimated value to obtain a battery self-discharge grade evaluation result, and generating a structured detection report containing initial offset, rebound amplitude and estimation confidence; the method can be widely applied to battery production, quality control and performance screening scenes.

The invention discloses a two-phase electrolyte, a preparation method thereof and a liquid energy storage battery system, and belongs to the technical field of electrochemical energy storage. According to the invention, a liquid-liquid double-phase electrolyte is composed of a water-phase electrolyte and an organic-phase electrolyte, wherein the organic-phase electrolyte contains a coupling system of 1-(methyl-decyl)-3-methylimidazolium bromide, tris (methyl-decyl) methyl ammonium bromide and (10-octadecyl) alkyl trimethyl ammonium bromide in a molar ratio of (5-7): (2-4): 1. During charging, positive electrode bromide ions are subjected to an oxidation reaction to generate a bromine simple substance, and meanwhile, the bromine simple substance and a coupling system of the quaternary ammonium bromide compound and the bromine complexing agent provided by the invention form a stable polybromine complex product, so that the polybromine complex product is prevented from being migrated into a water-phase electrolyte, and the purpose of improving the stability of the water-phase electrolyte in the absence of a diaphragm is achieved. The self-discharge reaction of bromine is significantly inhibited at a high temperature exceeding the boiling point temperature of bromine, the coulombic efficiency and energy efficiency of the liquid energy storage battery are improved, the system cost is reduced, and the long-term cycle stability of the liquid energy storage battery is improved.

The invention discloses a slurry electrolysis device and battery production equipment, and relates to the technical field of lithium batteries. As an electrolysis positive electrode and an electrolysis negative electrode are positioned between a slurry inlet and a slurry outlet and are in contact with battery slurry, the electrolysis positive electrode and the electrolysis negative electrode are in contact with the battery slurry; under the condition that the potential applied by a power supply for connecting the electrolysis positive electrode and the electrolysis negative electrode is greater than the oxidation potential of a to-be-electrolyzed metal element or alloy in the battery slurry, the to-be-electrolyzed metal element or alloy in the battery slurry can serve as a micro positive electrode, the surface of the to-be-electrolyzed metal element or alloy is oxidized due to potential difference and is gradually dissolved into ions, and the ions are gradually dissolved along with electrolysis. And large metal elementary substance particles are continuously oxidized, the volume is gradually reduced, and finally, the metal elementary substance particles are completely dissolved into metal ions without discharge risk, so that the removal of the metal elementary substance or alloy to be electrolyzed in the battery slurry is realized, and the self-discharge risk of the battery is reduced.

The invention relates to the technical field of batteries, and discloses a roll core and a battery. The roll core comprises a positive plate, a negative plate and a diaphragm, a groove is formed in a positive active layer of the positive plate, and the groove is at least formed in an arc section, closest to the winding center, of the positive plate, so that the thickness of at least partial region on the arc section of the positive plate is reduced, and the risk that active particles on the positive plate pierce the diaphragm is reduced; according to the present invention, by limiting the ratio p1 / H1 between the thickness p1 of the functional layer of the diaphragm and the depth H1 of the groove to be in the range of 0.02-2, the p1 is in the range of 0.3-10 [mu] m, and the H1 is in the range of 3-40 [mu] m, such that the battery can be reduced to the preset charging cut-off current during the charging process, and the self-discharge rate of the battery can be reduced. And on the basis that the battery can reach a fully-charged state, the liquid retention capacity of the battery can be improved, the cycle performance of the battery is improved, and the battery is ensured to have relatively high volume energy density.

The invention discloses an energy storage battery pack self-discharge abnormity diagnosis method based on short-time charging data, and belongs to the technical field of battery safety monitoring. In order to overcome the defects that an existing method depends on a complete charging and discharging period and is difficult to adapt to a multi-stage variable working condition scene, multi-stage charging data features are extracted, self-adaptive extraction of multi-working condition features is achieved in combination with an auto-encoder, a data driving model fusing GCN-BiLSTM (Graph Convolution-Bidirectional Long Short-Term Memory) is constructed, and a multi-stage variable working condition scene is obtained. According to the method, the RCC (Remaining Charge Capability) of the single battery is accurately estimated, and the RCC of the single battery is accurately estimated. And finally, on the basis of the size, the distribution and the change condition of each single RCC in the battery pack, the overall inconsistency of the battery pack, the SOC inconsistency of the single batteries and the self-discharge fault can be diagnosed. And a guarantee is provided for safe operation of the energy storage system.

The invention discloses a detection device with a power supply self-compensation function and a compensation method thereof. The compensation method comprises the following steps: detecting whether an external power supply is switched on or not; if the external power supply is switched on, judging whether the power supply voltage of the external power supply is higher than the working voltage threshold of the sensor unit through the low-voltage detection circuit; if yes, the foot voltage control switch is switched on, the under-voltage control switch is not switched on, and an external power supply supplies power to the detector detection part; if the voltage is lower than the threshold value, the undervoltage control switch is conducted and the foot voltage control switch is not conducted, the energy storage unit charging and discharging management circuit supplies power to the energy storage voltage detection circuit to enable the energy storage unit power supply control switch to be conducted, and the power is transmitted to the detector detection component through the power supply management circuit for automatic compensation power supply; and if the external power supply is not switched on, the external power supply control switch is not switched on, and the energy storage unit does not self-discharge to supply power to the sensing unit of the detector detection part. According to the invention, automatic compensation when power supply of the detector detection part is insufficient is realized.

The invention discloses a lithium ion battery positive electrode based on a composite positive electrode active material and a preparation method and application thereof, and relates to the technical field of lithium ion batteries. The composite positive electrode active material comprises the following components: LiMnXFe1-XPO4 (X is greater than or equal to 0.4 and less than or equal to 0.6), LiMn2O4, LiNi0. 8Co0. 1Mn0. 1O2, Li2Al2B2O7 and an LLTO / LLZO composite material. According to the invention, LiMnXFe1-XPO4 and LiMn2O4 are taken as main materials, and various positive electrode active materials such as LiNi0. 8Co0. 1Mn0. 1O2, Li2Al2B2O7 and LLTO / LLZO are compounded to construct a positive electrode active material component. In the use process of the battery, multiple positive electrode active materials are combined for use, so that ion conduction can be improved, internal polarization of the battery can be reduced, Mn < 2 + > dissolution can be inhibited, a positive electrode CEI membrane can be optimized, the effect of reducing self-discharge can be achieved, and the stability of high-temperature circulation can be synchronously optimized.

The invention relates to a water-soluble plumbic acid static storage battery. The battery comprises a battery monomer, the battery monomer comprises an electrode plate, a static electrolyte and a container, the electrode plate is inserted in the electrolyte, the electrolyte comprises water-soluble lead salt, acid and water, and the battery monomer further comprises a lead dissolving agent or a structure extending the bottom end of a negative plate to the position below a positive plate. The lead dissolving agent can provide at least one water-soluble redox couple R oxidation and R reduction, and the redox couple electrode potential meets E theta (Pb < 2 + > / Pb) lt; e [theta] (R oxidation / R reduction) [lt]; e theta (PbO2 / Pb2 +). No diaphragm exists, the electrolyte is in a static state, facilities such as a circulating pump are not needed, lead ions are allowed to migrate under the concentration gradient effect, and meanwhile self-discharge caused by convection shuttling of the lead dissolving agent is greatly reduced. In the charging process, lead and lead dioxide can be flatly deposited on the surface of an electrode and can be completely dissolved in the discharging process, the cycling stability is good, and the components can be kept stable for a long time.

A method for estimating a remaining battery life of a non-rechargeable battery of an Internet of Things (IoT) device. The method includes determining an amount of battery capacity used by the IoT device while the IoT device was operating in an active mode, an amount of battery capacity used by the IoT device while the IoT device was operating in a sleep mode, and an amount of self-discharge of the non-rechargeable battery while the IoT was deployed based on temperatures of environments in which the IoT device was located. The method further includes determining an estimated remaining battery life of the non-rechargeable battery based on an initial capacity of the non-rechargeable battery, the amounts of battery capacity used by the IoT device while the IoT device was operating in the active mode and the sleep mode, and the amount of self-discharge of the non-rechargeable battery while the IT was deployed.

Provided are a secondary battery and an electronic apparatus. The secondary battery comprises a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, wherein the negative electrode sheet comprises a negative electrode current collector and a negative electrode material layer located on at least one surface of the negative electrode current collector; the negative electrode material layer comprises a negative electrode active material; the negative electrode active material comprises a silicon-carbon composite material; on a plane formed by the direction of length of the negative electrode sheet and the direction of thickness thereof, the minimum value of an interior angle of an outer contour of a particle with a maximum circumscribed-circle diameter of greater than 10 μm in the silicon-carbon composite material is A°; and the thickness of the separator is B μm, where 488≤A×B≤3600, and 4≤B≤25. The secondary battery has good self-discharge performance, charging rate performance and cycling performance.

The invention provides a gravity energy storage scale expansion method, which belongs to the field of electric energy storage such as gravity energy storage and mechanical energy storage, and comprises the following steps: taking a single-machine gravity energy storage system as a minimum standard module capable of independently running, and realizing capacity linear superposition; more than two parallel energy storage driving devices are configured for the same energy storage weight in each standard module to realize stepped increase and decrease of instantaneous power; a central controller receives a power grid dispatching instruction, load prediction data and renewable energy output prediction data in real time, global power requirements are decomposed into charging and discharging tasks of standard modules through a hierarchical control architecture, and a local unit controller executes a weight stroke smooth switching algorithm and a multi-weight synchronous dispatching algorithm. Power output / input is enabled to be continuous without breakpoints; and boosting the electric energy generated by each standard module to a high voltage level matched with the power grid to complete high voltage level networking. The invention has great advantages in the aspects of safety, service life, self-discharge characteristic, overall operation efficiency and the like.

The invention discloses a battery system self-discharge rate consistency detection method and a related device, and relates to the field of batteries, and the method comprises the following steps: executing a first cycle, namely charging a battery system twice to a first state; standing for a first preset time length, and obtaining a charge state corresponding to each battery cell monomer; controlling the battery system to discharge to a second state to obtain a discharge capacity; and standing for a first preset time length, and obtaining the charge state corresponding to each battery cell monomer. And calculating a first monomer capacity based on the first charge state, the second charge state and the discharge capacity of the battery cell monomer. And executing a second cycle, wherein the second cycle is one more than the first cycle to control the battery system to stand for a third preset duration in the second preset temperature interval. And calculating the self-discharge rate of the battery cell monomer and the self-discharge rate range of the battery system based on the first monomer capacity and the second cycle data. Therefore, whether the self-discharge rate consistency of the battery system reaches the standard or not can be determined.

The invention provides a self-discharge prediction method and device of a battery cell, electronic equipment and a storage medium. The method comprises the following steps: acquiring an initial open-circuit voltage of each battery cell in a target batch of battery cells and a target open-circuit voltage of each battery cell after standing for a target time at a target temperature; based on the target temperature, the target time, the initial open-circuit voltage and the target open-circuit voltage of each battery cell, and the self-discharge prediction model of the target batch of battery cells, screening out a target battery cell from each battery cell; and predicting the self-discharge rate and the open-circuit voltage of the target cell under each temperature condition and each time condition based on the initial open-circuit voltage of the target cell and the self-discharge prediction model. Therefore, according to the self-discharge prediction model constructed according to the change characteristics of the self-discharge rate of the battery cell along with the time and the temperature, the self-discharge type and the self-discharge behavior of the battery cell can be accurately predicted, and the accuracy of battery cell self-discharge prediction is improved.

The application provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises a positive electrode sheet, a separator, a negative electrode sheet and an electrolyte. The positive electrode sheet and the negative electrode sheet are stacked, and the separator is arranged between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet comprises a positive electrode main body part and a positive electrode tab part. The ratio of the long side size to the short side size of the positive electrode main body part is (3-8):1. The negative electrode sheet comprises a negative electrode main body part and a negative electrode tab part. The long side of the negative electrode main body part exceeds the long side edge of the positive electrode main body part by 2-9 mm. The long side of the separator exceeds the long side edge of the negative electrode main body part by 2-10 mm. The electrolyte comprises a solvent. The solvent comprises one or more of dimethyl carbonate and a linear carboxylic acid ester having a structure shown in formula (1). In formula (1), R1 and R2 each independently comprises a C1-C5 alkyl or a halogenated alkyl. The battery monomer has a high energy density, good cycle performance and low self-discharge.

The invention provides a double-phase diaphragm-free zinc-bromine battery electrolyte, a preparation method and application, belongs to the technical field of energy storage batteries, and aims to solve the problems that an organic solvent of an existing double-phase diaphragm-free zinc-bromine battery electrolyte has safety risks, the solubility of active substances is not high, and the service life of the battery is prolonged. And when a specific ionic liquid is used as an organic phase, the bromine fixation function is single. Imidazole bromine salt and zinc bromide are jointly dissolved in water, and an ionic liquid phase and a water phase are formed by adjusting the adding amount of the zinc bromide. The solubility of the bromine species in the ionic liquid phase is far greater than that in the water phase, and the imidazole bromine salt can be complexed with the bromine species to form a polybromine complex, so that the ionic liquid phase can be used as a positive electrode electrolyte of a two-phase zinc-bromine battery. The raw materials of the prepared dual-phase electrolyte all participate in the electrode reaction of the zinc-bromine battery, bromine species are dissolved and fixed in an ionic liquid phase under the condition that other organic solvents or ionic liquid is not introduced, diffusion of the bromine species to a water phase is reduced, and the self-discharge phenomenon of the zinc-bromine battery is reduced. And the preparation method of the electrolyte is simple, greatly simplifies the manufacturing process of the battery, and is easy to popularize and apply.

The embodiments of the present application provide a method, device, storage medium and program product for detecting the self-discharge rate of a battery cell, and relate to the field of battery technology. The method for detecting the self-discharge rate of a battery cell includes: determining a first SOC difference between the SOC value of a battery cell and the SOC value of a reference battery cell when a first detection condition is met; determining a second SOC difference between the SOC value of the battery cell and the SOC value of a reference battery cell and a balanced SOC when a second detection condition is met; determining the self-discharge difference information of the battery cell based on the first SOC difference, the second SOC difference and the balanced SOC; determining the self-discharge rate of the battery cell according to the self-discharge rate test value of the battery cell, the self-discharge difference information of all the battery cells of the battery, or the self-discharge rate test value of the battery cell. The present application improves the accuracy and reliability of the self-discharge rate detection of the battery cell, can improve the stability and safety of the battery cell operation, and enhance the performance and service life of the battery cell.

A method, device, and medium for battery physical self-discharge detection are provided. Related to the field of battery monitoring technology and used to detect whether a battery has physical self-discharge, the present disclosure addresses issues of long testing time and difficulty in implementation with current self-discharge detection practice, provides a battery physical self-discharge testing method, leverages frequency response characteristics of battery physical self-discharge and chemical self-discharge to perform self-discharge detection, and rapidly screens whether the battery has physical self-discharge by monitoring a battery voltage change trend. The testing time is short for determining whether a battery has physical self-discharge. It does not need low-temperature storage, reduces implementation difficulty and cost, and better meets requirements of practical battery self-discharge testing scenarios.

The invention provides a battery, the battery comprises a negative plate, a positive plate and an electrolyte, the negative plate comprises a negative current collector and a negative active layer located on the surface of one side or two sides of the negative current collector, the negative active layer comprises a silicon-based material, and in the negative active layer, the weight ratio of silicon element is 2-45%; the electrolyte comprises difluoroethylene carbonate, fluoroethylene carbonate and a phosphazene compound, and in the electrolyte, the weight ratio of the difluoroethylene carbonate to the fluoroethylene carbonate is 0.002-0.4; the molecular structure of the phosphazene compound comprises cyano groups and phosphorus atoms, and the weight ratio of the phosphazene compound in the electrolyte is 0.1-5%. According to the battery, a firm and flexible SEI film can be formed on the surface of the silicon-based negative electrode, repeated breakage of the SEI film is reduced or even avoided, meanwhile, the concentration of HF can be reduced, the internal short circuit and self-discharge risks of the battery are reduced, and the long-cycle stability and the high-temperature cycle performance are improved.

The invention provides an energy storage lithium ion battery high-temperature storage electrolyte additive, an electrolyte and a battery, and belongs to the technical field of lithium ion batteries, molecules of the electrolyte functional additive contain P = O groups, and oxygen atoms in the groups have high electronegativity and can generate complexation with transition metal ions. In the high-temperature storage process of the lithium ion battery, the complexing action can effectively inhibit the dissolution of transition metal ions and reduce a series of adverse effects caused by the dissolution of the transition metal ions, so that the self-discharge phenomenon of the battery during high-temperature storage is improved, and the high-temperature storage capacity retention rate is remarkably increased; and the performance of the battery in a high-temperature environment is improved fundamentally.

A power storage device according to the present invention comprises: a secondary battery that can be charged and discharged; a control unit that controls charging and discharging of the secondary battery; a voltage detection unit that detects the voltage of the secondary battery; and a battery temperature detection unit that detects the temperature of the secondary battery. The control unit, during stoppage of charging of the secondary battery, calculates a first self-discharge amount of the secondary battery on the basis of an elapsed time from a time point at which charging of the secondary battery stopped and on the basis of the temperature detected by the battery temperature detection unit, calculates a second self-discharge amount of the secondary battery on the basis of a variation in the value of the voltage detected by the voltage detection unit during the elapsed time, and estimates the degree of degradation of the secondary battery on the basis of the first self-discharge amount and the second self-discharge amount.

The invention discloses a lithium ion battery with a thermal runaway prevention and control function and a preparation method, the lithium ion battery comprises a plurality of standard layers and barrier layers, the barrier layers are arranged between any two adjacent standard layers, and each barrier layer comprises a specially-made positive plate, a diaphragm plate and a specially-made negative plate. The content of the first conductive agent in the special positive plate is lower than that of the first conductive agent in the standard positive plate. And the content of the second conductive agent in the special negative plate is lower than that in the standard negative plate. When the temperature of the battery cell rises to the melting point of the diaphragm piece and the insulating film has broken holes, the specially-made positive and negative pole pieces are contacted, the internal resistance of the specially-made positive and negative pole pieces is controlled through the content of the conductive agent to adjust the short-circuit current, and the battery cell reduces the residual electric quantity through controllable self-discharge, so that the residual electric quantity in the battery cell is gently released, violent thermal runaway is avoided, and the service life of the battery cell is prolonged. And the purpose of thermal runaway prevention and control is achieved.

The invention provides a diaphragm combined ceramic coating, a coated diaphragm and a preparation method. The diaphragm combined ceramic coating comprises a diaphragm base membrane, a first coating, a second coating and a third coating, the first coating is coated on the surface of the diaphragm base membrane; the second coating is coated on the surface of the first coating; the surface of the second coating is coated with the third coating; the first coating and the second coating comprise one or more ceramic particles; the third coating comprises one or more organic polymer materials; the thickness range of the first coating is 0.2-2 microns; the thickness range of the second coating is 1-5 microns; the thickness range of the third coating is 0.5-3 microns; the ceramic particles are non-spherical particles, and in practical application, the self-discharge of a battery cell can be reduced, and the porosity of the battery cell can be improved, so that the liquid retention effect of the diaphragm is improved, and the electrical performance and the safety performance of the battery are improved.

The invention relates to a method for improving self-discharge screening capability, and relates to the technical field of lithium batteries. The method comprises the following steps: carrying out primary screening on a battery by adopting an overall differential pressure method; the qualified batteries subjected to primary screening are subjected to secondary screening through a single-tray standard deviation method, the K value mean value of all the batteries on a single tray is calculated and obtained, the single-tray standard deviation method judgment scheme is as follows: standard deviation multiple = (K value-single-tray K value mean value) / standard deviation, the threshold value of the standard deviation multiple is-0.008-0.008, and the threshold value of the single-tray K value mean value is-0.008-0.008. The batteries of which the standard deviation multiples are within the range are judged as qualified batteries; and establishing a reworking process for the screened unqualified batteries, performing re-determination according to a long-term K value standard after standing, re-dividing the unqualified batteries passing the determination into qualified batteries and transferring to the next process, and determining the batteries which do not pass the determination as the unqualified batteries. The lithium battery self-discharge screening method and device have the advantages that the abnormal batteries can be screened out more accurately, and the probability of occurrence of mistaken killing and missing killing in lithium battery self-discharge screening is reduced.

The present invention relates to a positive electrode material for a bromine-based flow battery. The positive electrode uses a conductive current collector as a substrate, and a layered porous carbon nitride material with bromine fixation function is supported on the substrate. The substrate is carbon felt, graphite felt or carbon cloth. The electrode material of the present invention has beneficial characteristics such as simple preparation method, low cost, strong bromine fixation ability, and good chemical stability. The prepared electrode material inhibits the migration and diffusion of bromine, reduces the self-discharge reaction of the battery, effectively improves the capacity retention rate and cycle stability of the bromine-based flow battery, and greatly improves the battery life.

The invention discloses a self-discharge evaluation method, system and equipment for a battery cell system and a medium, relates to the technical field of lithium ion batteries, and aims to quickly and accurately screen out self-discharge of a battery cell. A positive electrode, a negative electrode and a diaphragm of a battery cell system are assembled into a small soft package laminated battery cell, and liquid is injected for capacity grading; carrying out a low-current charging and discharging test under a high-temperature condition, obtaining an SOC-OCV curve, and screening an SOC range; adjusting the battery cell to a target SOC, taking out the positive pole piece and the negative pole piece, packaging the positive pole piece and the negative pole piece, tightening the packaged positive pole piece and negative pole piece to remove gas, placing the packaged positive pole piece and negative pole piece at different temperatures, recording volume change values, and drawing a temperature-volume change value curve; testing voltage values of the battery cell before and after the battery cell is placed at different temperatures under the target SOC, and drawing a temperature-voltage change value curve; and calculating a correlation coefficient of the slopes of the two curves, and carrying out self-discharge screening on the battery cells. According to the method, effective self-discharge screening is carried out in the early stage, rework and the rejection rate in subsequent production can be reduced, and therefore time and cost are saved.

The invention discloses a capacity grading charging and discharging method for a lithium iron phosphate battery, which comprises the following steps of: charging the battery with 0.5 C constant current to 3.65 V after secondary liquid injection and liquid supplement, then charging the battery with the constant voltage of 3.65 V to 0.05 C cut-off current, and standing for 5 minutes; then, 0.5 C constant current is used for discharging to 2.5 V, standing is carried out for 5 min, and the voltage rises again; then the voltage is raised to 2.5 V with the constant current of 0.2-0.3 C, standing is carried out for 5 min, and the voltage rises again; then placing to 2.5 V at a constant current of 0.05-0.1 C, and standing for 5 minutes; and finally, 0.5 C constant current is used for charging until 15% of electric quantity is maintained. Wherein the constant current in the step (2), the step (3) and the step (4) needs to be gradually reduced, namely the current in the step (4) is greater than the current in the step (3) and is less than the current in the step (2). The invention mainly aims to ensure that the electric quantity of a single battery after capacity grading tends to be consistent, improve the voltage consistency, ensure the authenticity of self-discharge data and facilitate the removal of abnormal batteries.

The invention discloses a self-discharge detection method, self-discharge detection equipment, a storage medium and a self-discharge detection system, and the method comprises the steps: obtaining the available equalization frequency of a battery cell and obtaining the effective equalization frequency of the battery cell for each battery cell in a battery pack during each equalization of the battery pack; calculating the self-discharge degree of the battery cell according to the available equalization times and the effective equalization times of the battery cell; when the self-discharge degree of the battery cell meets a preset self-discharge condition, determining that the battery cell is a self-discharge abnormal battery cell; the available equalization times and the effective equalization times of the battery cells can be acquired in real time when the battery pack is equalized each time, so that the self-discharge degree of the battery cells is monitored in real time, additional complex measurement equipment and long-time static observation are not needed by utilizing the existing data in the battery cell equalization process, the detection process is simplified, and the detection efficiency is improved. And the detection efficiency is improved.

The invention provides a lithium metal negative electrode, a battery and a preparation method. Specifically, the lithium metal negative electrode comprises a lithium metal sheet and a first coating located on the surface of the lithium metal sheet; wherein the first coating layer is prepared from MXene modified by polyethylene glycol and-SH. MXene in the first coating has lithium affinity, a conductive network can be formed on the outer side of the lithium metal sheet, and the compatibility of the first coating and the sulfide solid electrolyte can be improved due to the existence of polyethylene glycol and-SH modification, so that the lithium metal sheet can be prevented from being in direct contact with the sulfide solid electrolyte through the first coating; ion conduction is ensured, electron permeation is inhibited, and self-discharge is reduced; in addition, polyethylene glycol enables the first coating to have certain mechanical flexibility, so that the first coating can adapt to volume change in the lithium deposition / stripping process, dendrite growth is inhibited, the cycle life of the battery is prolonged, and the safety of the battery is improved.