Aqueous iodine-based battery based on multi-electron transfer

Abstract

The main structure of a multi-electron transfer aqueous iodine-based battery includes a positive electrode, a negative electrode, a current collector, an electrolyte, and a separator. Both the positive and negative electrodes use porous carbon felt as the electrode material, and a polymer membrane as the membrane material. The electrolytes for both electrodes are stored within the porous carbon felt electrodes. Both the positive and negative electrolytes contain I₂. ‑ and Cd 2+ In an acidic mixed solution, during charging, the I at the positive electrode... ‑ The charge is applied to Cd(IO3)2, resulting in an electrochemical reaction involving six electron transfers; the negative electrode is Cd. 2+ The deposition is Cd metal; the discharge process is the reverse. Due to the use of high-concentration electrolyte and the characteristics of multi-electron transfer, the battery energy density calculated based on the volume of the positive electrode electrolyte can reach 1100 Wh / L. To improve the kinetics and reversibility of the multi-electron transfer process, other additives need to be added to the solution, thereby improving the electrochemical reversibility of the entire reaction. Therefore, the battery can achieve an energy density of 80 mA / cm². 2 It achieves an energy efficiency of over 77% at current densities and operates stably for over 500 cycles.

Description

Technical Field

[0001] This invention relates to the field of batteries, and in particular to the field of multi-electron transfer aqueous iodine-based batteries. Background Technology

[0002] The large-scale use of fossil fuels has caused environmental pollution and an energy crisis. Therefore, the development and utilization of renewable energy is key to solving these problems. The promotion of electric vehicles is an important means of addressing the fossil fuel crisis. However, currently, electric vehicles mainly use lithium-ion batteries. Although lithium-ion batteries have a high energy density (~300Wh / L), the use of organic electrolytes can lead to flammability and explosiveness. Aqueous batteries, due to their high safety and high power density, have promising application prospects. However, the energy density of aqueous batteries is generally low at present, making them difficult to use in the field of power batteries. The applicant has previously developed a multi-electron transfer aqueous iodine-based battery. Under a strongly acidic environment, the I in the electrolyte at the positive electrode... - I2 can be generated through an electrochemical reaction, and I2 can then be charged to IO3. - This achieves six-electron transfer, and because I - I₂ has high solubility, thus enabling a significant leap in battery energy density. However, it faces severe electrochemical polarization problems during multi-electron transfer; during charging, I₂ is converted to IO₃. - The electrochemical process requires a five-electron transfer and the participation of multiple H2O molecules in the reaction. The symmetrical I2 molecules are difficult for water molecules to attack their positive charge centers, resulting in significant polarization of the reaction. However, for the discharge process, IO3... - Its structure is stable and its volume is relatively large. It also exhibits significant polarization during discharge, and can only pass through IO3. - I in oxidizing solution - I2 is formed to achieve indirect discharge, therefore, the entire electrochemical reaction is severely polarized. Summary of the Invention

[0003] To address the above problems, the present invention is as follows:

[0004] An iodine-based secondary battery based on multi-electron transfer includes a positive electrolyte and a negative electrolyte, both of which contain Cd. 2+ and I - Strongly acidic aqueous solutions and Br - and / or Cl - Source: Additives.

[0005] I in the positive and negative electrolytes - The sources can be one or more of HI, KI, or CdI2, while Cd 2+One or both of CdI2 and CdSO4 can be used; while H2SO4 can be selected as the supporting electrolyte in the electrolyte to ensure a strongly acidic environment.

[0006] Cd in positive or negative electrode electrolyte 2+ The molar concentrations were 0.5–3 M; I - Molar concentration of 1–6 M; Cd 2+ and I - The molar ratio is 1:2 to 1:1, H + The molar concentration is 3–12 M, in which Cd 2+ and I - The preferred molar ratio is 1:2.

[0007] During charging, the positive electrode I - Generated IO3 - Can react with Cd in solution 2+ The formation of Cd(IO3)2 precipitate solves the problem caused by the oxidation state charging product IO3. - Battery self-discharge problem caused by penetration.

[0008] Additives are added to both the positive and negative electrode electrolytes to reduce polarization during the electrochemical process. These additives primarily aim to introduce Br₂. - and / or Cl - The Br - The source additive can be one or more of NaBr, KBr, or HBr; while for Cl... - The additive source is one or more of NaCl, KCl, or HCl; the concentration of the additive introduced is 1–3 M.

[0009] The specific compositions of the positive electrode electrolyte and the negative electrode electrolyte are as follows:

[0010] HI is used as the iodine-based active material, with a concentration of 1–6 M (preferably 6 M); HBr and / or HCl are used as additives, with a concentration of 1–3 M (preferably 3 M); the supporting electrolyte H2SO4 has a concentration of 1–3 M (preferably 1 M); the active material for Cd is Cd(SO4)2, with a concentration of 1–3 M (preferably 3 M).

[0011] Alternatively, HI can be used as the iodine-based active material, with a concentration of 1–6 M (preferably 6 M); the additive is one or more of NaBr, KBr, NaCl, and KCl, with a concentration of 1–3 M (preferably 3 M); then the supporting electrolyte H2SO4 has a concentration of 2–4 M (preferably 2 M); the active material for Cd is Cd(SO4)2, with a concentration of 1–3 M (preferably 3 M); or, CdI2 can be selected as the active material, with a concentration of 0.5–3 M (preferably 3 M); HBr and / or HCl can be used as additives, with a concentration of 1–3 M (preferably 3 M); then the supporting electrolyte H2SO4 has a concentration of 2–4 M (preferably 4 M).

[0012] Alternatively, CdI2 can be selected as the active material, with a concentration of 0.5–3 M (preferably 3 M); and one or more of NaBr, KBr, NaCl, and KCl can be selected as additives, with a concentration of 1–3 M (preferably 3 M); then the concentration of the supporting electrolyte H2SO4 needs to be maintained at 3–5 M (preferably 5 M).

[0013] Alternatively, NaI and / or KI can be selected as the active material, with a concentration of 1–6 M (preferably 6 M for NaI and / or KI); HBr and / or HCl can be selected as the additive, with a concentration of 1–3 M (preferably 3 M for the additive); the supporting electrolyte H2SO4 can be selected with a concentration of 2–4 M (preferably 4 M for H2SO4); the active material for Cd can be Cd(SO4)2 with a concentration of 1–3 M (preferably 3 M for CdSO4); or, NaI and / or KI is used as the active substance, with a concentration of 1–6 M (preferably 6 M for NaI and / or KI); at the same time, one or more of NaBr, KBr, NaCl, and KCl are selected as additives, with a concentration of 1–3 M (preferably 3 M for additives); the concentration of the supporting electrolyte H2SO4 needs to be maintained at 3–5 M (preferably 5 M for H2SO4), and the active substance of Cd is Cd(SO4)2, with a concentration of 1–3 M (preferably 3 M for CdSO4).

[0014] A battery consists of a positive electrode, a negative electrode, a membrane material, and an electrolyte; both the positive and negative electrode electrolytes contain Cd. 2+ and I - The electrolyte is a strongly acidic aqueous solution, and additives need to be introduced into the electrolyte to improve the kinetics and reversibility of the electrochemical reaction process; the membrane material of the battery is a polymer material, such as PES, PVC, PSF, or PE, one or more of Nafion, preferably Nafion resin.

[0015] A battery includes a single cell or a stack. The structure of a single cell includes a positive terminal plate, a positive current collector, a positive carbon felt electrode filled with positive electrolyte, a separator, a negative carbon felt electrode filled with negative electrolyte, a negative current collector, and a negative terminal plate stacked in sequence. A stack is composed of two or more single cell circuits connected in series and / or in parallel.

[0016] During battery charging, the I in the positive electrode electrolyte - After I2 is generated on the porous electrode, charging continues to generate interhalogen compounds of iodine, such as IBr / ICl. Further charging then eventually generates IO3. - And with Cd 2+ Formation of Cd(IO3)2; Cd in the negative electrode electrolyte 2+ It is reduced to metallic Cd. For the discharge process, the discharge process at the positive electrode is that Cd(IO3)2 is indirectly discharged through a chemical oxidation-electrochemical reaction, ultimately generating I2O. - The discharge reaction at the negative electrode is the formation of Cd from metallic Cd; 2+ .

[0017] The beneficial effects of this invention are as follows:

[0018] This invention introduces other halide ions (Br) into the electrolyte. - Or Cl - As an additive, it can significantly improve the electrochemical activity and reversibility of the electrolyte. By forming interhalogen compounds (IBr / ICl) between halogens with different electronegativity (I2 and Br2 or I2 and Cl2), it facilitates the attack of water molecules on positive charge centers, thereby reducing charging polarization. For example, introducing Cl into the solution... - Or Br - As an additive, I2 can react with Br2 or Cl2 to form interhalogen compounds, such as ICl or IBr, during electrochemical reactions. Compared to symmetrical I2 molecules, the positive charge of ICl or IBr is mainly concentrated on the iodine atom. Therefore, during charging, the oxygen atom of H2O is more likely to attack it, thus favoring IO3. - The generation of IO3 - Can be used with Cd 2+ To form Cd(IO3)2, thereby avoiding IO3 - Self-discharge caused by osmosis. Reduces the electrochemical polarization during charging. For the discharge process, IO3... - By using other halide ions such as Cl - / Br - Chemical oxidation generates Br2 / Cl2, which can then enable indirect discharge, such as Cl2 / Cl... - Or Br2 / Br - Halogens with higher electronegativity have higher electrode potentials, such as Br2 / Br- The electrode potential is approximately 1.08V, which is higher than that of I2 / IO3. - The electrode potential of iodine IO3 is lower than 1.19V, therefore... - It is easy to make Br - Oxidation to elemental bromine, with a relatively small potential difference between the two, effectively reduces the discharge polarization of the battery, thus significantly reducing the discharge polarization. This system achieves Ig in a strongly acidic medium. - The reversible six-electron transfer reaction achieves extremely high energy density by increasing the number of electrons transferred and combining it with a high-concentration electrolyte. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a multi-electron transfer aqueous iodine-based battery system.

[0020] Figure 2 The charge-discharge curves and cycle performance diagrams for the battery assembled in Example 1 are shown. The electrolyte composition is: 0.5 M CdI₂, 3 M H₂SO₄, and 1 M HBr. The battery's operating current density is 80 mA / cm². 2 The membrane material is Nafion 115. The battery can operate at 80 mA / cm². 2 The battery operates stably for over 500 cycles at a given current density, with an energy density exceeding 180 Wh / L and an energy efficiency exceeding 78%. The battery structure mainly includes: a positive terminal plate, a positive current collector, a positive electrode, a separator, a negative electrode, a negative current collector, and a negative terminal plate. The battery's testing conditions are: charging cutoff conditions are dual cutoffs of voltage and capacity; discharging cutoff condition is a voltage of 0.1V; and the battery's charging and discharging process is constant current charging and discharging.

[0021] Figure 3 The charge-discharge curves and cycle performance graphs of the battery assembled in Example 2 are shown. The electrolyte composition is: 1M CdI₂, 3M H₂SO₄, 2M HBr. The battery's operating current density is 80 mA / cm². 2 The membrane material is Nafion 115. The battery can operate at 80 mA / cm². 2 It can operate stably for more than 400 cycles at current densities, with an energy density of more than 350 Wh / L and an energy efficiency of more than 77%.

[0022] Figure 4 The charge-discharge curves and cycle performance diagrams for the battery assembled in Example 3 are shown. The electrolyte composition is: 2.5M CdI₂, 3M H₂SO₄, 3M HBr, and the membrane material is Nafion 115 membrane. The battery can operate at 40 mA / cm². 2 It achieves an energy density of over 1100 Wh / L and an energy efficiency of over 75%.

[0023] Figure 5 The charge-discharge curves and cycle performance diagrams for the battery assembled in Example 4 are shown. The electrolyte composition is: 3M HI, 1.5M CdSO4, 3M H2SO4, 3M HBr, and the membrane material is Nafion 115 membrane. The battery can operate at 80 mA / cm². 2 It achieves an energy density of over 490 Wh / L, an energy efficiency of over 76%, and can operate stably for over 120 cycles.

[0024] Figure 6 The charge-discharge curves for the battery assembled in Example 5 are shown. The electrolyte composition is: 1M CdI₂, 3M H₂SO₄, 2M NaBr, and the membrane material is Nafion 115 membrane. The battery can operate at 80 mA / cm². 2 It achieves an energy density of over 350 Wh / L and an energy efficiency of over 76%.

[0025] Figure 7 The image shows the performance of the battery assembled in Example 6. The electrolyte composition is: 1M CdI₂, 3M H₂SO₄, 2M NaCl, with Br₂ as an additive. - Replace with Cl - The membrane material is Nafion 115. The battery can operate at 80 mA / cm². 2 It achieves an energy density of over 340 Wh / L and an energy efficiency of over 76%.

[0026] Figure 8 The image shows the performance of the battery assembled in Example 7. The electrolyte composition is: 1M CdI₂, 3M H₂SO₄, 2M HCl, and the membrane material is Nafion 115 membrane. The battery can achieve an efficiency of 80 mA / cm². 2 It achieves an energy density exceeding 345 Wh / L and an energy efficiency exceeding 76%.

[0027] Figure 9 The image shows the performance of the battery assembled in Preferred Example 1. The electrolyte composition is: 6M HI + 3M HBr + 1M H2SO4 + 3M CdSO4, and the membrane material is Nafion 115 membrane. The battery can achieve an efficiency of 80 mA / cm². 2 It achieves an energy density exceeding 1050 Wh / L and an energy efficiency exceeding 74%.

[0028] Figure 10 The image shows the performance of the battery assembled in Example 2. The electrolyte composition is: 6M HI + 3M KCl + 2M H2SO4 + 3M CdSO4, and the membrane material is Nafion 115 membrane. The battery can achieve an efficiency of 80 mA / cm². 2It achieves an energy density exceeding 1020 Wh / L and an energy efficiency exceeding 75%.

[0029] Figure 11 The image shows the performance of the battery assembled in Example 3. The electrolyte composition is: 6M NaI + 3M HBr + 4M H2SO4 + 3M CdSO4, and the membrane material is Nafion 115 membrane. The battery can achieve an efficiency of 80 mA / cm². 2 It achieves an energy density exceeding 1060 Wh / L and an energy efficiency exceeding 74%.

[0030] Figure 12 The image shows the performance of the battery assembled in Example 4. The electrolyte composition is: 6M NaI + 3M NaBr + 5M H2SO4, 3M CdSO4, and the membrane material is Nafion 115 membrane. The battery can achieve an efficiency of 80 mA / cm². 2 It achieves an energy density exceeding 1045 Wh / L and an energy efficiency exceeding 76%.

[0031] Figure 13 The image shows the performance of the battery assembled in Example 5. The electrolyte composition is: 3M CdI₂ + 3M HBr + 4M H₂SO₄ + 3M CdSO₄. The membrane material is Nafion 115 membrane. The battery can achieve an efficiency of 80 mA / cm². 2 It achieves an energy density exceeding 1074 Wh / L and an energy efficiency exceeding 74%.

[0032] Figure 14 The image shows the performance of the battery assembled in Example 6. The electrolyte composition is: 3M CdI₂ + 3M HBr + 4M H₂SO₄ + 3M CdSO₄. The membrane material is Nafion 115. The battery can achieve an energy density exceeding 1022 Wh / L at 80 mA / cm², and an energy efficiency exceeding 74%.

[0033] Figure 15 The image shows the performance test results of the multi-electron transfer iodine-based battery assembled in Comparative Example 1. The electrolyte composition was: 0.5 M dI₂, 3 M H₂SO₄, and the battery's operating current density was 80 mA / cm². 2 The membrane material is Nafion 115. However, the battery exhibits significant polarization, resulting in an energy efficiency of only 57%. Furthermore, due to the polarization, the battery's energy density is low, at only 114 Wh / L.

[0034] Figure 16 The image shows the performance test results of the multi-electron transfer iodine-based battery assembled in Comparative Example 2. The electrolyte composition was 1M HI, 3M H2SO4, 1M CdSO4, and 0.1M HBr. The battery's operating current density was 80 mA / cm². 2The membrane material is Nafion 115. Due to the low concentration of HBr, the battery polarization is large, resulting in an energy efficiency of only 54% and limiting the battery's energy density to only 104 Wh / L.

[0035] Figure 17 The image shows the performance test results of the battery assembled in Comparative Example 3. The electrolyte composition is: 1M HI, 3M H₂SO₄, 1M HBr, 0.2M CdSO₄. The battery's operating current density is 80 mA / cm². 2 The membrane material is Nafion 115 membrane. Due to the presence of Cd in the solution... 2+ :I - =1:5, generating IO3 - Cannot be used with Cd 2+ Cd(IO3)2 precipitate forms, and cross-contamination of the electrolyte is severe. Therefore, the battery has a low coulombic efficiency, with an energy efficiency close to 60% and an energy density of only ~103 Wh / L.

[0036] Figure 18 The image shows the performance test results of the assembled battery for Comparative Example 4. The electrolyte composition was: 0.5M CdI₂, 1M HBr. The battery's operating current density was 80 mA / cm². 2 The membrane material is Nafion 115. Although HBr is added as an additive, the presence of H+ in the solution... + The concentration is low, therefore, this will affect IO3. - Br oxide - The chemical reaction rate ultimately affects the battery's energy efficiency. Test results show that the battery achieves an efficiency of 80 mA / cm². 2 Its energy efficiency is only 65%, and its energy density is less than 150Wh / L.

[0037] Figure 19 The image shows the performance test results of the assembled battery in Comparative Example 5. The electrolyte composition is: 0.5M CdI₂, 0.5M H₂SO₄, 1M HBr. The battery's operating current density is 80 mA / cm². 2 The membrane material was Nafion 115. Similar to Comparative Example 4, although HBr was added as an additive and a portion of H2SO4 was added as a supporting electrolyte, the acid concentration was still low. Therefore, IO3... - Br oxide - The reaction rate is still insufficient, therefore the polarization of the battery is still relatively large, and the battery efficiency is only 70%.

[0038] Figure 20The image shows the performance test results of the battery assembled in Comparative Example 6. The electrolyte composition is: 0.1M CdI₂, 3M H₂SO₄, 1M HBr. The battery's operating current density is 80 mA / cm². 2 The membrane material is Nafion 115. However, in this electrolyte system, due to the low concentration of CdI2, the generated IO3... - The amount is relatively small, therefore, it is difficult to react with Br during the discharge process. - A chemical reaction occurs, therefore, the battery's polarization remains relatively high. Test results show that at 80 mA / cm²... 2 Under these conditions, the battery's energy efficiency is only 64%.

[0039] Figure 21 The image shows the performance test results of the battery assembled in Comparative Example 7. The electrolyte composition is: 0.5M CdI₂, 3M H₂SO₄, 1M HBr. The battery's operating current density is 80 mA / cm². 2 The membrane material is a porous PE membrane. Compared to Nafion 115 membranes, the PE porous membrane has a weaker barrier function against positive electrode charging products, resulting in severe electrolyte permeation and a very low coulombic efficiency. Battery test results show that the battery's energy density is only 52%.

[0040] Figure 22 The image shows the performance test results of the battery assembled in Comparative Example 8. The electrolyte composition is: 1M HI, 3M H2SO4, 1M TiOSO4. The battery's operating current density is 80 mA / cm². 2 The membrane material is Nafion 115 membrane. Compared to Cd... 2+ / Cd negative electrode, Ti 3 + / Ti 4+ When electricity is used as the negative electrode of a battery, the battery performance is very low, mainly due to I. - IO3 generated by oxidation - With Ti 4+ The generated Ti(IO3)4 exhibits poor kinetics during discharge, resulting in a battery energy efficiency of only 32%. Detailed Implementation

[0041] Performance testing of a multi-electron transfer iodine-based aqueous battery, with a charging current density of 80 mA / cm². 2 The battery charging cutoff voltage is 2.4V, and the discharging cutoff voltage is 0.1V; the carbon felt on both the positive and negative electrodes is 1mm thick and has an area of ​​48cm². 2 The electrolyte volume on the positive electrode side is 5 mL, and on the negative electrode it is 15 mL. Both the positive and negative electrolytes are adsorbed inside the porous carbon felt. The battery requires a Nafion 115 membrane. The positive and negative electrolytes are the same.

[0042] Figures 2-5 Examples 1-4 show the charge-discharge curves and cycle performance tests of the battery under optimal conditions. As the electrolyte concentration increases, the battery's energy density rises from 180 Wh / L at 1M to 1000 Wh / L. Furthermore, by maintaining a constant capacity of four electrons during charge-discharge, the battery can stably operate for more than 500 cycles.

[0043] Compared to electrolytes with HBr as an additive, try replacing HBr in the solution with NaBr, HCl, or NaCl (corresponding to Examples 5-7). Figures 6-8 Both can achieve high electrochemical activity, mainly because they can form iodine halogen intermetallic compounds (IBr / ICl) during charging, thereby reducing charging polarization; while for the discharging process, IO3... - It can oxidize Br - / Cl - This enables indirect discharge and thus increases the battery's discharge voltage. Therefore, the electrolyte system with the above additives can also achieve an energy efficiency of >75%.

[0044] The concentration of the electrolyte is increased to 6M (the most preferred electrolyte composition, preferred examples 1-6, corresponding to...). Figures 9-14 The battery has an energy density exceeding 1000 Wh / L and an efficiency exceeding 74%. This indicates that the optimal electrolyte has a significant advantage in terms of energy density.

[0045] Compared to electrolyte systems with added additives, electrolytes with lower additive concentrations or no additives exhibit severe polarization, resulting in lower battery performance (Comparative Examples 1-3) and energy efficiency below 60%.

[0046] Reducing the concentration of H2SO4 in the solution also slightly decreases the battery performance, mainly due to the decrease in H2SO4 concentration and the reduction in IO3 in the electrolyte. - The oxidizing power of Br in the oxidizing solution is reduced. - The rate of decrease (Comparative Examples 4-5).

[0047] Decrease I in solution - With increasing Ig concentration, battery efficiency also decreases significantly, mainly due to the decrease in Ig concentration. - As the concentration decreases, the rate of chemical oxidation of the electrolyte during charging and discharging is limited, resulting in a battery energy efficiency of only about 64% (Comparative Example 6).

[0048] When the Nafion 115 membrane was replaced with a PE polyolefin porous membrane, the coulombic efficiency of the battery was very low due to severe cross-contamination of the electrolyte (Comparative Example 7).

[0049] Battery Cd 2+ / Cd negative electrode replaced with Ti 3+ / Ti 4+ I - IO3 generated by oxidation - With Ti 4+ The formation of Ti(IO4)4 results in low battery efficiency and low energy density due to the limitation of Ti(IO4)4 reduction kinetics.

[0050] Table 1: Examples of Iodine-based Multi-Electron Transfer Battery Systems

[0051]

[0052] Table 2: Preferred Examples of Iodine-Based Multi-Electron Transfer Battery Systems

[0053]

[0054] Table 3: Comparative Examples of Iodine-Based Multi-Electron Transfer Battery Systems

[0055]

Claims

1. An aqueous iodine-based battery based on multi-electron transfer, comprising a positive electrode electrolyte and a negative electrode electrolyte, characterized in that: Both the positive and negative electrolytes contain Cd. 2+ and I - Strongly acidic aqueous solutions and Br - and / or Cl - Source of additives, Cd in the positive or negative electrode electrolyte 2+ The molar concentrations were 0.5–3 M; I - Molar concentration of 1-6 M; Cd 2+ and I - The molar ratio is 1:2 to 1:1, H + The molar concentration is 3~12 M, and the Br - The source additives are one or more of NaBr, KBr, or HBr; while for Cl... - The additives are derived from one or more of NaCl, KCl, or HCl; the concentration of the additives is 1-3 M; the battery includes a positive electrode, a negative electrode, a membrane material, and an electrolyte; both the positive and negative electrode electrolytes contain Cd. 2+ and I - The electrolyte is a strongly acidic aqueous solution, and additives need to be introduced into the electrolyte to improve the kinetics and reversibility of the electrochemical reaction process; the membrane material of the battery is a polymer material, such as PES, PVC, PSF, or PE, or one or more of Nafion.

2. The battery according to claim 1, characterized in that: I in the positive electrolyte and the negative electrolyte - The source is one or more than two of HI, KI or CdI2, and Cd 2+ One or more than two of CdI2 or CdSO4 is used, and H2SO4 is selected as the supporting electrolyte in the electrolyte to ensure a strong acidic environment.

3. The battery according to claim 1 or 2, characterized in that, Cd 2+ and I - in a molar ratio of 1 :

2.

4. The battery according to claim 1 or 2, characterized in that: During charging, the positive electrode I - Generated IO3 - With Cd in solution 2+ The formation of Cd(IO3)2 precipitate solves the problem caused by the oxidation state charging product IO3. - Battery self-discharge problem caused by penetration.

5. The battery according to claim 1, characterized in that: The specific compositions of the positive and negative electrolytes are as follows: HI is used as the iodine-based active material at a concentration of 1–6 M; HBr and / or HCl are used as additives at a concentration of 1–3 M; the supporting electrolyte H2SO4 is used at a concentration of 1–3 M; and the active material for Cd is Cd(SO4)2 at a concentration of 1–3 M. Alternatively, HI can be used as the iodine-based active material at a concentration of 1–6 M; the additives can be one or more of NaBr, KBr, NaCl, and KCl at a concentration of 1–3 M; the supporting electrolyte H2SO4 can be at a concentration of 2–4 M; and the active material for Cd can be Cd(SO4)2 at a concentration of 1–3 M. Alternatively, CdI2 can be selected as the active material at a concentration of 0.5–3 M; HBr and / or HCl can be selected as additives at a concentration of 1–3 M; and the supporting electrolyte H2SO4 can be selected at a concentration of 2–4 M. Alternatively, CdI2 can be selected as the active material at a concentration of 0.5–3 M; and one or more of the following additives can be selected: NaBr, KBr, NaCl, and KCl at a concentration of 1–3 M; then the concentration of the supporting electrolyte H2SO4 needs to be maintained at 3–5 M. Alternatively, NaI and / or KI can be selected as the active material at a concentration of 1–6 M; HBr and / or HCl can be selected as additives at a concentration of 1–3 M; then the concentration of the supporting electrolyte H2SO4 is 2–4 M; and the active material for Cd is Cd(SO4)2 at a concentration of 1–3 M. Alternatively, NaI and / or KI can be selected as the active material at a concentration of 1–6 M; and one or more of the additives NaBr, KBr, NaCl, and KCl can be selected at a concentration of 1–3 M; then the concentration of the supporting electrolyte H2SO4 needs to be maintained at 3–5 M, and the active material for Cd is Cd(SO4)2 at a concentration of 1–3 M.

6. The battery according to claim 5, characterized in that: The specific compositions of the positive and negative electrolytes are as follows: HI is used as the iodine-based active material at a concentration of 6M; HBr and / or HCl are used as additives at a concentration of 3M; the supporting electrolyte H2SO4 has a concentration of 1M; and the active material for Cd is Cd(SO4)2 at a concentration of 3M. Alternatively, HI can be used as the iodine-based active material at a concentration of 6 M; the additives can be one or more of NaBr, KBr, NaCl, and KCl at a concentration of 3 M; the supporting electrolyte H2SO4 at a concentration of 2 M; and the active material for Cd can be Cd(SO4)2 at a concentration of 3 M. Alternatively, CdI2 can be selected as the active material at a concentration of 3 M; HBr and / or HCl can be selected as additives at a concentration of 3 M; then the supporting electrolyte H2SO4 should be at a concentration of 4 M. Alternatively, CdI2 can be selected as the active material at a concentration of 3 M; and one or more of the additives NaBr, KBr, NaCl, and KCl can be selected at a concentration of 3 M; then the concentration of the supporting electrolyte H2SO4 needs to be maintained at 5 M. Alternatively, NaI and / or KI can be selected as the active material at a concentration of 6 M; HBr and / or HCl can be selected as the additive at a concentration of 3 M; then the supporting electrolyte H2SO4 at a concentration of 4 M; and the active material for Cd can be Cd(SO4)2 at a concentration of 3 M. Alternatively, NaI and / or KI can be selected as the active material at a concentration of 6 M; and one or more of the additives NaBr, KBr, NaCl, and KCl can be selected at a concentration of 3 M; then the concentration of the supporting electrolyte H2SO4 needs to be maintained at 5 M, and the active material of Cd is Cd(SO4)2 at a concentration of 3 M.

7. The battery according to any one of claims 1-6, characterized in that: The battery membrane material is Nafion resin.

8. The battery according to claim 1, characterized in that: A battery includes a single cell or a stack. The structure of a single cell includes a positive terminal plate, a positive current collector, a positive carbon felt electrode filled with positive electrolyte, a separator, a negative carbon felt electrode filled with negative electrolyte, a negative current collector, and a negative terminal plate stacked in sequence. A stack is composed of two or more single cell circuits connected in series and / or in parallel.

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