Method for enhancing durability of electrochemical device
By adding metal phthalocyanine compounds to the electrochemical device and forming transition metal phthalocyanine compounds with the positive electrode material, the problems of electrode structure destruction and negative electrode interface degradation are solved, and the durability of the electrochemical device and the durability of the stainless steel casing are improved.
Patent Information
- Application Number
- CN202510221870.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-03-07
- Filing Date
- 2025-02-27
- Publication Date
- 2025-09-09
AI Technical Summary
The metal components in electrochemical devices dissolve metal ions during the charge and discharge process, destroying the electrode surface structure and making it impossible to form a good positive electrode electrolyte interface. This leads to degradation of the negative electrode solid electrolyte interface and affects the durability of the electrochemical device.
Adding metal phthalocyanine compounds as electrolyte additives in electrochemical devices allows them to form transition metal phthalocyanine compounds with transition metals in the positive electrode material, generating a beneficial positive electrode electrolyte interface, preventing transition metal ions from passing through the isolation membrane to reach the negative electrode, and improving the durability of the electrochemical device.
By generating a beneficial cathode electrolyte interface in the electrochemical device, transition metal ions are prevented from affecting the solid electrolyte interface on the negative electrode surface, the durability of the electrochemical device is increased, and the stainless steel casing is protected from corrosion.
Smart Images
Figure CN120613451A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for enhancing the durability of an electrochemical device, and in particular to a method for enhancing the durability of an electrochemical device by using an additive. Background Art
[0002] Electrode materials containing metal components in electrochemical devices, especially those containing transition metal components, such as titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), aluminum (Al), and molybdenum (Mo), as well as device casings often made of metals such as stainless steel, release metal ions during the charge and discharge process due to contact with the electrolyte. This not only damages the electrode surface structure and prevents the formation of a good cathode electrolyte interface (CEI), but can also cause transition metal ions to pass through the separator to the negative electrode, leading to degradation of the solid electrolyte interface (SEI) on the negative electrode surface and a decline in the durability of the electrochemical device. Summary of the Invention
[0003] To address the problems in current electrochemical devices where metal ions dissolve from the electrolyte, damaging the electrode surface structure and preventing the formation of a good cathode electrolyte interface (CEI), and where transition metal ions may even pass through the separator to the negative electrode, leading to degradation of the solid electrolyte interface (SEI) on the negative electrode surface and consequently a decline in the durability of the electrochemical device, the present invention provides a method for enhancing the durability of an electrochemical device, comprising the following steps:
[0004] Step S1: Providing an electrochemical device, which comprises at least a positive electrode, a negative electrode, and a separator therebetween within an electrochemical device housing or outer packaging, and an electrolyte disposed between the positive electrode and the negative electrode; wherein the positive electrode comprises a positive electrode material containing a transition metal; the electrolyte comprises an electrolyte additive; and the positive electrode material and / or the electrolyte additive comprises a metal phthalocyanine compound; and
[0005] Step S2: charging and discharging the electrochemical device to allow the metal phthalocyanine compound and the transition metal in the positive electrode material to form a transition metal phthalocyanine compound.
[0006] Furthermore, the metal of the metal phthalocyanine compound enters the electrochemical device in the form of metal ions to perform charge and discharge cycles.
[0007] The positive electrode generates a beneficial positive electrode electrolyte interface.
[0008] The transition metal in the positive electrode material does not pass through the isolation membrane to reach the negative electrode during the charge and discharge process.
[0009] The transition metal in the positive electrode material includes titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu) or zinc (Zn).
[0010] The metal of the metal phthalocyanine compound includes lithium, sodium, potassium, magnesium, calcium, zinc, copper, iron or aluminum.
[0011] The metal phthalocyanine compound includes dilithium phthalocyanine, disodium phthalocyanine, dipotassium phthalocyanine, magnesium phthalocyanine, calcium phthalocyanine, zinc phthalocyanine, copper phthalocyanine, iron phthalocyanine or aluminum phthalocyanine.
[0012] The shell of the electrochemical cell comprises a stainless steel shell.
[0013] The positive electrode and / or the negative electrode comprises a current collector, which comprises copper foil, aluminum foil, nickel foil, titanium foil, gold foil or platinum foil.
[0014] Wherein, the electrolyte comprises an ether or ester electrolyte.
[0015] As can be seen from the above description, the present invention adds a metal phthalocyanine to the electrolyte of an electrochemical device. After charging and discharging the electrochemical device, the metal phthalocyanine is converted into a phthalocyanine compound containing a transition metal from the positive electrode material, and a beneficial positive electrode electrolyte interface is formed on the surface of the positive electrode material and / or the surface of the device. This prevents the transition metal ions from being liberated to the negative electrode and affecting the formation of a solid electrolyte interface on the negative electrode surface, thereby increasing the durability of the electrochemical device. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of the present invention and are not intended to limit the technical scope of the present invention. Unless otherwise apparent from the context or otherwise specified, the same reference numerals in the figures represent the same structure or operation. Among them:
[0017] Figure 1 A schematic diagram of the process steps of a method for enhancing the durability of an electrochemical device according to the present invention.
[0018] Figure 2 This is a schematic diagram of the conversion of the dilithium phthalocyanine into the phthalocyanine compound containing the transition metal of the positive electrode material in a preferred embodiment of the present invention.
[0019] Figure 3A 、 Figure 3B They are respectively the X-ray photoelectron spectroscopy (XPS) at the positive electrode (cathode) of the comparative example without adding dilithium phthalocyanine and the soft-pack battery of Example 1 of the present invention after 100 cycles of charge and discharge.
[0020] Figure 3C 、 Figure 3D They are respectively the X-ray photoelectron spectroscopy (XPS) at the negative electrode (anode) of the comparative example without adding dilithium phthalocyanine and the soft-pack battery of Example 1 of the present invention after 100 cycles of charge and discharge.
[0021] Figure 4A 、 Figure 4B The left side is a scanning electron microscope image (SEM) and the right side is an elemental analysis image (EDX) of the negative electrode (anode) after charge and discharge cycles for a comparative example without adding dilithium phthalocyanine and Example 1 of the present invention.
[0022] Figure 5A The scanning electron microscope (SEM) images of the aluminum cathode (Al Cathode) after charge and discharge cycles are shown in the comparative example without adding dilithium phthalocyanine and Example 1 of the present invention.
[0023] Figure 5B Elemental analysis (EDX) diagram of the aluminum positive electrode after charge and discharge cycles for the comparative example without adding dilithium phthalocyanine and Example 1 of the present invention.
[0024] Figure 6A The scanning electron microscope (SEM) images of the aluminum cathode (Al Cathode) after 100 charge-discharge cycles are shown in the comparative example without adding dilithium phthalocyanine and Example 1 of the present invention.
[0025] Figure 6B Elemental analysis (EDX) diagram of the aluminum positive electrode after charge and discharge cycles for the comparative example without adding dilithium phthalocyanine and Example 1 of the present invention.
[0026] Please refer to Figure 7 The voltage, current, and time performance of the comparative example without adding dilithium phthalocyanine and the embodiment of the present invention under different charging environments are shown.
[0027] Figure 8A 、 8B The scanning electron microscope (SEM) images of the aluminum cathode (Al Cathode) after 100 charge-discharge cycles are shown in the comparative example and the example of the present invention without adding dilithium phthalocyanine.
[0028] Figure 9 1 is a composition analysis diagram of the aluminum protective layer after charge and discharge cycles in a comparative example without adding dilithium phthalocyanine and an embodiment of the present invention.
[0029] Figure 10A 、 10B , 10C are the voltage-capacitance diagrams of the comparative example and embodiments 1 and 2 under different charge and discharge cycles.
[0030] Figure 11Graphs showing the discharge capacitance and coulombic efficiency of the comparative example and embodiments 1 and 2 at different charge and discharge cycles.
[0031] Explanation of symbols:
[0032] Steps S1 to S3 DETAILED DESCRIPTION
[0033] The present invention will be technically illustrated and described in detail below with several preferred embodiments. The accompanying drawings are merely some exemplary representations or embodiments of the present invention. For those skilled in the art to which the present invention belongs, the present invention can also be applied to other similar situations based on these drawings without making any further effort.
[0034] The terms "system", "device", "unit" and / or "module" used in the present invention below are a method for distinguishing different components, elements, parts, parts or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions. As shown in the present invention, unless the context clearly indicates an exception, the words "a", "an", "a" and / or "the" do not specifically refer to the singular, but may also include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of clearly identified steps and elements, and these steps and elements do not constitute an exclusive list, and the method or device may also include other steps or elements.
[0035] Flowcharts are used in this disclosure to illustrate the operations performed by systems according to embodiments of the present invention. It should be understood that the preceding and following operations do not necessarily need to be performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.
[0036] Please refer to Figure 1 , which is a schematic diagram of the process steps of a method for enhancing the durability of an electrochemical device according to the present invention, wherein the steps include:
[0037] Step S1: Providing an electrochemical device, which comprises at least a positive electrode, a negative electrode, and a separator therebetween within an electrochemical device housing or outer packaging, and an electrolyte disposed between the positive electrode and the negative electrode; wherein the positive electrode comprises a positive electrode material comprising a transition metal; the electrolyte comprises an electrolyte additive; the positive electrode material and / or the electrolyte additive comprises a phthalocyanine compound, such as a dihydrophthalocyanine compound or a metal phthalocyanine compound, in an amount ranging from 0.01 wt % to 99.99 wt %; and
[0038] Step S2: charging and discharging the electrochemical device to allow the phthalocyanine compound and the transition metal in the positive electrode material to form a transition metal phthalocyanine compound.
[0039] Step S3 (optional): If the phthalocyanine compound is the metal phthalocyanine compound, the metal of the metal phthalocyanine compound enters the electrochemical device in the form of metal ions to perform charge-discharge cycles.
[0040] The outer shell of the electrochemical cell comprises a stainless steel outer shell. The positive electrode and / or the negative electrode comprises a current collector comprising copper foil, aluminum foil, nickel foil, titanium foil, gold foil or platinum foil.
[0041] The transition metal in the transition metal-containing positive electrode material includes titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), or zinc (Zn). The metal in the metal phthalocyanine compound includes lithium, sodium, potassium, magnesium, calcium, zinc, copper, iron, or aluminum; and the metal phthalocyanine compound includes dilithium phthalocyanine, disodium phthalocyanine, dipotassium phthalocyanine, magnesium phthalocyanine, calcium phthalocyanine, zinc phthalocyanine, copper phthalocyanine, iron phthalocyanine, or aluminum phthalocyanine.
[0042] <Example>
[0043] In a preferred embodiment of the present invention, the electrochemical device is a pouch cell. The positive electrode material comprises a ternary positive electrode material (NMC811). The electrolyte comprises an ether or ester electrolyte, for example, 1.5M LiFSI, DME / TTE (2:3 v / v) in this embodiment. The electrolyte additive comprises dilithium phthalocyanine. This embodiment is merely an example of the materials used for the positive electrode, the negative electrode, and the electrolyte. The positive electrode, the negative electrode, and the electrolyte are any applicable negative electrode and electrolyte types of existing electrochemical metal or ion batteries, and are not limited thereto. Experimental verification has demonstrated that the effects claimed by the present invention are achieved.
[0044] In the aforementioned steps 2 and 3, the lithium phthalocyanine is converted into a phthalocyanine compound containing the transition metal (TM) of the positive electrode material, such as Figure 2 As shown, it contains an iron phthalocyanine compound, a manganese phthalocyanine compound, or a cobalt phthalocyanine compound. Simultaneously, lithium ions in the dilithium phthalocyanine are released into the electrochemical device to participate in the charge-discharge cycle, forming an additional lithium source. The dilithium phthalocyanine of the present invention has lithium ion conductivity, protecting the positive electrode material originally containing the transition metal to form a beneficial positive electrode electrolyte interface (CEI), preventing the transition metal from passing through the separator to the negative electrode, and resolving the degradation problem of the solid electrolyte interface (SEI) on the negative electrode surface, thereby improving the durability of the electrochemical device.
[0045] In addition to soft-pack batteries, the present invention can also be applied to electrochemical devices made of stainless steel casings. In addition to converting the dilithium phthalocyanine into a phthalocyanine compound containing the transition metal of the positive electrode material during the electrochemical reaction, the transition metal is further converted into the phthalocyanine compound of the transition metal, thereby further preventing the problem of transition metal erosion or corrosion inside the stainless steel casing. This can also improve the durability of electrochemical devices made of stainless steel casings.
[0046] <Validity Test>
[0047] Please refer to Table 1 below, which shows a comparative example without dilithium phthalocyanine, Example 1 of the present invention in which dilithium phthalocyanine was added to the electrolyte, and Example 2 in which dilithium phthalocyanine was added to the positive electrode material. The positive electrode material used was an MNC811 pouch cell, and the electrolyte used was 1.5M LiFSI and DME / TTE (2:3 v / v).
[0048] Table 1.
[0049]
[0050]
[0051] Please refer to Figure 3A 、 Figure 3B , which is the X-ray photoelectron spectroscopy (XPS) at the positive electrode (cathode) of the comparative example without adding dilithium phthalocyanine and the soft-pack battery of Example 1 of the present invention after 100 cycles of charge and discharge. Figure 3A 、 Figure 3B The nitrogen and carbon source analysis shows that the preferred embodiment of the present invention (in the upper half of the figure) shows nitrogen and carbon source signals from lithium phthalocyanine at the positive electrode, indicating that lithium phthalocyanine can indeed remain at the positive electrode of the battery after multiple charge and discharge cycles. In contrast, the comparative example (in the lower half of the figure) without lithium phthalocyanine shows only sulfur and fluorine source signals from the electrolyte LiFSI at the positive electrode.
[0052] Please refer to Figure 3C 、 Figure 3D , which is the X-ray photoelectron spectroscopy (XPS) of the negative electrode (anode, Anode) of the soft-pack battery of the comparative example without adding dilithium phthalocyanine and the aforementioned Example 1 of the present invention after 100 cycles of charge and discharge. Figure 3C 、 Figure 3D The transition metal element analysis shows that the negative electrode of the preferred embodiment of the present invention in the upper half of the figure does not have any transition metal signals, but the comparative example without the addition of dilithium phthalocyanine in the lower half of the figure has obvious transition metal nickel and aluminum signals, indicating that the dilithium phthalocyanine of the present invention is indeed converted into a phthalocyanine compound containing the transition metal of the positive electrode material, preventing the transition metal from passing through the isolation membrane to the negative electrode.
[0053] Please refer to Figure 4A 、 Figure 4B , which is a comparative example without adding dilithium phthalocyanine and Example 1 of the present invention, the left scanning electron microscope image (SEM) and the right elemental analysis image (EDX) of the negative electrode (anode) after charge and discharge cycles. Figure 4A The comparative example shows that the negative electrode has obvious elemental signals of the transition metal elements nickel, manganese, and cobalt from the positive electrode material, while the example of the present invention has very weak elemental signals of the transition metal elements nickel, manganese, and cobalt, indicating that the example of the present invention adding lithium phthalocyanine can indeed inhibit the effect of transition metals from the positive electrode shuttling to the negative electrode.
[0054] Please refer to Figure 5A , which are scanning electron microscope images (SEM) of the aluminum cathode (Al Cathode) after charge and discharge cycles in a comparative example without adding dilithium phthalocyanine and Example 1 of the present invention. Figure 5B The following are the elemental analysis diagrams (EDX) of the aluminum positive electrode after charge and discharge cycles, for the comparative example without adding dilithium phthalocyanine and Example 1 of the present invention. Figure 5A 、 5B It can be seen that the surface of the aluminum positive electrode of the embodiment of the present invention produces transition element phthalocyanine compound particles formed by the combination of dilithium phthalocyanine, while the surface of the aluminum positive electrode of the comparative example produces corrosion. Figure 5B This shows that the surface of the aluminum positive electrode of the embodiment of the present invention has nitrogen-carbon functional groups of the phthalocyanine compound, while the surface of the comparative example only has sulfides from the electrolyte.
[0055] Please refer to Figure 6A 、 6B , which is a scanning electron microscope (SEM) image of the aluminum cathode (Al Cathode) after 100 charge and discharge cycles in a comparative example without adding dilithium phthalocyanine and Example 1 of the present invention. Figure 6B The following are the elemental analysis diagrams (EDX) of the aluminum positive electrode after charge and discharge cycles, for the comparative example without adding dilithium phthalocyanine and Example 1 of the present invention. Figure 6A 、 6B It can be seen that the positive electrode electrolyte interface (CEI) of lithium nitride and nickel nitride is simultaneously generated on the surface of the aluminum positive electrode of the embodiment of the present invention, preventing the transition metal ions from being liberated to the negative electrode and affecting the formation of the solid electrolyte interface on the negative electrode surface, thereby increasing the durability of the electrochemical device.
[0056] Please refer to Figure 7 , which is the voltage, current and time performance of the comparative example without adding lithium phthalocyanine and the embodiment of the present invention under different charging environments. Figure 7It can be seen that when the comparative example and the embodiment are charged at a constant voltage of 4.3V for more than 20 hours, the embodiment of the present invention can maintain good current and voltage performance during discharge, but the comparative example's performance is significantly reduced.
[0057] Please refer to Figure 8A 、 8B Scanning electron micrographs (SEM) of the aluminum cathode (Al cathode) after 100 charge-discharge cycles show the formation of transition element phthalocyanine compound particles on the surface of the aluminum cathode of the example, resulting from the reaction between aluminum and phthalocyanine. This demonstrates that the example of the present invention, which adds dilithium phthalocyanine, can indeed inhibit the shuttling of transition metals from the positive electrode to the negative electrode.
[0058] Please refer to Figure 9 , which shows the composition analysis of the aluminum protective layer after charge-discharge cycles in the comparative example and the example of the present invention, without the addition of dilithium phthalocyanine. Figure 10 shows that only the transition element phthalocyanine compound formed on the surface of the aluminum positive electrode of the example of the present invention after the reaction between aluminum and phthalocyanine, while the comparative example did not produce any transition element phthalocyanine compound.
[0059] Please refer to Figure 10A 、 10B , 10C, which is the voltage-capacitance diagram of the comparative example and Examples 1 and 2 at different charge and discharge cycles. It can be seen from the figure that when charging and discharging to 15 cycles, Examples 1 and 2 of the present invention have better capacitance performance than the comparative example. Please refer to Figure 11 , which is a graph of discharge capacitance and coulomb efficiency at different charge and discharge cycles for the comparative example and embodiments 1 and 2, Figure 11 It can be seen that Examples 1 and 2 of the present invention have better electrical performance than the comparative example.
[0060] Please refer to the following Table 2, which corresponds to the above Figures 3A to 11 The electrical performance data of the comparative example and the embodiment of the present invention.
[0061] Table 2.
[0062]
[0063]
[0064] In addition, unless otherwise expressly stated herein, the order of the elements, components, and sequences, the use of alphanumeric characters, or other names described herein are not intended to limit the order of the processes and methods of the present invention. Although the above text discusses some currently useful embodiments of the invention through various examples, it should be understood that such details are for illustrative purposes only, and the present invention is not limited to the disclosed embodiments but also includes equivalent related variations and modifications thereof.
[0065] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required characteristics of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present invention are approximate values, in specific embodiments, the settings of such numerical values are as accurate as possible within the feasible range.
[0066] Finally, it should be understood that the embodiments described herein are intended only to illustrate the principles of the present invention. Other variations are also possible and fall within the scope of the present invention. Therefore, by way of example and not limitation, alternative configurations of the embodiments of the present invention may be considered consistent with the teachings of the present invention. Accordingly, the embodiments of the present invention are not limited to the embodiments explicitly described and illustrated herein.
Claims
1. A method for enhancing the durability of an electrochemical device, characterized in that: The steps include: Step S1: Providing an electrochemical device, which comprises at least a positive electrode, a negative electrode, and a separator therebetween within an electrochemical device housing or outer packaging, and an electrolyte disposed between the positive electrode and the negative electrode; wherein the electrolyte comprises an electrolyte additive; the positive electrode material and / or the electrolyte additive comprises a dihydrophthalocyanine compound and / or a metal phthalocyanine compound capable of chelating metal ions; and Step S2: charging and discharging the electrochemical device to allow the dihydrophthalocyanine compound and / or the metal phthalocyanine compound to form a transition metal phthalocyanine compound with the transition metal in the positive electrode material.
2. The method for enhancing the durability of an electrochemical device according to claim 1, wherein: The metal of the dihydrophthalocyanine compound and / or the metal phthalocyanine compound enters the electrochemical device in the form of metal ions to perform charge and discharge cycles.
3. The method for enhancing the durability of an electrochemical device according to claim 1, wherein: The cathode creates a beneficial cathode-electrolyte interface.
4. The method for enhancing the durability of an electrochemical device according to claim 1, wherein: The transition metal in the positive electrode material does not pass through the isolation film to reach the negative electrode during the charge and discharge process.
5. The method for enhancing the durability of an electrochemical device according to claim 1, 2, 3 or 4, wherein: The transition metal in the positive electrode material includes titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu) or zinc (Zn).
6. The method for enhancing the durability of an electrochemical device according to claim 1, 2, 3 or 4, wherein: The metal of the metal phthalocyanine compound comprises lithium, sodium, potassium, magnesium, calcium, zinc, copper, iron or aluminum.
7. The method for enhancing the durability of an electrochemical device according to claim 6, wherein: The metal phthalocyanine compound comprises dilithium phthalocyanine, disodium phthalocyanine, dipotassium phthalocyanine, magnesium phthalocyanine, calcium phthalocyanine, zinc phthalocyanine, copper phthalocyanine, iron phthalocyanine or aluminum phthalocyanine.
8. The method for enhancing the durability of an electrochemical device according to claim 1, 2, 3 or 4, wherein: The housing of the electrochemical cell comprises a stainless steel housing.
9. The method for enhancing the durability of an electrochemical device according to claim 1, 2, 3 or 4, wherein: The positive electrode and / or the negative electrode comprises a current collector comprising copper foil, aluminum foil, nickel foil, titanium foil, gold foil or platinum foil.
10. The method for enhancing the durability of an electrochemical device according to claim 1, 2, 3 or 4, wherein: The electrolyte includes an ether or ester electrolyte.