CN-121978549-A - Internal resistance-capacity-self-discharge three-dimensional consistency grading method and system for aviation cylindrical quasi-solid battery cell and matching rule

Abstract

The invention discloses an internal resistance-capacity-self-discharge three-dimensional consistency grading method, a system and a matching rule for aviation cylindrical quasi-solid lithium battery cells, and aims to solve the technical problem that aviation battery packs still need to obtain extremely high consistency under the same batch production condition that only thousands-to-thousands-of battery cells are needed at a time and the candidate range is far smaller than the vehicle standard million-level so as to meet the repeatability of intrinsic safety and navigability verification. The method comprises the steps of pre-grouping an empty cell quality standard narrow window, multi-stage liquid injection and liquid supplement closed loop taking a liquid injection later quality drop point as a control target, vacuum degassing infiltration, in-situ solidification of an A/B dual-component flame-retardant quasi-solid electrolyte and consistency control of a mixed LLZO ceramic electrolyte, and three-stage gating classification of steady-state open-circuit voltage and internal resistance gating, high-temperature standing self-discharge gating and precise capacity-division gating after formation, so as to form a three-dimensional classification result of an internal resistance label, a capacity label and a self-discharge label, and generate a grouping scheme according to rules of parallel priority matching internal resistance, serial priority matching capacity and self-discharge. The system provides a threshold window, an upper limit of closed loop times, a judging rule, a quadratic or piecewise quadratic fit model form and an overall process traceability field, and can calculate, verify and audit consistency manufacture and matching. The invention can obviously reduce the risk of parallel circulation and hot spots, inhibit the effect of the serially connected casks and improve the consistency and safety margin of the high-voltage large serial-parallel aviation battery pack.

Inventors

• MA XIN

Assignees

• 深圳市欧风航科飞机工业有限公司

Dates

Publication Date

20260505

Application Date

20251221

Claims (1)

1. 1. The method is characterized by comprising the steps of pre-screening, quality closed-loop liquid injection and liquid supplementing, degassing infiltration, A/B bi-component in-situ solidification, three-stage gate control grading and group-oriented matching rule generation, wherein the quality closed-loop liquid injection and liquid supplementing take a quality falling point after liquid injection as a control target, a closed loop is formed through multi-stage addition and repeated weighing, at least two-stage threshold windows are set, the upper limit of closed loop times is set, the quality of the injected liquid is judged to be qualified when the quality deviation delta m is converged in a second threshold window, otherwise abnormal interception is triggered, the three-stage gate control grading sequentially comprises forming a post-formation steady-state open-circuit voltage and internal resistance gate control, high-temperature static self-discharge gate control and precise capacity-division gate control, a three-dimensional grading result of an internal resistance label, a capacity label and a self-discharge label is obtained, and the matching rule is generated by taking internal resistance, serial priority matching capacity and self-discharge as basic principles. The method according to the second claim, wherein the pre-screening comprises establishing a reference distribution of empty cell quality and classifying the cells with similar active material effective loads into the same candidate group according to a narrow window, wherein the width of the narrow window is determined by the reverse thrust of the target capacity consistency and is used for reducing the initial dispersion of the convergence of the subsequent injection and the solidification consistency. The third method is characterized in that the method comprises three stages of coarse addition, fine addition and micro-compensation according to the first method, wherein the step of the coarse addition stage is set according to the proportion of the quality of the target injection liquid and is used for quickly approaching a target interval, the step of the fine addition stage is converged to a smaller proportion so that the quality deviation falls into a first threshold window, and the micro-compensation stage adopts multiple small-step addition and fixed waiting complex weighing so that the quality deviation falls into a second threshold window, and the second threshold window is smaller than the first threshold window. The method according to the fourth claim, characterized in that a non-linear mapping fitting model for fluid replacement decisions is provided, the quality deviation Δm being mapped to capacity deviation estimates Δq_est and/or self-discharge deviation estimates Δsd_est, the fitting model being in the form of a quadratic function or a piecewise quadratic function and having model version numbers and application scope fields for auditing and updating under different batches, different process windows. The method according to the fifth claim, wherein in the a/B two-component in-situ curing step, the a component comprises in-situ polymerizable monomer or oligomer and flame retardant synergistic component, the B component comprises crosslinking agent and/or initiating system and/or synergistic curing component, the a and B are mixed within a specified ratio range to form a quasi-solid network within a controlled temperature window, and the mixed rheological index window, gelation time window and curing temperature integral are used as consistency tracing fields. The method according to the sixth claim, wherein solid ceramic electrolyte particles are mixed in the quasi-solid system to improve the withstand voltage and inhibit dendrites, the solid ceramic electrolyte particles are garnet type lithium lanthanum zirconium oxide LLZO or doped variants thereof, the particle size distribution and the addition amount are in a specified range, and shearing conditions and upper limit of aggregation index are set in the dispersing process, and the dispersing conditions and the aggregation index are used as consistency tracing fields. The method of claim seven, wherein the high temperature static self-discharge gating in the three-stage gating hierarchy includes placing the cells in a specified high temperature window and standing for a specified duration window, measuring open circuit voltage drift and self-discharge equivalent index and combining with internal resistance change for rejecting potential micro-shorts or side reaction anomalies. The method according to the eighth claim, wherein the whole process tracing field system is built, and the tracing field system at least comprises a hollow cell quality standard, a liquid injection target quality, a quality deviation delta m sequence, a threshold window version number, a fitting model version number, a degassing infiltration range number, a curing temperature integral, a steady-state open circuit voltage after formation, an internal resistance test result, an open circuit voltage drift and self-discharge equivalent index after high-temperature rest, a precise capacity value and coulombic efficiency, and a group matching rule output result, which are used for airworthiness verification, quality audit and failure tracing. The three-dimensional consistency grading system for implementing the method according to any one of the first to eighth claims is characterized by comprising a high-precision weighing unit, a micro-injection and fluid-filling closed-loop unit, a degassing infiltration unit, an in-situ curing temperature control unit, an electrical property acquisition and grading unit and a traceability database and control software system, wherein the control software system comprises a threshold window management module, a closed-loop fluid-filling control module, a nonlinear mapping fitting module, a three-stage gating grading module, a selection rule generation module and a traceability audit module.

Description

Internal resistance-capacity-self-discharge three-dimensional consistency grading method and system for aviation cylindrical quasi-solid battery cell and matching rule The invention relates to a sorting, grading and matching method of aviation cylindrical quasi-solid lithium battery cells (such as 18650 and 21700) before assembly in groups, and particularly belongs to the technical field of manufacturing and quality control of battery cell consistency evaluation, grading, matching rule, group verification. The aviation battery pack and the automobile power battery have fundamental difference in use boundary that the sensitivity of aviation scene to unit energy quality, unit volume power, wide temperature multiplying power performance and failure result is higher, and meanwhile, more severe requirements are put on 'intrinsic safety' and 'provable consistency'. So-called consistency is not only seen by a single index of capacity or voltage, but rather requires that within the same SOC window, key variables such as equivalent internal resistance, polarization behavior, available capacity, standing voltage drift, self-discharge rate, thermal response and aging rate of the battery cells are statistically controllable and traceable. If the consistency of the electric core is insufficient, local electric core reaches the voltage/temperature threshold value in advance in the same serial-parallel structure, the triggering protection strategy, the unavailable capacity and the accelerated differentiation of service life can be realized, the triggering of the thermal runaway of the monomer and the rise of the risk of heat spreading can be caused in extreme cases, and the tolerance of the risk is far lower than that of a ground vehicle in aviation application. The existing automotive power cell industry can achieve higher uniformity, and an important premise is "ultra-large scale, long period, strong coupling manufacturing uniformity". Taking a typical high-consistency cylindrical cell in the industry as an example, the consistency foundation is firstly from the uniformity of material sides, namely the particle size and specific surface of a positive and negative electrode main material, the dispersion state of an adhesive/conductive agent, a solvent system, an additive system, the uniformity of diaphragm aperture and coating, the thickness and surface state of copper foil/aluminum foil and the like, and secondly from the uniformity of process sides, namely the large-volume continuous homogenization (such as kiloliter stirring and circulation defoamation), continuous coating and on-line thickness closed-loop control, the consistency of rolling density and rebound, the consistency of cutting burrs and lug sizes, the consistency of winding tension and alignment, the consistency of baking moisture and drying curves, the consistency of liquid injection amount and wetting path, the consistency of standing wetting time, the consistency of formation/partial capacitance current and temperature, and the consistency of sorting criteria. More importantly, automotive cell lines typically run on a statistical scale of "millions of cells in a batch" allowing tail distributions to be rejected or redistributed by multi-stage sorting within a large sample cell, compressing capacity differences, internal resistance differences, voltage differences, etc. into smaller regions. The mode of ultra-large sample cell and multi-level sorting is naturally limited on the aviation battery pack, wherein the number of single-core of the aviation battery pack is often in the thousand-level order (for example, 1800), and millions of continuous homogeneous production like the automobile industry is difficult to maintain for a long time due to model iteration, trial batch, airworthiness evidence obtaining rhythm and the like. The result is that even if the target is the consistency index of the standard automobile battery cell, the aviation battery cell often faces the difficult problems of insufficient selectable range caused by insufficient sample pool, insufficient tail part rejection and hidden difference brought into group caused by insufficient sorting dimension. In the prior art, the cell sorting and assembling generally depends on a plurality of dominant indexes such as open circuit voltage, direct current internal resistance, alternating current impedance, capacity (one or more times of capacity division), self-discharge (standing voltage fall-back), appearance size and the like. The method is characterized in that the domestic and foreign patents largely cover the ideas, but the method is generally more biased to the large-scale manufacturing context of electric vehicles/energy storage, the problem that the 'stronger three-dimensional consistency (internal resistance-capacity-self discharge coupling consistency) required by aviation aiming at solid-state cells and the' approaching large sample pool consistency from small sample pools 'are focus