Energy regeneration liquid and energy regeneration method of electrochemical energy storage device

Abstract

The invention provides energy regeneration liquid of an electrochemical energy storage device. The energy regeneration liquid comprises the following raw materials in parts by weight: 8-10 parts of lithium halide and 86-88 parts of an organic solvent. The invention further provides an energy regeneration method which comprises the following steps: selecting the raw materials according to the proportion, preparing the raw materials into the energy regeneration liquid, adding the energy regeneration liquid into the lithium battery with capacity fading, completely discharging the lithium battery and then completely charging the lithium battery, and completing energy regeneration after a plurality of cycles. The lithium metal is directly used as a lithium source to be supplemented into the lithium battery, and lithium ions are generated along with charging and discharging of the battery to supplement loss of the lithium ions in the electrolyte and the positive electrode material, so that the battery capacity is maintained at a relatively high level for a long time while the battery capacity is improved, and the repairing effect and the continuity of the repairing function are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy regeneration of electrochemical energy storage devices, and in particular to an energy regeneration liquid and an energy regeneration method of an electrochemical energy storage device. Background Art

[0002] Over the past few decades, lithium-ion batteries have been widely used in various applications, such as consumer electronics, due to their superior energy density, long life and discharge capacity. Lithium-ion batteries generally include an anode, an electrolyte and a cathode, the cathode containing lithium in the form of lithium transition metal oxides.

[0003] In recent years, lithium-ion batteries have been used extensively in the automotive propulsion sector, as these batteries provide many years of reliable service and are expected to last about 10 years under normal driving conditions. Subsequently, these lithium-ion batteries can be used for utility energy storage until the end of their useful life.

[0004] Then, the calendar service life requirements of batteries for new energy vehicles and power storage systems are much higher than the life requirements of consumer small batteries, and existing lithium-ion batteries cannot meet the requirements within one life cycle. When the battery is used a certain number of times, the battery performance decays, and the decayed battery can no longer be used normally. At present, the battery is generally disassembled, crushed and recycled after failure, which not only pollutes the environment and consumes a lot of energy, but can only recycle limited metal ions. Therefore, it is very important to find new technical ways to repair and regenerate batteries with decayed capacity but still useful value, and further increase the service life of energy storage batteries.

[0005] At present, the existing energy regeneration technology mainly opens the battery cell injection hole and injects new electrolyte into the battery cell. Although this method can partially repair lithium-ion batteries, it only solves the capacity drop caused by electrolyte decomposition failure, and the capacity that can be repaired is limited. If new lithium sources cannot be added and active lithium metal is introduced, it will still decay again in a short time. Therefore, a better energy regeneration technology is needed. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides an energy regeneration liquid and an energy regeneration method for an electrochemical energy storage device, which solves the problem that the energy repair method in the prior art cannot introduce new active lithium metal as a lithium source, resulting in limited repair capacity and easy attenuation again.

[0007] In a first aspect, the present invention provides an energy regeneration liquid for an electrochemical energy storage device, comprising the following raw materials in parts by weight: 8-10 parts of lithium halide and 86-88 parts of an organic solvent.

[0008] Preferably, the lithium halide comprises a mixture of one or more of lithium chloride, lithium bromide and lithium iodide.

[0009] Preferably, the organic solvent comprises one or a mixture of two of a carbonate solvent and an ether solvent.

[0010] Preferably, the carbonate solvent includes a mixture of one or more of dimethyl carbonate, ethyl methyl carbonate and ethylene carbonate.

[0011] Preferably, the ether solvent includes a mixture of one or more of dimethyl ether, tetrahydrofuran and diethyl ether.

[0012] Preferably, it also includes 2-4 parts of additives calculated by weight.

[0013] Preferably, the additive includes one of fluoroethylene carbonate and vinylene carbonate or a mixture of the two.

[0014] In a second aspect, the present invention provides an energy regeneration method, comprising the following steps:

[0015] S1. Select raw materials according to the ratio and prepare them into energy regeneration liquid;

[0016] S2, adding energy regeneration liquid into the lithium battery with capacity decay;

[0017] S3. The lithium battery is fully discharged and then fully charged to complete energy regeneration after several cycles.

[0018] Furthermore, when the energy regeneration liquid is added in step S2, the mass of the energy regeneration liquid / battery capacity is 0.0017-0.0023 g / mAh.

[0019] The technical principle of the present invention is: lithium halide is added to the regeneration liquid, so that the lithium ions and halogen ions therein can undergo an oxidation reaction. During the charging process, the halogen ions undergo an oxidation reaction at the positive electrode to generate a halogen element, and the negative electrode undergoes a reduction reaction to generate lithium metal, thereby evenly embedding the lithium metal into the graphite negative electrode. In this way, the active lithium metal is directly placed inside the lithium-ion battery, and the lithium metal can be oxidized into lithium ions at any time during the discharge process, thereby replenishing the lithium ion loss in the electrolyte and the positive electrode material.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention directly adds lithium metal as a lithium source to the lithium battery, and generates lithium ions as the battery charges and discharges to supplement the loss of lithium ions in the electrolyte and the positive electrode material, thereby increasing the battery capacity while maintaining the battery capacity at a high level for a long time, thereby improving the repair effect and the sustainability of the repair function;

[0022] 2. After charging, the present invention generates lithium metal at the negative electrode and forms a single halogen in the positive electrode or the electrolyte, thereby forming another lithium battery structure. The conversion of lithium and halogen in single substance and ionic state is maintained through the charging and discharging process, and a stable structure is constructed, so that lithium ions are not easily lost due to long-term use, and the proportion of capacity reduction due to lithium ion loss is reduced. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. It should be noted that the embodiments described below are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0024] Embodiment 1:

[0025] The energy regeneration liquid in this embodiment includes the following raw materials in parts by weight:

[0026] 8 parts of lithium iodide, 30 parts of dimethyl carbonate, 28 parts of ethyl methyl carbonate, 30 parts of ethylene carbonate, 2 parts of fluoroethylene carbonate, and 2 parts of vinylene carbonate.

[0027] The energy regeneration method steps are as follows:

[0028] 2.5g of energy regeneration liquid was added to a 18650 cylindrical battery (diameter 18.4mm, height 65.2mm) with capacity decay. The electrode material of the battery was LFP (lithium iron phosphate) system with a residual capacity of 1232mAh. Then, it was discharged and charged with a small current density of 0.1C, and energy regeneration was completed after 3 cycles.

[0029] Embodiment 2:

[0030] The energy regeneration liquid in this embodiment includes the following raw materials in parts by weight:

[0031] 10 parts of lithium bromide, 30 parts of dimethyl carbonate, 18 parts of ethyl methyl carbonate, 28 parts of ethylene carbonate, 10 parts of dimethyl ether, 1 part of fluoroethylene carbonate, and 1 part of vinylene carbonate.

[0032] The energy regeneration method steps are as follows:

[0033] 2.9g of energy regeneration liquid was added to a 18650 cylindrical battery (diameter 18.4mm, height 65.2mm) with capacity decay. The electrode material of the battery was LFP (lithium iron phosphate) system with a residual capacity of 1243mAh. Then, it was discharged and charged with a small current density of 0.1C, and energy regeneration was completed after 3 cycles.

[0034] Embodiment 3:

[0035] The energy regeneration liquid in this embodiment includes the following raw materials in parts by weight:

[0036] 9 parts of lithium chloride, 30 parts of dimethyl carbonate, 18 parts of ethyl methyl carbonate, 30 parts of ethylene carbonate, 6 parts of ether, 4 parts of tetrahydrofuran, 2 parts of fluoroethylene carbonate, and 1 part of vinylene carbonate.

[0037] The energy regeneration method steps are as follows:

[0038] 2.1g of energy regeneration liquid was added to a 18650 cylindrical battery (diameter 18.4mm, height 65.2mm) with capacity decay. The electrode material of the battery was LFP (lithium iron phosphate) system with a residual capacity of 1234mAh. Then, it was discharged and charged with a small current density of 0.1C, and energy regeneration was completed after 2 cycles.

[0039] Embodiment 4:

[0040] The energy regeneration liquid in this embodiment includes the following raw materials in parts by weight:

[0041] 8 parts of lithium iodide, 30 parts of dimethyl carbonate, 28 parts of ethyl methyl carbonate, 30 parts of ethylene carbonate, 2 parts of fluoroethylene carbonate, and 2 parts of vinylene carbonate.

[0042] The energy regeneration method steps are as follows:

[0043] 5.1g of energy regeneration liquid was added to a 26650 cylindrical battery (26.2mm in diameter and 65.1mm in height) with a capacity decay. The electrode material of the battery was NCM (nickel cobalt manganese oxide) system with a residual capacity of 2812mAh. Then, the battery was discharged and charged with a small current density of 0.1C, and energy regeneration was completed after 3 cycles.

[0044] Embodiment 5:

[0045] The energy regeneration liquid in this embodiment includes the following raw materials in parts by weight:

[0046] 4 parts of lithium iodide, 4 parts of lithium bromide, 88 parts of dimethyl carbonate, and 3 parts of fluoroethylene carbonate.

[0047] The energy regeneration method steps are as follows:

[0048] 2.4g of energy regeneration liquid was added to a 18650 cylindrical battery (diameter 18.4mm, height 65.2mm) with capacity decay. The electrode material of the battery was LFP (lithium iron phosphate) system with a residual capacity of 1228mAh. Then, it was discharged and charged with a small current density of 0.1C, and energy regeneration was completed after 3 cycles.

[0049] Embodiment 6:

[0050] The energy regeneration liquid in this embodiment includes the following raw materials in parts by weight:

[0051] 8 parts of lithium iodide, 88 parts of dimethyl ether, 2 parts of fluoroethylene carbonate, and 2 parts of vinylene carbonate.

[0052] The energy regeneration method steps are as follows:

[0053] 2.5g of energy regeneration liquid was added to a 18650 cylindrical battery (diameter 18.4mm, height 65.2mm) with capacity decay. The electrode material of the battery was LFP (lithium iron phosphate) system with a residual capacity of 1231mAh. Then, it was discharged and charged with a small current density of 0.1C, and energy regeneration was completed after 3 cycles.

[0054] Comparative Example:

[0055] A new electrolyte was prepared with 30 parts of dimethyl carbonate, 28 parts of ethyl methyl carbonate, 30 parts of ethylene carbonate, 2 parts of fluoroethylene carbonate and 2 parts of vinylene carbonate as raw materials. The old electrolyte in the 18650 cylindrical battery (diameter 18.4mm, height 65.2mm) with capacity decay was drained and filled with new electrolyte. The electrode material of the battery was LFP (lithium iron phosphate) system with a residual capacity of 1236mAh. Then, it was discharged and charged with a small current with a current density of 0.1C, and energy regeneration was completed after 3 cycles.

[0056] The capacity and internal resistance of the repaired lithium-ion batteries in Examples 1-6 and the comparative example were tested, and the results are shown in Table 1.

[0057]

[0058] Table 1

[0059] As shown in Table 1, after the energy regeneration liquid prepared in the present invention is used to regenerate the energy of the lithium-ion battery with declining capacity, the battery capacity of the regenerated lithium-ion battery is significantly improved more than the method of only replacing and adding new electrolyte in the comparative example. In addition, the internal resistance of the lithium-ion battery regenerated by the present invention is also lower, which fully demonstrates the superior technical effect of the present invention.

[0060] Finally, it is explained that the above embodiments are only used to illustrate the technical solution of the present invention and are not intended to limit it. In this article, relational terms such as "first" and "second" etc. are only used to distinguish an entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only include those elements, but also include other elements not clearly listed, or also include elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the statement "include one..." do not exclude that there are other identical ones in the process, method, article or equipment including the elements.

Claims

1. An energy regeneration liquid for an electrochemical energy storage device, characterized in that: The invention comprises the following raw materials in parts by weight: 8-10 parts of lithium halide and 86-88 parts of organic solvent.

2. The energy regeneration liquid of an electrochemical energy storage device according to claim 1, characterized in that: The lithium halide includes a mixture of one or more of lithium chloride, lithium bromide and lithium iodide.

3. The energy regeneration liquid of an electrochemical energy storage device according to claim 1, characterized in that: The organic solvent includes one or a mixture of two of a carbonate solvent and an ether solvent.

4. The energy regeneration liquid of an electrochemical energy storage device according to claim 3, characterized in that: The carbonate solvent includes a mixture of one or more of dimethyl carbonate, ethyl methyl carbonate and ethylene carbonate.

5. The energy regeneration liquid of an electrochemical energy storage device according to claim 3, characterized in that: The ether solvent includes a mixture of one or more of dimethyl ether, tetrahydrofuran and diethyl ether.

6. The energy regeneration liquid of an electrochemical energy storage device according to claim 1, characterized in that: The invention also comprises 2-4 parts of additives calculated by weight.

7. The energy regeneration liquid of an electrochemical energy storage device according to claim 6, characterized in that: The additive includes one of fluoroethylene carbonate and vinylene carbonate or a mixture of the two.

8. An energy regeneration method based on the energy regeneration liquid as claimed in claim 1, characterized in that: The steps include: S1. Select raw materials according to the ratio and prepare them into energy regeneration liquid; S2, adding energy regeneration liquid into the lithium battery with capacity decay; S3. The lithium battery is fully discharged and then fully charged to complete energy regeneration after several cycles.

9. An energy regeneration method as claimed in claim 8, characterized in that: When the energy regeneration liquid is added in step S2, the mass of the energy regeneration liquid / battery capacity is 0.0017-0.0023 g / mAh.

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