CN-122000470-A - Self-adjusting viscosity electrolyte and microfluidic distribution system thereof

CN122000470ACN 122000470 ACN122000470 ACN 122000470ACN-122000470-A

Abstract

The invention provides self-adjusting viscosity electrolyte and a microfluidic distribution system thereof, and relates to the technical field of lithium batteries. The electrolyte base electrolyte, cyclodextrin and self-regulating viscosity additive comprise a four-arm star-shaped block copolymer. The invention utilizes the main and guest actions of the four-arm star-shaped block copolymer and the cyclodextrin to construct a dynamic network, and realizes the dual self-adaptive adjustment of the viscosity of the electrolyte to the temperature and the potential. The system is spontaneously tackified through the temperature-sensitive and electrochemical response arms at high temperature or high pressure to inhibit side reactions, and meanwhile, the ion conduction arms are used for maintaining high-efficiency ion transmission, so that the safety is obviously improved on the premise of not sacrificing the conductivity, and the technical contradiction between the inhibition of thermal runaway and the guarantee of quick charge dynamics is effectively solved.

Inventors

ZHANG LINGLI
LIN YILUN
ZHANG YUHUI
XIA XINDE

Assignees

广州鹏辉能源科技股份有限公司

Dates

Publication Date: 20260508
Application Date: 20260209

Claims (10)

1. A self-regulating viscosity electrolyte, wherein the electrolyte comprises a base electrolyte, cyclodextrin and a self-regulating viscosity additive; The self-regulating viscosity additive comprises a four-arm star-block copolymer; the four-arm star-shaped block copolymer has three functional arms, namely Wen Minbei, an electrochemical response arm and an ion conduction arm; Wherein Wen Minbei is a polymer segment having a low critical solution temperature; the electrochemical response arm contains a ferrocene group; The ion conduction arm is a polyether chain segment.
2. The self-regulating viscosity electrolyte according to claim 1, wherein Wen Minbei is a poly N-isopropylacrylamide segment and/or, The ion conduction arm is a polyethylene oxide chain segment and/or, The electrochemical response arm is a polyethylene oxide chain segment containing a ferrocene side group, and/or, The low critical dissolution temperature of the temperature sensitive arm is 30-35 ℃ and/or, The electrochemical response arm is in an oxidized state and hydrophobic aggregation occurs at a potential above 4V, and/or, Based on the total weight of the electrolyte, the mass percentage of the self-adjusting viscosity additive is 5-15 wt%.
3. The self-regulating viscosity electrolyte of claim 1, wherein said base electrolyte comprises a lithium salt and an organic solvent; Preferably, the lithium salt comprises lithium hexafluorophosphate; Preferably, the organic solvent comprises ethylene carbonate and ethylmethyl carbonate; Preferably, the volume ratio of the ethylene carbonate to the ethylmethyl carbonate is 2:8 to 4:6.
4. The self-regulating viscosity electrolyte of claim 1, wherein the viscosity of the electrolyte is 5cp to 10cp at 25 ℃, 40cp to 60cp at 45 ℃, and the viscosity of the electrolyte increases by at least 100% at a potential above 4V.
5. An electrolyte microfluidic distribution system, wherein the system is configured to inject the self-regulating viscosity electrolyte of any one of claims 1-4 into the interior of a battery; the electrolyte microfluidic distribution system comprises: a distributed sensor array for monitoring local temperature and impedance inside the battery; The microfluidic actuator comprises a liquid storage tank, a micromixer and a piezoelectric microvalve, wherein the liquid storage tank, the micromixer and the piezoelectric microvalve are respectively used for storing basic electrolyte and self-adjusting viscosity additive concentrated liquid; and the control unit is used for calculating the viscosity of the electrolyte required by the target area according to the local temperature and the impedance and controlling the opening degrees of the micro mixer and the piezoelectric micro valve.
6. The microfluidic distribution system according to claim 5, wherein the control unit has pre-stored therein an AI decision model constructed by establishing a four-dimensional map of electrolyte viscosity, temperature, current and ionic conductivity and setting a concentration polarization voltage threshold, the control unit being configured to output a control instruction to increase the proportion of self-adjusting viscosity additives when the calculated concentration polarization voltage exceeds the threshold, and/or, The micromixer is a Y-type micromixer, and/or, The microfluidic actuator conveys electrolyte through a micro-channel embedded in the battery, the width of the micro-channel is 100-300 mu m, and/or, The response time of the piezoelectric microvalve is less than 20ms, and/or, The impedance sensor in the distributed sensor array is a three-electrode impedance sensor comprising a lithium reference electrode for monitoring concentration polarization impedance at an electrode interface.
7. A method for adaptively controlling the viscosity of a quick-change battery based on the electrolyte microfluidic distribution system according to any one of claims 5 to 6, comprising: Collecting local temperature data and impedance data inside the battery; Inputting the local temperature data and the impedance data into a preset decision model, and calculating an optimal viscosity value required by a target area by taking the minimum concentration polarization as a target on the basis of the coupling relation of viscosity, temperature, current and conductivity by the decision model; calculating the mixing proportion of the basic electrolyte and the self-adjusting viscosity additive concentrated solution according to the optimal viscosity value; and adjusting the opening of a piezoelectric micro valve in the microfluidic actuator, mixing according to the mixing proportion, and injecting the mixture into a target area of the battery.
8. The method for adaptively controlling the viscosity of a quick-change battery according to claim 7, further comprising: when the temperature of the central area of the battery module is higher than the temperature of the edge area and the temperature difference exceeds a preset threshold value, the control unit controls the proportion of the self-regulating viscosity additive in the electrolyte injected into the central area to be higher than the proportion of the self-regulating viscosity additive injected into the edge area.
9. A lithium ion battery, characterized in that it is internally filled with a self-regulating viscosity electrolyte according to any one of claims 1-4 or integrated with an electrolyte microfluidic distribution system according to any one of claims 5-6.
10. An electrical device comprising the lithium-ion battery of claim 9.

Description

Self-adjusting viscosity electrolyte and microfluidic distribution system thereof Technical Field The invention relates to the technical field of lithium batteries, in particular to self-adjusting viscosity electrolyte and a microfluidic distribution system thereof. Background With the popularization of new energy automobiles and portable electronic devices, lithium ion batteries are used as core energy storage devices, and the energy density and the charging speed of the lithium ion batteries become key indexes for measuring the performance of products. In particular, in the field of electric automobiles, in order to alleviate mileage anxiety, realization of rapid charging (for example, 3C rate or more) has become an urgent need for industry development. The performance of lithium ion batteries, particularly the fast charge capacity and safety, is highly dependent on the nature of the electrolyte. The electrolyte is used as a carrier for ion transmission in the battery, and the mass transfer dynamics of the electrolyte directly influences the reaction rate of an electrode interface and the overall polarization level of the battery. Currently, in order to meet the use requirements of lithium ion batteries in different environments and working conditions, the prior art generally adopts a method for optimizing an electrolyte formula. Common means include adding functional additives to the base solvent or adjusting the solvent ratio. For example, to improve low temperature performance, low viscosity co-solvents (such as linear carboxylates) are typically added to reduce system viscosity and increase ionic conductivity, while to increase safety and stability at high temperatures, thickeners or film forming additives are added to inhibit side reactions and gassing. In addition, some battery systems employ external thermal management systems or simple additive replenishment systems that attempt to regulate the operating environment of the battery based on voltage or temperature thresholds. However, the existing electrolyte system has contradiction that is difficult to reconcile when dealing with the working conditions of high-rate quick charge and wide temperature range. On one hand, the migration rate of lithium ions in the electrolyte under the fast charge condition is often delayed from the electrode reaction rate, so that significant concentration polarization is caused, and lithium precipitation and capacity fading are easy to initiate. On the other hand, the viscosity requirements of the electrolyte are quite opposite at different temperatures and voltages, namely low-temperature needs to be low in viscosity to maintain ionic conduction, low-viscosity components are high in volatility and poor in high-temperature stability, safety risks are easily caused, high-temperature or high-voltage needs to be high in viscosity to inhibit side reactions, and conventional thickeners can cause rapid reduction of ion mobility at low temperature, so that performance water jump is caused. In addition, most of the existing electrolyte formulas are fixed 'static' formulas before delivery, and cannot cope with complex dynamic changes inside the battery. In summary, existing electrolyte technologies rely mainly on off-line parameter optimization or simple open loop feedforward control, lacking real-time response capability to microscopic state changes inside the battery. The electrolyte with fixed viscosity cannot achieve both low-temperature conduction and stability at high temperature/high voltage, and is difficult to adapt to local performance differences inside the battery due to uneven temperature distribution (such as center-to-edge temperature difference). The single and static electrolyte system is difficult to meet the comprehensive requirements of the modern lithium ion battery on safety, quick charge performance and cycle life under all working conditions, and becomes a bottleneck for limiting the battery performance to further break through. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide self-regulating viscosity electrolyte and a microfluidic distribution system thereof, wherein the self-regulating viscosity electrolyte utilizes the main guest action of a four-arm star-shaped block copolymer and cyclodextrin to realize double self-adaptive regulation of the viscosity of the electrolyte to temperature and potential while ensuring efficient ion conduction, so that the technical problem that the high-temperature high-pressure stability and quick-charge dynamic performance of a battery are difficult to be compatible is solved. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: in a first aspect, the present invention provides a self-regulating viscosity electrolyte comprising a base electrolyte, cyclodextrin, and a self-regulating viscosity additive; The self-regulating viscosity additiv