Electrolyte corrosion-resistant additives for secondary batteries with metal-containing current collectors and batteries

Abstract

The present application relates to a kind of electrolyte corrosion-resistant additives and battery for metal-containing current collector of secondary battery.The chemical structural formula of the electrolyte corrosion-resistant additive is A x B y Wherein A is cation, B is anion, x, y satisfy the matter electricity neutrality of chemical structural formula;Metal element of metal current collector becomes ion state cation M at high potential by losing electron c+ Wherein c is ion valence state, anion B of the electrolyte corrosion-resistant additive is combined with the ion state cation M c+ Form passivation layer on the surface of the metal current collector, to block the metal current collector from being corroded by the electrolyte of secondary battery.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to an electrolyte anti-corrosion additive and a battery for secondary batteries containing metal current collectors. Background Technology

[0002] Aqueous batteries are low-cost, safe, reliable, and environmentally friendly, naturally possessing a non-flammable safety advantage compared to commercially available organic electrolytes. Furthermore, the production conditions for aqueous batteries are far less demanding than those for organic batteries, allowing for fewer steps and lower costs in industrial production. With ongoing research, the emergence of new systems such as "water-in-salt" electrolytes has pushed the voltage window of aqueous electrolytes beyond 1.23V, providing new possibilities for the future development of energy storage and power batteries, thus giving aqueous batteries a broad development prospect.

[0003] However, aqueous batteries also face significant challenges. Corrosion is a major bottleneck hindering their development. Corrosion during battery operation contaminates and degrades the electrolyte, reduces coulombic efficiency, increases battery polarization, affects the insertion / extraction of active materials, and impairs the normal function of the current collector, thus severely reducing the lifespan of the aqueous battery. High-concentration aqueous electrolytes can mitigate corrosion, but to reduce the cost of aqueous batteries, future development will inevitably move towards low-concentration electrolytes. In this context, corrosion will become increasingly severe, making the suppression of current collector corrosion crucial for the development of aqueous batteries.

[0004] Even in less demanding organic environments, metals like aluminum still corrode, especially in high-voltage batteries. Considering cost and energy density, current collectors should ideally be made of low-density, inexpensive materials with good conductivity. While carbon-based current collectors don't suffer from corrosion, their poor conductivity, high cost, and weak mechanical properties have prevented their widespread commercial use in batteries.

[0005] Therefore, solving the corrosion problem of current collectors in batteries is particularly crucial. Summary of the Invention

[0006] This invention provides an electrolyte anti-corrosion additive and a battery for a secondary battery containing a metal current collector. The anti-corrosion additive combines with the ionic cations of the metal current collector to form a passivation layer on the surface of the metal current collector, thereby preventing further corrosion of the metal current collector by the secondary battery electrolyte.

[0007] In a first aspect, embodiments of the present invention provide an electrolyte corrosion-resistant additive for secondary batteries containing metal current collectors, wherein the chemical structural formula of the electrolyte corrosion-resistant additive is A. x B yWhere A is a cation, B is an anion, and x and y satisfy the chemical structural formula A x B y The substance is electrically neutral;

[0008] The metal element in a metal current collector loses electrons at high potential and becomes an ionic cation M. c+ Where c is the ionic valence state, and the anion B of the electrolyte anti-corrosion additive reacts with the ionic cation M. c+ A passivation layer is formed on the surface of the metal current collector to prevent the metal current collector from being corroded by the electrolyte of the secondary battery.

[0009] Preferably, the electrolyte includes an aqueous electrolyte, an organic electrolyte, or a mixed aqueous and organic electrolyte.

[0010] More preferably, the electrolyte is an aqueous electrolyte or a mixed aqueous and organic electrolyte, and the anion B is a hydrolyzable weak acid anion or a weak acid anion capable of multi-stage hydrolysis. The anion B and the cation M... c+ It undergoes double hydrolysis in water to form M(OH). c The electrochemical corrosion of the metal current collector releases the cation M. c+ The passivation layer is formed on the corrosion sites.

[0011] More preferably, the hydrolyzable weak acid anion includes: CO32- 2- SiO3 2- S 2- C2O4 2- F - ,ClO - SO3 2- CH3COO - or AlO2 - One or more of the following; the weak acid anions that can be hydrolyzed in multiple stages include: HCO3- - HSiO3 - HS - or HC2O4 - One or more of them.

[0012] More preferably, the electrolyte is an aqueous electrolyte or a mixed aqueous and organic electrolyte, wherein the anion B and the cation M c+ The compound M formed m B n No double hydrolysis occurs in water; the anion B or its ionization product reacts with the cation M of the metal current collector. c+ The passivation layer is formed by deposition on the surface of the metal current collector; m and n satisfy the chemical structural formula Mm B n The substance is electrically neutral.

[0013] More preferably, the electrolyte is an organic electrolyte, and the anion B and cation M c+ The compound M formed m B n No double hydrolysis occurs in water; the anion B or its ionization product reacts with the cation M of the metal current collector. c+ The passivation layer is deposited on the surface of the metal current collector to form the passivation layer.

[0014] More preferably, the cation M is Al. 3+ Fe 3+ Ti 2+ or Cu 2+ One or more of the following, wherein the anion B is PO4. 3- HPO4 2- or H2PO4 - One or more of the following; or, the cation M is Fe 2+ Fe 3+ or Cu 2+ One or more of the following, wherein the anion B is S 2+ HS - One or more of the following.

[0015] Preferably, the metal current collector includes: a current collector formed of a metal material containing aluminum, nickel, iron, copper, titanium, or stainless steel, or a current collector formed of an alloy containing any of the metal materials, or a current collector formed by combining the metal material or alloy with a non-metallic material.

[0016] More preferably, the metal current collector further includes doped metal elements.

[0017] Secondly, embodiments of the present invention provide a secondary battery comprising the electrolyte anti-corrosion additive described in the first aspect.

[0018] The electrolyte corrosion-resistant additive provided by this invention for secondary batteries containing metal current collectors forms a passivation layer on the surface of the metal current collector by combining the anions of the electrolyte corrosion-resistant additive with the ionic cations of the metal current collector, thereby preventing further corrosion of the metal current collector by the secondary battery electrolyte. It has the advantages of being economical, practical and having good corrosion resistance. Attached Figure Description

[0019] The technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0020] Figure 1This is a schematic diagram illustrating the anti-corrosion principle of the water-based electrolyte anti-corrosion additive provided in this embodiment of the invention.

[0021] Figure 2 A comparison of Tafel curves before and after adding lithium carbonate, the anti-corrosion additive provided in this embodiment of the invention, to aluminum foil in 10m LiTFSI electrolyte;

[0022] Figure 3 Comparison of corrosion chronoamperometry experiments of aluminum foil before and after adding anti-corrosion additive Li2CO3 to 10m LiTFSI electrolyte;

[0023] Figure 4 The image is a scanning electron microscope (SEM) image of aluminum foil after a chronoamperometry corrosion experiment in 10 mL LiTFSI electrolyte.

[0024] Figure 5 SEM image of the working electrode aluminum foil after adding anti-corrosion additive Li2CO3 to 10m LiTFSI electrolyte and performing chronoamperometry experiment on the solution;

[0025] Figure 6 SEM image of the working electrode aluminum foil after adding anti-corrosion additive Li3PO4 to 10m LiTFSI electrolyte and performing chronoamperometry experiments on the solution;

[0026] Figure 7 SEM image of the working electrode aluminum foil after adding anti-corrosion additive Li2SiO3 to 10m LiTFSI electrolyte and performing chronoamperometry experiments on the solution;

[0027] Figure 8 SEM image of the working electrode aluminum foil after adding anti-corrosion additive LiAlO2 to 10m LiTFSI electrolyte and performing chronoamperometry experiments on the solution;

[0028] Figure 9 The results of inductively coupled plasma atomic emission spectrometry (ICP) analysis were obtained after chronoamperometry tests were conducted in 10 mL LiTFSI electrolyte and electrolytes with various anti-corrosion additives.

[0029] Figure 10 X-ray photoelectron spectroscopy (XPS) spectra of each aluminum foil after chronoamperometry tests were conducted on the original aluminum foil, in 10m LiTFSI electrolyte, and in electrolyte with various anti-corrosion additives.

[0030] Figure 11 A pH comparison of LiTFSI solutions at different concentrations and solutions to which saturated lithium carbonate anti-corrosion additives were added;

[0031] Figure 12 pH comparison of 1m LiTFSI and 10m LiTFSI solutions after adding various anti-corrosion additives;

[0032] Figure 13 Comparison of corrosion chronoamperometry experiments on aluminum foil before and after the addition of various anti-corrosion additives in 1m LiTFSI electrolyte;

[0033] Figure 14 ICP test results of aluminum content in each electrolyte after chronoamperometry experiments were conducted on 1m LiTFSI aluminum foil and solutions with various anti-corrosion additives.

[0034] Figure 15 The graph shows a comparison of the corrosion chronocurrent of aluminum foil in 1m NaTFSI electrolyte and after the addition of anti-corrosion additives Na2CO3 and Li2CO3, respectively.

[0035] Figure 16 SEM images of aluminum foil after a chronoamperometry corrosion experiment in 1m NaTFSI electrolyte;

[0036] Figure 17 SEM images of aluminum foil after corrosion chronoamperometry experiments were conducted in 1m NaTFSI electrolyte with the addition of anti-corrosion additive Na2CO3.

[0037] Figure 18 SEM images of aluminum foil after corrosion chronoamperometry experiments were conducted in 1m NaTFSI electrolyte with the addition of anti-corrosion additive Li2CO3.

[0038] Figure 19 The graph shows a comparison of ICP test results for aluminum foil in 1m NaTFSI electrolyte and after the addition of anti-corrosion additives Na2CO3 and Li2CO3, respectively, regarding the aluminum content in the electrolyte.

[0039] Figure 20 A comparison of the cycle specific capacity and coulombic efficiency of aqueous secondary lithium-ion batteries Li2MnO4-TiO2 in 10mLiTFSI electrolyte and in electrolyte with added lithium carbonate additive. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any way, that is, not intended to limit the scope of protection of the present invention.

[0041] The present invention proposes an anti-corrosion additive for electrolytes in secondary batteries containing metal current collectors, which can be applied to aqueous electrolytes, organic electrolytes, or mixed aqueous and organic electrolyte systems.

[0042] The chemical structural formula of the electrolyte corrosion inhibitor is A. x B y Where A is a cation, B is an anion, and x and y satisfy the chemical structural formula A x B y The substance is electrically neutral;

[0043] The metal element in a metal current collector loses electrons at high potential and becomes an ionic cation M. c+ Where c is the ionic valence state, and the anion B of the electrolyte anti-corrosion additive reacts with the ionic cation M. c+ A passivation layer is formed on the surface of the metal current collector to prevent the metal current collector from being corroded by the electrolyte of the secondary battery.

[0044] Forming a passivation layer to prevent the metal current collector from being corroded by the electrolyte of the secondary battery can include the following situations:

[0045] First, the electrolyte is an aqueous electrolyte or a mixed aqueous and organic electrolyte, and the anion B is a hydrolyzable weak acid anion or a weak acid anion capable of multiple hydrolysis stages. The anion B and the cation M... c+ It undergoes double hydrolysis in water to form M(OH). c And the electrochemical corrosion that occurs on the metal current collector releases the cation M. c+ The passivation layer is formed on the corrosion sites.

[0046] The weak acid anions obtained from the above hydrolysis include: CO32- 2- SiO3 2- S 2- C2O4 2- F - ,ClO - SO3 2- CH3COO - or AlO2 - One or more of the following; weak acid anions capable of multi-stage hydrolysis include: HCO3- - HSiO3 - HS - or HC2O4 - One or more of them.

[0047] Second, the electrolyte is an aqueous electrolyte or a mixed aqueous and organic electrolyte, with anions B and cations M. c+ The compound M formed m Bn No double hydrolysis occurs in water; the anion B or its ionization product reacts with the cation M of the metal current collector. c+ A passivation layer is formed by deposition on the surface of the metal current collector; m and n satisfy the chemical structural formula M m B n The substance is electrically neutral.

[0048] Third, the electrolyte is an organic electrolyte, containing anions B and cations M. c+ The compound M formed m B n No double hydrolysis occurs in water; the anion B or its ionization product reacts with the cation M of the metal current collector. c+ The passivation layer is formed by deposition on the surface of the metal current collector; m and n satisfy the chemical structural formula M m B n The substance is electrically neutral.

[0049] In the second and third cases described above, preferably, the cation M is Al. 3+ Fe 3+ Ti 2+ or Cu 2+ One or more of them, where the anion B is PO4. 3- HPO4 2- or H2PO4 - One or more of the following. Or preferably, the cation M is Fe. 2+ Fe 3+ or Cu 2+ One or more of them, where the anion B is S 2+ or HS - One or more of the following. Of course, there are other combinations, which will not be listed here.

[0050] The above three situations can be summarized as follows: the anti-corrosion additive of the present invention can be used to combine with metal ions generated during the corrosion of metal current collectors to directly form a precipitate, or to form a precipitate through double hydrolysis, covering the corrosion sites to play an anti-corrosion role, and preventing further corrosion through the passivation layer formed by the precipitate.

[0051] The metal current collector for secondary batteries using the anti-corrosion additive of this invention may include: a current collector formed from one of the following metal materials: aluminum, nickel, iron, copper, titanium, and stainless steel; or a current collector formed from an alloy of any of these metal materials; or a current collector formed from a composite of the metal material or alloy and a non-metallic material, wherein the non-metallic material may be such as carbon, a high-molecular-weight organic compound, etc. Furthermore, the metal current collector may also include other doped metal elements.

[0052] To better understand this invention, we will first explain the role of the anti-corrosion additive, combining its schematic diagram and chemical reaction equation.

[0053] Figure 1 This diagram illustrates the working principle of the anti-corrosion additives provided in this invention. HTAA is a hydrolyzable anionic additive, and PTAA is a precipitated anionic additive. Taking the most commonly used aluminum current collector as an example, under normal conditions, the aluminum current collector corrodes into aluminum ions under the influence of a high positive potential. These ions combine with electrolyte anions in the solution and diffuse into the solution, forming cavities at the original corrosion sites, leaving corrosion pits. After adding an anti-corrosion additive, such as lithium carbonate, the carbonate ions preferentially combine with the aluminum ions produced by corrosion and then immediately hydrolyze to form aluminum hydroxide. The aluminum hydroxide acts as a passivation layer, covering the original corrosion sites and thus preventing further corrosion of the aluminum. This diagram only shows the mechanism of lithium carbonate as an example; the working mechanisms of other available additives can be understood according to the following chemical reaction equations.

[0054] Corrosion mechanism of aluminum current collectors in commonly used aqueous LiTFSI electrolytes or aqueous-organic mixed systems:

[0055]

[0056] Al(s)-3e - →Al 3+ (aq) (Formula 2)

[0057] The corrosion resistance mechanism after adding corrosion-resistant additives such as Li2CO3:

[0058] Al(s)-3e - +3CO3 2- (aq) + 3H₂O → Al(OH)₃(s) + 3HCO₃ - (aq) (Formula 3)

[0059] Al(s)-3e - +3SiO3 2- (aq) + 3H₂O → Al(OH)₃(s) + 3HSiO₃ - (aq) (Formula 4)

[0060] Al(s)-3e - +3AlO2 - (aq)+6H2O→4Al(OH)3(s) (Formula 5)

[0061] Al(s)-3e - +PO4 3- (aq)→AlPO4(s) (Formula 6)

[0062] The mechanism in Equation 6 above also applies to organic electrolyte systems.

[0063] In other words, without the addition of anti-corrosion additives, aluminum loses electrons and becomes ionic at high potential, reacting with TFSI. - The aluminum ions combine and diffuse into the solution in ionic form, eventually leaving corrosion pits at the original sites. However, after adding corrosion-resistant additives (such as lithium carbonate, lithium silicate, and lithium aluminate), the slightly soluble carbonate ions in the solution preferentially combine with aluminum ions and rapidly undergo bidirectional hydrolysis to form aluminum hydroxide precipitate. This precipitate covers the corrosion sites, forming a passivation layer that hinders further corrosion of the aluminum current collector (Equations 3-5). The corrosion-resistant additive ions (such as PO42-) 3- The same effect can also be achieved by directly combining with aluminum ions to form a precipitate (Equation 6).

[0064] In one specific implementation, the electrolyte with the anti-corrosion additive of this invention can be obtained by adding lithium carbonate to an aqueous electrolyte until saturation, and then taking the supernatant. Those skilled in the art will know how to prepare an electrolyte with the anti-corrosion additive, and the preparation method will not be described further here.

[0065] The electrolyte with the anti-corrosion additive of this invention has a moderate pH in the range of 4-12, and there is no situation where excessive acidity or alkalinity affects hydrolysis or dissolution of the passivation layer.

[0066] The following examples will be used for comparison and illustration.

[0067] First, saturated lithium carbonate, saturated lithium phosphate, saturated lithium silicate, and saturated lithium alumina electrolytes were added to 10 mL LiTFSI (for comparison) and 10 mL LiTFSI, respectively. The following comparisons were made using Tafel curves, corrosion chronoamperometry experiments, inductively coupled plasma atomic emission spectrometry (ICP) tests, XPS spectra, and solution pH values.

[0068] Tafel test: Tafel curves were tested using a three-electrode method with a scan rate of 0.01 V / s. The working electrode was an aluminum foil, the counter electrode was an aluminum foil, and the reference electrode was an Ag / AgCl electrode. The electrolytes used were 10 m LiTFSI (for comparison) and 10 m LiTFSI with added saturated lithium carbonate. Figure 2 This is a comparison of Tafel curves of aluminum foil before and after adding the anti-corrosion additive lithium carbonate provided in this embodiment of the invention to 10 mL LiTFSI electrolyte. Figure 2It can be seen that the electrolyte with added corrosion inhibitors is more aluminum-friendly, with a corrosion potential of -1.365V, which is higher than the original electrolyte (-1.398V) without the added lithium carbonate corrosion inhibitors. The corrosion current density is 1.246 × 10⁻⁶. -6 A / cm 2 Compared to the original electrolyte without anti-corrosion additives, it has a viscosity of 7.51 × 10⁻⁶. -6 A / cm 2 It needs to be low. It needs to be clarified that... Figure 2 In the accompanying figures and subsequent figures, the concentration of the electrolyte used is expressed as molality, abbreviated as m, in accordance with industry practice.

[0069] Chronoamperometry Experiment: The chronoamperometry experiment used a three-electrode test. The working electrode was an aluminum foil, the counter electrode was an aluminum foil, and the reference electrode was an Ag / AgCl electrode. The electrolytes were 10 mL LiTFSI and 10 mL LiTFSI with saturated lithium carbonate, saturated lithium phosphate, saturated lithium silicate, and saturated lithium alumina electrolytes, respectively. The experiment lasted for 2 hours, maintaining a high potential of 4.5 V vs Li / Li. + For 10 minutes, the open-circuit voltage is maintained for 1 minute, and this cycle is repeated 12 times. Figure 3 This is a comparison graph of the corrosion chronoamperometry of aluminum foil before and after adding the corrosion inhibitor Li₂CO₃ to 10 mL LiTFSI electrolyte; the vertical axis represents the corrosion current density (A / cm²). 2 The horizontal axis represents time (s). According to... Figure 3 The results clearly show that the current density in the electrolyte with the various anti-corrosion additives added decreased significantly, by orders of magnitude. This indicates that after adding the anti-corrosion additives at high potential, no significant corrosion reaction occurred on the aluminum surface, and the durability of the current collector was greatly improved.

[0070] Figure 4 The image is a scanning electron microscope (SEM) image of aluminum foil after a chronoamperometry corrosion experiment in 10 mL LiTFSI electrolyte. Figure 5 SEM image of the working electrode aluminum foil after adding anti-corrosion additive Li2CO3 to 10m LiTFSI electrolyte and performing chronoamperometry experiment on the solution; Figure 6 SEM image of the working electrode aluminum foil after adding anti-corrosion additive Li3PO4 to 10mLiTFSI electrolyte and performing chronoamperometry experiment on the solution; Figure 7 This is a SEM image of the working electrode aluminum foil after a chronoamperometry experiment was conducted in a 10 mL LiTFSI electrolyte solution with the addition of the anti-corrosion additive Li2SiO3. Figure 8This is a SEM image of the working electrode aluminum foil after a chronoamperometry experiment was conducted in a 10 mL LiTFSI electrolyte solution with the addition of the corrosion-resistant additive lithium alumina (LiAlO2). Figure 4 It can be seen that the working electrode aluminum foil is significantly corroded, with very clear corrosion marks. However, after adding anti-corrosion additives, Figure 5 , 6 The aluminum foil in SEM images 7 and 8 is significantly more intact, with a substantial reduction and shallower corrosion pits. This indicates that the addition of the aforementioned anti-corrosion additives can effectively prevent further corrosion of the metal current collector.

[0071] After conducting chronoamperometry tests on the 10m LiTFSI electrolyte and the electrolyte with various anti-corrosion additives, the aluminum content in each electrolyte was measured using inductively coupled plasma emission spectrometry (ICP). The aluminum foil was 1cm thick. 2 The size and solution volume are both 10 mL. Figure 9 The results are shown below. The vertical axis represents the aluminum ion concentration (ppm) in the solution, and the horizontal axis represents the various electrolytes used in the experiment. It can be seen that under the condition of adding anti-corrosion additives, the aluminum content in the electrolyte after each corrosion experiment decreased, especially with the addition of anti-corrosion additives Li₂CO₃, Li₃PO₄, and LiAlO₂. This indicates that the anti-corrosion additives of this invention have a very good protective effect on aluminum, significantly reducing the dissolution of aluminum foil in LiTFSI solution at high potentials. The data obtained in the lithium carbonate experimental group in the actual test showed an even lower aluminum content than the blank sample from the machine; therefore, negative values ​​are discarded here, assuming that there are no aluminum ions in the solution, i.e., corrosion is completely inhibited.

[0072] Figure 10XPS spectra of the aluminum foil were obtained by scanning the original aluminum foil, the aluminum foil in 10 mL LiTFSI electrolyte, and the aluminum foil in electrolyte with added corrosion inhibitors after chronoamperometry tests. XPS spectra of the aluminum foil were also obtained after subsequent 60-second argon ion etching in the XPS testing system (the same etching procedure was performed on the original aluminum foil and the aluminum foil after chronoamperometry tests in 10 mL LiTFSI electrolyte and the aluminum foil in electrolyte with added corrosion inhibitors). It can be seen that a passivation layer forms on the surface of the aluminum foil during chronoamperometry tests in 10 mL LiTFSI electrolyte with added corrosion inhibitors. Specifically, in the experimental groups with lithium carbonate and lithium silicate additives, the aluminum hydroxide passivation layer peak around 74.2 was clearly visible; in the experimental group with lithium phosphate additives, the signal of the aluminum phosphate passivation layer around 74.4 could be found; the original aluminum foil showed obvious double peaks of aluminum metal at 2p1 / 2 and 2p3 / 2 on the right side, while the working electrode aluminum foil taken from the solution did not show double peaks of aluminum metal due to the presence of residual solvent components and passivation layer on the surface. After etching, the peak position of aluminum oxide changed due to the altered thickness of the aluminum oxide on the aluminum. However, the aluminum foil subjected to chronoamperometry experiments in a 10m LiTFSI solution containing lithium carbonate and lithium silicate still exhibited a significant aluminum hydroxide peak, with no change in peak position. Furthermore, the peak position of metallic aluminum was not eliminated. After adding anti-corrosion additives, a relatively thick passivation layer formed on the aluminum foil surface at high potential. A 60s etching time was insufficient to destroy this passivation layer, which is mainly composed of aluminum hydroxide. Simultaneously, the peak intensity of aluminum oxide significantly increased, indicating that the passivation layer was located outside the aluminum oxide layer. The peak intensity of aluminum oxide only increased after the passivation layer was consumed by etching. After 60s of etching in the 10m LiTFSI, the aluminum foil subjected to chronoamperometry experiments showed a distinct aluminum double peak, indicating that an effective passivation layer was not formed. Similarly, the lithium phosphate experimental group exhibited similar results; the aluminum phosphate passivation layer effectively covered the aluminum surface, and etching did not penetrate this protective layer.

[0073] Figure 11 A pH comparison of LiTFSI solutions at different concentrations and solutions to which saturated lithium carbonate anti-corrosion additives were added; Figure 12 A pH comparison was performed on 1 mL and 10 mL LiTFSI solutions after adding various anti-corrosion additives. Test conditions: pH was measured at 25°C using a pH meter. The results show a relatively uniform pH distribution, all within the range of 4-12, with no excessively acidic or alkaline conditions, indicating that the passivation layer can naturally and stably exist in these electrolytes.

[0074] Next, we added anti-corrosion additives to the low-concentration electrolyte and conducted corrosion chronoamperometry and ICP tests.

[0075] The electrolytes were 1 m LiTFSI (for comparison) and 1 m LiTFSI with added saturated lithium carbonate, saturated lithium phosphate, saturated lithium silicate, and saturated lithium alumina.

[0076] Comparative results of chronoamperometry experiments under low-concentration electrolytes are as follows: Figure 13 As shown. The vertical axis represents the corrosion current density (A / cm²). 2 The horizontal axis represents time (s). Test parameters: The chronoamperometry experiment used a three-electrode test. The working electrode was an aluminum foil, the counter electrode was an aluminum foil, and the reference electrode was an Ag / AgCl electrode. The electrolytes were 1 mL LiTFSI and 1 mL LiTFSI with various additives. The experiment lasted 2 hours, maintaining a high potential of 4.5 V vs Li / Li. + For 10 minutes, the open-circuit voltage is maintained for 1 minute, and this cycle is repeated 12 times. According to... Figure 13 The results clearly show that the current density decreased by 2-3 orders of magnitude in the electrolyte with the added corrosion inhibitor. This indicates that no significant corrosion reaction occurred on the aluminum surface after adding the corrosion inhibitor at high potential, greatly improving the durability of the current collector. It also demonstrates that the corrosion inhibitor remains effective in low-concentration alkaline electrolytes with a pH of around 10. This experiment shows that the aforementioned corrosion inhibitor still performs excellently in even lower-concentration electrolytes with more severe corrosive environments.

[0077] After conducting chronoamperometry tests on the 1m LiTFSI electrolyte and the electrolyte with various anti-corrosion additives, the aluminum content in each electrolyte was tested by ICP. The aluminum foil was 1cm thick. 2 The size and solution volume were both 10 mL, and the test results were as follows. Figure 14 As shown in the figure, it is clear that the aluminum ion content in the solution is significantly reduced when the anti-corrosion additive is added compared to when it is not added. The control group without the anti-corrosion additive has a very high aluminum content, proving that a considerable amount of aluminum is corroded and diffuses into the solution without the additive. This also demonstrates that the anti-corrosion additive of this invention has a very good protective effect on aluminum, greatly reducing the corrosion of aluminum foil in LiTFSI solution.

[0078] To further demonstrate the universality of the invention, a more prolonged and rigorous experimental verification was conducted on a scheme in which anti-corrosion additive Na2CO3 was added to 1m NaTFSI electrolyte.

[0079] Chronoamperometry test parameters: The chronoamperometry experiment used a three-electrode test. The working electrode was an aluminum foil, the counter electrode was an aluminum foil, and the reference electrode was an Ag / AgCl electrode. The electrolytes were 1 mM NaTFSI and 1 mM NaTFSI with saturated Li₂CO₃ and 0.05 mM Na₂CO₃ added respectively. The experiment lasted for 14 hours, maintaining a high potential of 4.5 V vs Li / Li + For 10 minutes, the open-circuit voltage is maintained for 1 minute, and this cycle is repeated.

[0080] The aluminum content in each electrolyte was then tested by ICP, with the aluminum foil being 1 cm thick. 2 The size and solution volume were both 10 mL, and the test results were as follows. Figure 15 As shown, the vertical axis represents the corrosion current density (A / cm²). 2 The horizontal axis represents time (s). According to... Figure 15 The results clearly show that, under conditions with the addition of the anti-corrosion additive, the current density is lower than that without the additive over time. This indicates that the addition of the anti-corrosion additive at high potential inhibits the corrosion reaction on the aluminum surface, significantly improving the durability of the current collector. In the experiment, the aluminum foil in 1 mL NaTFSI solution showed corrosion and breakage at the electrode-liquid interface. After adding Na₂CO₃, the aluminum foil in the solution showed a noticeable discoloration, but the corrosion was very weak. After adding Li₂CO₃, there was no significant change in the aluminum foil after the experiment. This demonstrates that the anti-corrosion additive of this invention provides excellent protection for aluminum, significantly reducing the corrosion of aluminum foil in NaTFSI solution.

[0081] Figure 16 SEM images of aluminum foil after a chronoamperometry corrosion experiment in 1m NaTFSI electrolyte; Figure 17 SEM images of aluminum foil after corrosion chronoamperometry experiments were conducted in 1m NaTFSI electrolyte with the addition of anti-corrosion additive Na2CO3. Figure 18 SEM images show the corrosion chronoamperometry results of aluminum foil after adding the corrosion inhibitor Li₂CO₃ to 1 mL NaTFSI electrolyte. It can be seen that in the 1 mL NaTFSI solution without the corrosion inhibitor, the aluminum foil exhibits severe, puncture-like corrosion pits. However, after adding the corrosion inhibitors Li₂CO₃ and Na₂CO₃, the number of corrosion pits on the surface is very small, and their depth is shallow. Although the aluminum foil shows yellowing to the naked eye after chronoamperometry in the solution with Na₂CO₃, no corrosion pits appear in the yellowed areas under electron microscopy, indicating a significant passivation effect.

[0082] This demonstrates that the anti-corrosion additive of the present invention has universal applicability.

[0083] Figure 19The graph shows a comparison of ICP test results for aluminum foil in 1 mL NaTFSI electrolyte and after the addition of anti-corrosion additives Na₂CO₃ and Li₂CO₃, respectively, regarding the aluminum content in the electrolyte. It can be seen that the addition of sodium carbonate and lithium carbonate significantly reduced the aluminum ion content in the solution after the corrosion experiment. This indicates that the anti-corrosion additives have a corrosion-mitigating and passivating effect in different aqueous electrolyte systems.

[0084] Example 1: The following provides a Li2MnO4-TiO2 aqueous secondary battery using an electrolyte corrosion-resistant additive. The specific fabrication process is as follows:

[0085] Positive electrode material and electrode manufacturing method:

[0086] The cathode material is LiMn2O4, which is purchased directly from the market.

[0087] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto aluminum foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0088] Negative electrode materials and electrode fabrication methods:

[0089] The negative electrode material is TiO2, which is purchased directly from the market.

[0090] Weigh out the negative electrode active material TiO2, conductive additive carbon black, and PVDF binder in a mass ratio of 8:1:1, where PVDF exists in the form of NMP solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto aluminum foil. After complete drying, use a slicing machine to obtain the electrode sheets. The mass ratio of positive to negative electrode is approximately 2:1.

[0091] Electrolyte system:

[0092] The electrolyte used is a 10 mL LiTFSI solution with water as the solvent and saturated lithium carbonate added. The supernatant is used to assemble the battery.

[0093] The battery assembly uses an aluminum-plastic film as the outer shell and a glass fiber separator. Constant current charge / discharge testing is conducted at a 3C rate, with charge / discharge voltages ranging from 0.7 to 2.5V.

[0094] Control group experimental conditions:

[0095] The experimental conditions were the same as above, except that the electrolyte was a 10 mL LiTFSI solution and no lithium carbonate additive was added.

[0096] Figure 20 This figure shows the cycle specific capacity and coulombic efficiency of the aqueous secondary lithium-ion battery Li2MnO4-TiO2 in this embodiment and the comparative example; the horizontal axis represents the number of cycles (N), the left vertical axis represents the charge / discharge specific capacity (mAh / g), and the right vertical axis represents the coulombic efficiency (%). Test parameters included constant current testing, voltage range (0.7-2.5V), and a charge / discharge rate of 3C. As can be seen from the figure, after 2000 cycles, the aqueous secondary battery using the anti-corrosion additive provided by this invention achieves a capacity retention rate of 89%, which is far superior to the control group battery without the anti-corrosion additive. The hydrolysis of the lithium carbonate additive forms an aluminum hydroxide passivation layer, which plays a crucial role.

[0097] Example 2: The following provides a Li2MnO4-TiO2 aqueous secondary battery using an electrolyte corrosion-resistant additive. The specific fabrication process is as follows:

[0098] Positive electrode material and electrode manufacturing method:

[0099] The cathode material is LiMn2O4, which is purchased directly from the market.

[0100] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto aluminum foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0101] Negative electrode materials and electrode fabrication methods:

[0102] The negative electrode material is TiO2, which is purchased directly from the market.

[0103] Weigh out the negative electrode active material TiO2, conductive additive carbon black, and PVDF binder in a mass ratio of 8:1:1, where PVDF exists in the form of NMP solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto aluminum foil. After complete drying, use a slicing machine to obtain the electrode sheets. The mass ratio of positive to negative electrode is approximately 2:1.

[0104] Electrolyte system:

[0105] The electrolyte used is a 10 mL LiTFSI solution with water as the solvent, and saturated lithium silicate is added. The supernatant is used to assemble the battery.

[0106] The battery assembly uses an aluminum-plastic film as the outer shell and a glass fiber separator. Constant current charge / discharge testing is conducted at a 3C rate, with charge / discharge voltages ranging from 0.7 to 2.5V.

[0107] Control group experimental conditions:

[0108] The experimental conditions were the same as above, except that the electrolyte was a 10m LiTFSI solution and no lithium silicate additive was added.

[0109] After adding lithium silicate additives, trace amounts of silicate and aluminum ions hydrolyze to form an aluminum hydroxide passivation layer, which inhibits the corrosion of the current collector in the battery, greatly improves the battery cycle life, and significantly improves the coulombic efficiency. This demonstrates the important role of anti-corrosion additives in inhibiting current collector dissolution and suppressing side reactions.

[0110] Example 3 provides a specific example of a Li2MnO4-TiO2 aqueous secondary battery using an electrolyte corrosion-resistant additive. The specific fabrication process is as follows:

[0111] Positive electrode material and electrode manufacturing method:

[0112] The cathode material is LiMn2O4, which is purchased directly from the market.

[0113] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto aluminum foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0114] Negative electrode materials and electrode fabrication methods:

[0115] The negative electrode material is TiO2, which is purchased directly from the market.

[0116] Weigh out the negative electrode active material TiO2, conductive additive carbon black, and PVDF binder in a mass ratio of 8:1:1, where PVDF exists in the form of NMP solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto aluminum foil. After complete drying, use a slicing machine to obtain the electrode sheets. The mass ratio of positive to negative electrode is approximately 2:1.

[0117] Electrolyte system:

[0118] The electrolyte used is a 10m LiTFSI solution with water as the solvent and saturated lithium aluminum oxide added. The supernatant is used to assemble the battery.

[0119] The battery assembly uses an aluminum-plastic film as the outer shell and a glass fiber separator. Constant current charge / discharge testing is conducted at a 3C rate, with charge / discharge voltages ranging from 0.7 to 2.5V.

[0120] Control group experimental conditions:

[0121] The experimental conditions were the same as above, except that the electrolyte was a 10m LiTFSI solution and no lithium alumina additive was added.

[0122] After adding lithium alumina additive, it hydrolyzes with aluminum ions to form aluminum hydroxide, which passivates the current collector of the battery, greatly reduces the battery capacity decay, and significantly improves the coulombic efficiency. This shows the important role of anti-corrosion additives in inhibiting current collector dissolution and suppressing side reactions.

[0123] Example 4 provides a specific example of a Li2MnO4-TiO2 aqueous secondary battery using an electrolyte corrosion-resistant additive. The specific fabrication process is as follows:

[0124] Positive electrode material and electrode manufacturing method:

[0125] The cathode material is LiMn2O4, which is purchased directly from the market.

[0126] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto aluminum foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0127] Negative electrode materials and electrode fabrication methods:

[0128] The negative electrode material is TiO2, which is purchased directly from the market.

[0129] Weigh out the negative electrode active material TiO2, conductive additive carbon black, and PVDF binder in a mass ratio of 8:1:1, where PVDF exists in the form of NMP solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto aluminum foil. After complete drying, use a slicing machine to obtain the electrode sheets. The mass ratio of positive to negative electrode is approximately 2:1.

[0130] Electrolyte system:

[0131] The electrolyte used is a 10 mL LiTFSI solution with water as the solvent and saturated lithium phosphate added. The supernatant is used to assemble the battery.

[0132] The battery assembly uses an aluminum-plastic film as the outer shell and a glass fiber separator. Constant current charge / discharge testing is conducted at a 3C rate, with charge / discharge voltages ranging from 0.7 to 2.5V.

[0133] Control group experimental conditions:

[0134] The experimental conditions were the same as above, except that the electrolyte was a 10m LiTFSI solution and no lithium phosphate additive was added.

[0135] After adding lithium phosphate additive, it directly precipitates with aluminum ions on the current collector surface to form an aluminum phosphate passivation layer, which inhibits current collector corrosion, greatly improves battery cycle life, and significantly enhances coulombic efficiency. This demonstrates the important role of anti-corrosion additives in suppressing current collector dissolution and side reactions. Without additives, the battery system using pure 10m LiTFSI electrolyte exhibits rapid capacity decay, resulting in a stark contrast in lifespan.

[0136] The above examples demonstrate the significant improvement that anti-corrosion additives for aqueous secondary batteries bring to the practical application of aluminum current collectors in harsh aqueous electrolyte environments. The following examples will use commonly used current collectors such as iron, copper, stainless steel, and titanium.

[0137] Example 5 below provides a specific example of a Li2MnO4-TiO2 aqueous secondary battery using an electrolyte corrosion-resistant additive. The specific fabrication process is as follows:

[0138] Positive electrode material and electrode manufacturing method:

[0139] The cathode material is LiMn2O4, which is purchased directly from the market.

[0140] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto iron foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0141] Negative electrode materials and electrode fabrication methods:

[0142] The negative electrode material is TiO2, which is purchased directly from the market.

[0143] Weigh out the negative electrode active material TiO2, conductive additive carbon black, and PVDF binder in a mass ratio of 8:1:1, where PVDF exists in the form of NMP solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto iron foil. After complete drying, use a slicing machine to obtain the electrode sheets. The mass ratio of positive to negative electrode is approximately 2:1.

[0144] Electrolyte system:

[0145] The electrolyte used is a 10 mL LiTFSI solution with water as the solvent and saturated lithium phosphate added. The supernatant is used to assemble the battery.

[0146] The battery assembly uses an aluminum-plastic film as the outer shell and a glass fiber separator. Constant current charge / discharge testing is conducted at a 3C rate, with charge / discharge voltages ranging from 0.7 to 2.5V.

[0147] Control group experimental conditions:

[0148] The experimental conditions were the same as above, except that the electrolyte was a 10m LiTFSI solution and no lithium phosphate additive was added.

[0149] After adding lithium phosphate additive, trace amounts of phosphate and iron ions precipitate on the current collector surface, forming an iron phosphate passivation layer. This inhibits current collector corrosion, significantly improves battery cycle life, and noticeably enhances coulombic efficiency. This demonstrates the crucial role of anti-corrosion additives in suppressing current collector dissolution and side reactions. Without additives, the battery system using pure 10m LiTFSI electrolyte exhibits rapid capacity decay, resulting in a stark contrast in lifespan.

[0150] Example 6 provides a specific example of a Li2MnO4-TiO2 aqueous secondary battery using an electrolyte corrosion-resistant additive. The specific fabrication process is as follows:

[0151] Positive electrode material and electrode manufacturing method:

[0152] The cathode material is LiMn2O4, which is purchased directly from the market.

[0153] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto copper foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0154] Negative electrode materials and electrode fabrication methods:

[0155] The negative electrode material is TiO2, which is purchased directly from the market.

[0156] Weigh out the negative electrode active material TiO2, conductive additive carbon black, and PVDF binder in a mass ratio of 8:1:1, where PVDF exists in the form of NMP solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto copper foil. After complete drying, use a slicing machine to obtain the electrode sheets. The mass ratio of positive to negative electrode is approximately 2:1.

[0157] Electrolyte system:

[0158] The electrolyte used is a 10 mL LiTFSI solution with water as the solvent and saturated lithium phosphate added. The supernatant is used to assemble the battery.

[0159] The battery assembly uses an aluminum-plastic film as the outer shell and a glass fiber separator. Constant current charge / discharge testing is conducted at a 3C rate, with charge / discharge voltages ranging from 0.7 to 2.5V.

[0160] Control group experimental conditions:

[0161] The experimental conditions were the same as above, except that the electrolyte was a 10m LiTFSI solution and no lithium phosphate additive was added.

[0162] After adding lithium phosphate additive, phosphate and copper ions directly precipitate on the current collector surface to form a copper phosphate passivation layer, which inhibits current collector corrosion, significantly improves battery cycle life, and noticeably enhances coulombic efficiency. This demonstrates the crucial role of anti-corrosion additives in suppressing current collector dissolution and side reactions. Without additives, the battery system using pure 10m LiTFSI electrolyte exhibits rapid capacity decay, resulting in a stark contrast in lifespan.

[0163] Example 7 provides a specific example of a Li2MnO4-TiO2 aqueous secondary battery using an electrolyte corrosion-resistant additive. The specific fabrication process is as follows:

[0164] Positive electrode material and electrode manufacturing method:

[0165] The cathode material is LiMn2O4, which is purchased directly from the market.

[0166] The positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder were weighed according to a mass ratio of 8:1:1, where PVDF existed in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, the PVDF was added, and the mixture was stirred at high speed and uniformly in a mixer. The slurry was then evenly coated onto titanium foil. After complete drying, the electrode sheets were obtained using a slicing machine.

[0167] Negative electrode materials and electrode fabrication methods:

[0168] The negative electrode material is TiO2, which is purchased directly from the market.

[0169] The negative electrode active material TiO2, conductive additive carbon black, and PVDF binder were weighed according to a mass ratio of 8:1:1, where PVDF existed in the form of NMP solution. After thoroughly grinding the active material and conductive additive, the PVDF was added, and the mixture was stirred at high speed and uniformly in a mixer. The slurry was then evenly coated onto titanium foil. After complete drying, the electrode sheets were obtained using a slicing machine. The mass ratio of positive to negative electrode was approximately 2:1.

[0170] Electrolyte system:

[0171] The electrolyte used is a 10 mL LiTFSI solution with water as the solvent and saturated lithium phosphate added. The supernatant is used to assemble the battery.

[0172] The battery assembly uses an aluminum-plastic film as the outer shell and a glass fiber separator. Constant current charge / discharge testing is conducted at a 3C rate, with charge / discharge voltages ranging from 0.7 to 2.5V.

[0173] Control group experimental conditions:

[0174] The experimental conditions were the same as above, except that the electrolyte was a 10m LiTFSI solution and no lithium phosphate additive was added.

[0175] After adding lithium phosphate additive, phosphate and titanium ions are directly deposited on the current collector surface to form a passivation layer, which inhibits the corrosion of the current collector in long-cycle batteries, improves the battery cycle life, and significantly improves the coulombic efficiency. The longer the cycle time, the more obvious the difference. Even though titanium is a very corrosion-resistant current collector, the intrinsic corrosion reaction still occurs slowly. Adding anti-corrosion additives extends the life of long-cycle batteries.

[0176] Example 8 provides a specific example of a Li2MnO4-TiO2 aqueous secondary battery using an electrolyte corrosion-resistant additive. The specific fabrication process is as follows:

[0177] Positive electrode material and electrode manufacturing method:

[0178] The cathode material is LiMn2O4, which is purchased directly from the market.

[0179] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto a stainless steel foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0180] Negative electrode materials and electrode fabrication methods:

[0181] The negative electrode material is TiO2, which is purchased directly from the market.

[0182] Weigh out the negative electrode active material TiO2, conductive additive carbon black, and PVDF binder in a mass ratio of 8:1:1, where PVDF exists in the form of NMP solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto stainless steel foil. After complete drying, use a slicing machine to obtain the electrode sheets. The mass ratio of positive to negative electrode is approximately 2:1.

[0183] Electrolyte system:

[0184] The electrolyte used is a 10 mL LiTFSI solution with water as the solvent and saturated lithium phosphate added. The supernatant is used to assemble the battery.

[0185] The battery assembly uses an aluminum-plastic film as the outer shell and a glass fiber separator. Constant current charge / discharge testing is conducted at a 3C rate, with charge / discharge voltages ranging from 0.7 to 2.5V.

[0186] Control group experimental conditions:

[0187] The experimental conditions were the same as above, except that the electrolyte was a 10m LiTFSI solution and no lithium phosphate additive was added.

[0188] After adding lithium phosphate additive, phosphate ions and metal ions generated by stainless steel corrosion form a passivation layer containing iron phosphate on the current collector surface, which inhibits current collector corrosion, greatly improves battery cycle life, and significantly improves coulombic efficiency. This demonstrates the important role of anti-corrosion additives in suppressing current collector dissolution and side reactions. Without additives, the battery system using pure 10m LiTFSI electrolyte experiences rapid capacity decay, resulting in a stark contrast in lifespan.

[0189] Example 9 provides a specific example of a Li2MnO4-TiO2 aqueous secondary battery using an electrolyte corrosion-resistant additive. The specific fabrication process is as follows:

[0190] Positive electrode material and electrode manufacturing method:

[0191] The cathode material is LiMn2O4, which is purchased directly from the market.

[0192] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto iron foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0193] Negative electrode materials and electrode fabrication methods:

[0194] The negative electrode material is TiO2, which is purchased directly from the market.

[0195] Weigh out the negative electrode active material TiO2, conductive additive carbon black, and PVDF binder in a mass ratio of 8:1:1, where PVDF exists in the form of NMP solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto iron foil. After complete drying, use a slicing machine to obtain the electrode sheets. The mass ratio of positive to negative electrode is approximately 2:1.

[0196] Electrolyte system:

[0197] The electrolyte used was a 10 mL LiTFSI solution with water as the solvent and 0.05 mL lithium sulfide added.

[0198] The battery assembly uses an aluminum-plastic film as the outer shell and a glass fiber separator. Constant current charge / discharge testing is conducted at a 3C rate, with charge / discharge voltages ranging from 0.7 to 2.5V.

[0199] Control group experimental conditions:

[0200] The experimental conditions were the same as above, except that the electrolyte was a 10m LiTFSI solution and no lithium sulfide additive was added.

[0201] After adding lithium sulfide additives, a passivation layer is formed on the current collector surface, which inhibits current collector corrosion, greatly improves battery cycle life, and significantly enhances coulombic efficiency. This demonstrates the important role of anti-corrosion additives in suppressing current collector dissolution and side reactions. Without additives, the battery system using pure 10m LiTFSI electrolyte exhibits rapid capacity decay, resulting in a stark contrast in lifespan.

[0202] Example 10 below provides a specific example of a Li2MnO4-TiO2 aqueous secondary battery using an electrolyte corrosion-resistant additive. The specific fabrication process is as follows:

[0203] Positive electrode material and electrode manufacturing method:

[0204] The cathode material is LiMn2O4, which is purchased directly from the market.

[0205] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto iron foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0206] Negative electrode materials and electrode fabrication methods:

[0207] The negative electrode material is TiO2, which is purchased directly from the market.

[0208] Weigh out the negative electrode active material TiO2, conductive additive carbon black, and PVDF binder in a mass ratio of 8:1:1, where PVDF exists in the form of NMP solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto iron foil. After complete drying, use a slicing machine to obtain the electrode sheets. The mass ratio of positive to negative electrode is approximately 2:1.

[0209] Electrolyte system:

[0210] The electrolyte used is a 10 mL LiTFSI solution with water as the solvent and saturated lithium carbonate added. The supernatant is used to assemble the battery.

[0211] The battery assembly uses an aluminum-plastic film as the outer shell and a glass fiber separator. Constant current charge / discharge testing is conducted at a 3C rate, with charge / discharge voltages ranging from 0.7 to 2.5V.

[0212] Control group experimental conditions:

[0213] The experimental conditions were the same as above, except that the electrolyte was a 10 mL LiTFSI solution and no lithium carbonate additive was added.

[0214] After adding lithium carbonate additive, trace amounts of carbonate and iron ions hydrolyze on the current collector surface to form an iron hydroxide passivation layer, which inhibits current collector corrosion, significantly improves battery cycle life, and noticeably enhances coulombic efficiency. This demonstrates the crucial role of anti-corrosion additives in suppressing current collector dissolution and side reactions. Without additives, the battery system using pure 10m LiTFSI electrolyte exhibits rapid capacity decay, resulting in a stark contrast in lifespan.

[0215] The present invention provides the application and performance of electrolyte anti-corrosion additives in aqueous electrolyte secondary batteries. The following examples illustrate the application of electrolyte anti-corrosion additives in organic electrolyte secondary batteries.

[0216] Example 11 provides a specific example of a LiCoO2-Li organic secondary battery using an electrolyte corrosion inhibitor, illustrating the application of electrolyte corrosion inhibitors in organic electrolyte secondary batteries.

[0217] The specific fabrication process of the LiCoO2-Li organic secondary battery is as follows:

[0218] Positive electrode material and electrode manufacturing method:

[0219] The cathode material is LiCoO2, which is purchased directly from the market.

[0220] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto aluminum foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0221] Negative electrode materials and electrode fabrication methods:

[0222] The negative electrode material is lithium foil purchased directly from the market.

[0223] Electrolyte system:

[0224] The electrolyte used was 1M LiTFSI, with a solvent of ethylene carbonate / dimethyl carbonate (EC / DMC) at a volume ratio of 1:1. Li3PO4 additive was added to the electrolyte until saturation, and the supernatant was used as the electrolyte. The concentration here is the molar concentration M (mol / L), which is different from the mass molar concentration m mentioned above.

[0225] The battery assembly uses a commercially available button cell casing, with a Celgard 2400 separator. Constant current charge / discharge testing was conducted at a rate of 0.5C, with charge / discharge voltages ranging from 2.5V to 4.3V.

[0226] Control group experimental conditions:

[0227] The experimental conditions were the same as above, except that the electrolyte was 1M LiTFSI, the solvent was EC / DMC with a volume ratio of 1:1, and no additives were added.

[0228] With the addition of lithium phosphate, the aluminum current collector is passivated during battery charging and discharging. Trace amounts of phosphate and aluminum ions directly precipitate to form an aluminum phosphate passivation layer, significantly improving cycle stability. Batteries without additives experience extremely rapid capacity decay, rendering them completely impractical. With the addition of lithium phosphate, the battery can cycle stably for many weeks, capacity decay is suppressed, and coulombic efficiency is significantly improved.

[0229] Example 12 provides a specific example of a LiCoO2-Li organic secondary battery using an electrolyte corrosion inhibitor, illustrating the application of electrolyte corrosion inhibitors in organic electrolyte secondary batteries.

[0230] The specific fabrication process of the LiCoO2-Li organic secondary battery is as follows:

[0231] Positive electrode material and electrode manufacturing method:

[0232] The cathode material is LiCoO2, which is purchased directly from the market.

[0233] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto iron foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0234] Negative electrode materials and electrode fabrication methods:

[0235] The negative electrode material is lithium foil purchased directly from the market.

[0236] Electrolyte system:

[0237] The electrolyte used was 1M LiTFSI, with a solvent of ethylene carbonate / dimethyl carbonate (EC / DMC) at a volume ratio of 1:1. Li3PO4 additive was added to the electrolyte until saturation, and the supernatant was used as the electrolyte. The concentration here is the molar concentration M (mol / L), which is different from the mass molar concentration m mentioned above.

[0238] The battery assembly uses a commercially available button cell casing, with a Celgard 2400 separator. Constant current charge / discharge testing was conducted at a rate of 0.5C, with charge / discharge voltages ranging from 2.5V to 4.3V.

[0239] Control group experimental conditions:

[0240] The experimental conditions were the same as above, except that the electrolyte was 1M LiTFSI, the solvent was EC / DMC with a volume ratio of 1:1, and no additives were added.

[0241] After adding lithium phosphate, the current collector is passivated during battery charging and discharging. Trace amounts of phosphate and iron ions directly precipitate to form an iron phosphate passivation layer, thus greatly improving cycle stability. Batteries without additives experience rapid capacity decay. With the addition of lithium phosphate, the battery can cycle stably for many weeks, capacity decay is suppressed, and coulombic efficiency is significantly improved.

[0242] Example 13 provides a specific example of a LiCoO2-Li organic secondary battery using an electrolyte corrosion inhibitor, illustrating the application of electrolyte corrosion inhibitors in organic electrolyte secondary batteries.

[0243] The specific fabrication process of the LiCoO2-Li organic secondary battery is as follows:

[0244] Positive electrode material and electrode manufacturing method:

[0245] The cathode material is LiCoO2, which is purchased directly from the market.

[0246] Weigh out the positive electrode active material LiMn2O4, conductive additive carbon black, and polyvinylidene fluoride (PVDF) binder in a mass ratio of 8:1:1, where PVDF exists in the form of N-methylpyrrolidone (NMP) solution. After thoroughly grinding the active material and conductive additive, add the PVDF and mix uniformly at high speed in a mixer. Then, evenly coat the slurry onto iron foil. After complete drying, use a slicing machine to obtain the electrode sheet.

[0247] Negative electrode materials and electrode fabrication methods:

[0248] The negative electrode material is lithium foil purchased directly from the market.

[0249] Electrolyte system:

[0250] The electrolyte used was 1M LiTFSI, with a solvent of ethylene carbonate / dimethyl carbonate (EC / DMC) at a volume ratio of 1:1. Lithium sulfide additive was added to the electrolyte until saturation, and the supernatant was used as the electrolyte. The concentration here is the molar concentration M (mol / L), which is different from the mass molar concentration m mentioned above.

[0251] The battery assembly uses a commercially available button cell casing, with a Celgard 2400 separator. Constant current charge / discharge testing was conducted at a rate of 0.5C, with charge / discharge voltages ranging from 2.5V to 4.3V.

[0252] Control group experimental conditions:

[0253] The experimental conditions were the same as above, except that the electrolyte was 1M LiTFSI, the solvent was EC / DMC with a volume ratio of 1:1, and no additives were added.

[0254] After adding lithium sulfide, the current collector is passivated during battery charging and discharging. Trace amounts of sulfur and iron ions directly precipitate to form an iron sulfide passivation layer, thereby greatly improving cycle stability. Batteries without additives experience rapid capacity decay. With the addition of lithium sulfide, the battery can cycle stably for many weeks, capacity decay is suppressed, and coulombic efficiency is significantly improved.

[0255] As can be seen from the above embodiments, the present invention has the following significant advantages:

[0256] 1. Economical and practical, only a small amount of anti-corrosion additive is needed to achieve anti-corrosion effect in the electrolyte.

[0257] 2. When current collectors made of metals such as aluminum corrode, aluminum ions preferentially combine with the anions of anti-corrosion additives, subsequently undergoing hydrolysis to form an aluminum hydroxide passivation layer covering the corrosion sites. Alternatively, the current collector metal ions and additive anions directly combine to form a passivation layer, such as AlPO4, allowing the aluminum current collector to operate in the battery for an extended period. This additive design concept, which uses the original corrosion products to form a passivation layer in the form of precipitation to protect the current collector from further corrosion, can also be applied to organic electrolytes. In organic electrolyte systems, additive anions can directly combine with the metal ions produced by corrosion to form a passivation layer, thereby preventing further corrosion.

[0258] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An anti-corrosion additive for electrolytes in secondary batteries containing metal current collectors, characterized in that, The chemical structural formula of the electrolyte anti-corrosion additive is A. x B y Where A is a cation, B is an anion, and x and y satisfy the chemical structural formula A x B y The substance is electrically neutral; the electrolyte is an aqueous electrolyte. The metal element in a metal current collector loses electrons at high potential and becomes an ionic cation M. c+ Where c is the ionic valence state, and anion B is a hydrolyzable weak acid anion, wherein the anion B and cation M c+ It undergoes double hydrolysis in water to form M(OH). c The electrochemical corrosion of the metal current collector releases the cation M. c+ On the corrosion sites, a passivation layer is formed on the surface of the metal current collector to prevent the metal current collector from being corroded by the electrolyte of the secondary battery. The hydrolyzable weak acid anions include: CO32- 2- SiO3 2- S 2- or AlO2 - One or more of them.

2. The electrolyte anti-corrosion additive according to claim 1, characterized in that, The metal current collector includes: a current collector formed of a metal material containing aluminum, nickel, iron, copper, titanium, or stainless steel; a current collector formed of an alloy containing any of the metal materials; or a current collector formed by a composite of the metal material and a non-metal material.

3. The electrolyte anti-corrosion additive according to claim 2, characterized in that, The metal current collector also includes doped metal elements.

4. A secondary battery comprising the electrolyte anti-corrosion additive as described in any one of claims 1-3.

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