技术领域Technical Field
本发明属于化学电源技术领域，特别是一种锂金属二次电池用高功率电解液及制备方法与应用。The invention belongs to the technical field of chemical power sources, in particular to a high-power electrolyte for lithium metal secondary batteries and a preparation method and application thereof.
背景技术Background technique
近年来，随着能源需求多样化的发展，对高能量密度、长循环寿命能源存储系统提出了更高的要求。金属锂具有最高的理论容量(3860mAh/g)和最负的电化学电位(-3.04V)。与现有的锂离子电池负极材料相比，金属锂负极在满足高能量密度需求方面具有巨大潜力。尽管金属锂负极呈现出优越的理论容量和能量密度，但其在应用过程中由于界面的不稳定性存在以下问题：(1)锂枝晶生长带来的安全性问题；(2)不可逆的副反应导致活性材料的快速损失和电池阻抗的快速增加，锂金属二次电池倍率性能较差；(3)金属锂“无宿主”的性质导致电极的粉化，锂金属二次电池循环寿命低。对于金属锂负极界面稳定性的研究工作，科研工作者分别从电解液改性、界面保护层、结构化电极等方面进行研究。人工构建界面保护层及结构化电极的实现过程通常较为复杂，且目前相关研究均停留在小面积扣式电池负极水平，难以实现大面积工程化应用。目前锂金属二次电池适配电解液优化是改善锂金属二次电池倍率性能以及循环性能的有效手段，并且通过电解液优化易于实现工程化应用，在未来高比能金属锂体系电池的应用方面具有巨大潜力。In recent years, with the development of diversified energy demand, higher requirements have been put forward for energy storage systems with high energy density and long cycle life. Lithium metal has the highest theoretical capacity (3860mAh/g) and the most negative electrochemical potential (-3.04V). Compared with existing lithium-ion battery anode materials, lithium metal anode has great potential in meeting the demand for high energy density. Although lithium metal anode has superior theoretical capacity and energy density, it has the following problems in application due to the instability of the interface: (1) Safety issues caused by lithium dendrite growth; (2) Irreversible side reactions lead to rapid loss of active materials and rapid increase of battery impedance, and the rate performance of lithium metal secondary batteries is poor; (3) The "host-free" nature of lithium metal leads to pulverization of electrodes, and the cycle life of lithium metal secondary batteries is low. For the research work on the interface stability of lithium metal anode, researchers have conducted research from the aspects of electrolyte modification, interface protection layer, structured electrode, etc. The process of artificially constructing interface protection layer and structured electrode is usually complicated, and the current related research is still at the level of small-area button battery anode, which is difficult to achieve large-area engineering application. At present, electrolyte optimization for lithium metal secondary batteries is an effective means to improve the rate performance and cycle performance of lithium metal secondary batteries. In addition, it is easy to realize engineering applications through electrolyte optimization, and it has great potential in the application of high-energy-density lithium metal system batteries in the future.
发明内容Summary of the invention
针对现有技术存在的问题，本发明提供了一种锂金属二次电池用高功率电解液及制备方法与应用。所述电解液由醚类有机溶剂、电解质、添加剂和稀释剂组成。所述电解液在金属锂负极生成富含无机锂盐的氟化物固态电解质界面膜(SEI)，通过电解液无机界面层的保护作用，从而实现有效提升锂金属二次电池倍率性能以及循环稳定性能。所述电解液通过添加剂的引入在镍钴锰酸锂、钴酸锂等高电压正极表面生成高电位稳定的电解质界面膜(CEI)，且该界面膜具有良好的离子传输能力，从而有效提升电池倍率性能。In view of the problems existing in the prior art, the present invention provides a high-power electrolyte for lithium metal secondary batteries, a preparation method and an application thereof. The electrolyte is composed of an ether organic solvent, an electrolyte, an additive and a diluent. The electrolyte generates a fluoride solid electrolyte interface film (SEI) rich in inorganic lithium salts at the metal lithium negative electrode, and through the protective effect of the inorganic interface layer of the electrolyte, the rate performance and cycle stability of the lithium metal secondary battery are effectively improved. The electrolyte generates a high-potential stable electrolyte interface film (CEI) on the surface of high-voltage positive electrodes such as lithium nickel cobalt manganese oxide and lithium cobalt oxide through the introduction of additives, and the interface film has good ion transmission capacity, thereby effectively improving the battery rate performance.
本发明为解决锂金属二次电池高倍率放电等技术问题所采取的技术方案是：一种锂金属二次电池用高功率电解液，电解液由醚类有机溶剂、锂盐电解质、添加剂和稀释剂组成，电解液的锂盐浓度为1.5mol/L～4mol/L，离子电导率为1mS/cm～10mS/cm。The technical solution adopted by the present invention to solve the technical problems such as high-rate discharge of lithium metal secondary batteries is: a high-power electrolyte for lithium metal secondary batteries, the electrolyte consists of an ether organic solvent, a lithium salt electrolyte, an additive and a diluent, the lithium salt concentration of the electrolyte is 1.5 mol/L to 4 mol/L, and the ion conductivity is 1 mS/cm to 10 mS/cm.
所述添加剂为1,3-丙磺酸内酯、1,3-丙烯磺酸内酯、硫酸亚乙酯、碳酸亚乙烯酯、亚磷酸三苯酯、三(三甲基硅烷)磷酸酯、三(三甲基硅烷)硼酸酯中的一种或多种。The additive is one or more of 1,3-propane sultone, 1,3-propylene sultone, ethylene sulfate, vinylene carbonate, triphenyl phosphite, tris(trimethylsilane) phosphate, and tris(trimethylsilane) borate.
所述醚类有机溶剂为乙二醇二甲醚、二乙二醇二甲醚、三乙二醇二甲醚、四乙二醇二甲醚、二乙二醇二乙醚、三乙二醇二乙醚中的一种或多种。The ether organic solvent is one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether and triethylene glycol diethyl ether.
所述稀释剂为R1—O—R2，其中R1和R2为C1～C6的氟代烷基。The diluent is R1 —O—R2 , wherein R1 and R2 are C1-C6 fluoroalkyl groups.
所述稀释剂为1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、全氟壬烯基三氟乙醚、1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚、1H,1H,5H-八氟戊基-1,1,2,2-四氟乙基醚中一种或多种。The diluent is one or more of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, perfluorononenyl trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether.
所述锂盐电解质为二氟磷酸锂、六氟磷酸锂、双三氟甲烷磺酰亚胺锂、双氟磺酰亚胺锂、二氟草酸硼酸锂、二草酸硼酸锂中的一种或两种的混合。The lithium salt electrolyte is one of lithium difluorophosphate, lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), lithium difluorooxalatoborate, and lithium dioxalatoborate, or a mixture of two of them.
如上述锂金属二次电池用高功率电解液的制备方法，在惰性气体保护下，将一定重量的电解质锂盐加到按比例混合均匀的醚类有机溶剂和稀释剂中，并在25℃～40℃范围内搅拌0.5h～3h，待锂盐溶解后，向电解液中加入0.2％～1.0％比例一定重量的添加剂，并在25～40℃范围内搅拌0.5h～3h。As mentioned above, in the method for preparing a high-power electrolyte for a lithium metal secondary battery, a certain weight of electrolyte lithium salt is added to an ether organic solvent and a diluent that are evenly mixed in proportion under the protection of an inert gas, and stirred for 0.5h to 3h at a temperature between 25°C and 40°C. After the lithium salt is dissolved, a certain weight of an additive in a ratio of 0.2% to 1.0% is added to the electrolyte, and stirred for 0.5h to 3h at a temperature between 25°C and 40°C.
具体包括以下步骤：The specific steps include:
步骤一，在惰性气体保护下，将一定配比的醚类有机溶剂和稀释剂在20℃～25℃范围内搅拌0.2h～0.5h混匀；Step 1: Under the protection of inert gas, stir a certain ratio of ether organic solvent and diluent at 20°C to 25°C for 0.2h to 0.5h to mix;
步骤二，将一定重量的锂盐电解质加入混匀的溶剂中，并在25℃～40℃范围内搅拌0.5h～3h；Step 2, adding a certain weight of lithium salt electrolyte to the mixed solvent, and stirring at 25° C. to 40° C. for 0.5 h to 3 h;
步骤三，待锂盐电解质溶解后，向电解液中加入一定重量的添加剂，并在25℃～40℃范围内搅拌0.5h～3h。Step 3: After the lithium salt electrolyte is dissolved, a certain weight of additives is added to the electrolyte and stirred at 25° C. to 40° C. for 0.5 h to 3 h.
一种采用上述电解液的锂金属二次电池，包括正极、负极、隔膜、铝塑膜，其特征在于，正极为镍钴锰酸锂、钴酸锂、富锂锰基氧化物正极中的一种；负极为金属锂带、金属锂镁合金、金属锂铝合金、金属锂硼合金中的一种；隔膜为单层聚丙烯隔膜、三层聚丙烯-聚乙烯复合隔膜、聚丙烯-氧化铝陶瓷涂层复合隔膜中的一种。A lithium metal secondary battery using the above-mentioned electrolyte includes a positive electrode, a negative electrode, a diaphragm, and an aluminum-plastic film, characterized in that the positive electrode is one of lithium nickel cobalt manganese oxide, lithium cobalt oxide, and a lithium-rich manganese-based oxide positive electrode; the negative electrode is one of a metal lithium strip, a metal lithium magnesium alloy, a metal lithium aluminum alloy, and a metal lithium boron alloy; and the diaphragm is one of a single-layer polypropylene diaphragm, a three-layer polypropylene-polyethylene composite diaphragm, and a polypropylene-alumina ceramic coating composite diaphragm.
本发明具有的有益效果：所述电解液通过所述添加剂与所述有机溶剂、所述稀释剂、所述锂盐和所述添加剂的共同作用，在锂金属二次电池的正极和负极的表面形成界面膜。其中：The present invention has the beneficial effect that the electrolyte forms an interface film on the surface of the positive electrode and the negative electrode of the lithium metal secondary battery through the combined action of the additive, the organic solvent, the diluent, the lithium salt and the additive.
(1)在正极表面生成的高电位稳定的电解质界面膜(CEI)，可有效抑制锂金属二次电池在长寿命循环过程中的正极过渡金属溶出，有效提高电池的容量保持率，提升电池的循环稳定性；(1) The high-potential stable electrolyte interface film (CEI) generated on the positive electrode surface can effectively inhibit the dissolution of positive electrode transition metals in the long-life cycle of lithium metal secondary batteries, effectively improve the capacity retention rate of the battery, and enhance the cycle stability of the battery;
(2)通过电解液配方优化在金属锂负极表面原位生成富含无机锂盐的氟化物(LiF)固态电解质界面膜(SEI)，LiF具有较高的表面能，促进锂沿表面致密沉积，减少枝晶状及海绵状锂沉积，该SEI膜能够降低锂金属二次电池循环过程的内阻，从而提升锂金属二次电池倍率放电性能。(2) By optimizing the electrolyte formula, a solid electrolyte interface film (SEI) rich in inorganic lithium salt fluoride (LiF) is in situ generated on the surface of the metal lithium negative electrode. LiF has a high surface energy, which promotes the dense deposition of lithium along the surface and reduces the dendritic and sponge-like lithium deposition. The SEI film can reduce the internal resistance of the lithium metal secondary battery during the cycle process, thereby improving the rate discharge performance of the lithium metal secondary battery.
此外，本发明所述的电解液制备工艺简便，制备效率高，在锂金属二次电池的实际应用中提供可工程化方案，大幅度提高锂金属二次电池的整体性能，有利于提高电池的市场应用前景，具有重大的生产实践意义。In addition, the electrolyte preparation process described in the present invention is simple and has high preparation efficiency. It provides an engineering solution in the actual application of lithium metal secondary batteries, greatly improves the overall performance of lithium metal secondary batteries, is conducive to improving the market application prospects of batteries, and has great production practice significance.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
图1为使用实施例1与对比例电解液的锂金属二次电池倍率放电性能；FIG1 shows the rate discharge performance of lithium metal secondary batteries using electrolytes of Example 1 and Comparative Example;
图2为使用实施例1与对比例电解液的锂金属二次电池循环容量保持率对比图。FIG. 2 is a comparison chart of the cycle capacity retention rates of lithium metal secondary batteries using the electrolytes of Example 1 and the comparative example.
具体实施方式Detailed ways
下面详细描述本发明的实施例，所述实施例的示例在附图中示出。下面通过参考附图描述的实施例是示例性的，旨在用于解释本发明，而不能理解为对本发明的限制。Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.
本发明实施例提供一种锂金属二次电池用的电解液，用于抑制锂金属二次电池在循环过程中的体积膨胀。该电解液包括：有机溶剂、稀释剂、添加剂和锂盐，其中有机溶剂和稀释剂均为醚类，稀释剂含有碳原子数为1～10的氟代烷基，添加剂为酯类；该电解液中，添加剂的质量分数为0.5％～10％，锂盐的浓度为1.5mol/L～4mol/L。添加剂用于配合有机溶剂、稀释剂和锂盐，以在锂金属二次电池的电极表面形成界面膜。The embodiment of the present invention provides an electrolyte for a lithium metal secondary battery, which is used to suppress the volume expansion of the lithium metal secondary battery during the cycle process. The electrolyte includes: an organic solvent, a diluent, an additive and a lithium salt, wherein the organic solvent and the diluent are both ethers, the diluent contains a fluoroalkyl group with a carbon number of 1 to 10, and the additive is an ester; in the electrolyte, the mass fraction of the additive is 0.5% to 10%, and the concentration of the lithium salt is 1.5 mol/L to 4 mol/L. The additive is used to cooperate with the organic solvent, the diluent and the lithium salt to form an interface film on the electrode surface of the lithium metal secondary battery.
电解液的离子电导率为1mS/cm～10mS/cm。The ion conductivity of the electrolyte is 1 mS/cm to 10 mS/cm.
有机溶剂包括乙二醇二甲醚、二乙二醇二甲醚、三乙二醇二甲醚、四乙二醇二甲醚、二乙二醇二乙醚、三乙二醇二乙醚中的至少一种。优选的，有机溶剂选用乙二醇二甲醚和三乙二醇二甲醚。The organic solvent includes at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether and triethylene glycol diethyl ether. Preferably, the organic solvent is ethylene glycol dimethyl ether and triethylene glycol dimethyl ether.
稀释剂包括1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、全氟壬烯基三氟乙醚、1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚、1H,1H,5H-八氟戊基-1,1,2,2-四氟乙基醚中的至少一种。优选的稀释剂选用1,1,2,2-四氟乙基-2,2,2-三氟乙基醚。含有该稀释剂的电解液在金属锂负极生成富含无机锂盐的氟化物(LiF)固态电解质界面膜(SEI)，LiF具有较高的表面能，能促进锂沿负极表面致密沉积，减少枝晶状及海绵状锂沉积，可有效提升负极的界面稳定性，降低界面电阻，有效提升锂金属二次电池的放电倍率性能和循环稳定性。The diluent includes at least one of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, perfluorononenyl trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether. The preferred diluent is 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether. The electrolyte containing the diluent generates a fluoride (LiF) solid electrolyte interface film (SEI) rich in inorganic lithium salts at the metal lithium negative electrode. LiF has a high surface energy, which can promote the dense deposition of lithium along the negative electrode surface, reduce dendritic and spongy lithium deposition, and can effectively improve the interface stability of the negative electrode, reduce the interface resistance, and effectively improve the discharge rate performance and cycle stability of the lithium metal secondary battery.
添加剂包括1,3-丙磺酸内酯、1,3-丙烯磺酸内酯、硫酸亚乙酯、碳酸亚乙烯酯、亚磷酸三苯酯、三(三甲基硅烷)磷酸酯、三(三甲基硅烷)硼酸酯中的至少一种。该添加剂与有机溶剂、稀释剂和锂盐的共同作用下，在锂金属二次电池的正极和负极的表面形成界面膜，其中，在正极表面生成的高电位稳定的电解质界面膜(CEI)，可有效抑制锂金属二次电池在长寿命循环过程中的正极过渡金属溶出，有效提高电池的容量保持率，提升电池的循环稳定性。The additive includes at least one of 1,3-propane sultone, 1,3-propylene sultone, ethylene sulfate, vinylene carbonate, triphenyl phosphite, tris(trimethylsilyl) phosphate, and tris(trimethylsilyl) borate. Under the combined action of the additive, organic solvent, diluent, and lithium salt, an interface film is formed on the surface of the positive electrode and the negative electrode of the lithium metal secondary battery. The high-potential stable electrolyte interface film (CEI) generated on the positive electrode surface can effectively inhibit the dissolution of the positive electrode transition metal of the lithium metal secondary battery during the long-life cycle, effectively improve the capacity retention rate of the battery, and enhance the cycle stability of the battery.
锂盐包括二氟磷酸锂、六氟磷酸锂、双三氟甲烷磺酰亚胺锂、双氟磺酰亚胺锂、二氟草酸硼酸锂、二草酸硼酸锂中的一种或两种。The lithium salt includes one or two of lithium difluorophosphate, lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide), lithium difluorooxalatoborate, and lithium dioxalatoborate.
本发明还提供一种锂金属二次电池用的电解液的制备方法，包括步骤：The present invention also provides a method for preparing an electrolyte for a lithium metal secondary battery, comprising the steps of:
s1、在惰性气体的保护下，将锂盐加入到有机溶剂和稀释剂中，充分搅拌至澄清透明；s1. Under the protection of inert gas, add lithium salt to organic solvent and diluent, and stir thoroughly until clear and transparent;
s2、向步骤s1中得到的溶液中加入添加剂，充分搅拌至澄清透明。s2. Add additives to the solution obtained in step s1 and stir thoroughly until it becomes clear and transparent.
有机溶剂和稀释剂的体积比为1:1.5。The volume ratio of the organic solvent to the diluent is 1:1.5.
由于锂盐易受热分解，故制备电解液时应控制电解液的温度和搅拌的时长。在一些实施例中，电解液的制备温度为25℃～40℃，搅拌时间为0.5h～3h。Since lithium salts are susceptible to thermal decomposition, the temperature of the electrolyte and the stirring time should be controlled when preparing the electrolyte. In some embodiments, the preparation temperature of the electrolyte is 25°C to 40°C, and the stirring time is 0.5h to 3h.
本发明实施例还提供一种锂金属二次电池，该二次电池包括正极、负极、隔膜和铝塑膜，以及如上所述的锂金属二次电池用的电解液。An embodiment of the present invention further provides a lithium metal secondary battery, which includes a positive electrode, a negative electrode, a separator and an aluminum-plastic film, and the electrolyte for the lithium metal secondary battery as described above.
该二次电池的正极为镍钴锰酸锂正极、钴酸锂正极正极；负极为金属锂带、金属锂镁合金、金属锂铝合金或金属锂硼合金；隔膜为单层聚丙烯隔膜、三层聚丙烯-聚乙烯复合隔膜或聚丙烯-氧化铝陶瓷涂层复合隔膜。The positive electrode of the secondary battery is a nickel cobalt manganese oxide positive electrode or a lithium cobalt oxide positive electrode; the negative electrode is a metal lithium strip, a metal lithium magnesium alloy, a metal lithium aluminum alloy or a metal lithium boron alloy; the diaphragm is a single-layer polypropylene diaphragm, a three-layer polypropylene-polyethylene composite diaphragm or a polypropylene-alumina ceramic coating composite diaphragm.
本发明先后进行过多次实验，现列举部分实验结果作为参考对发明进一步详细描述，下面结合具体实施例进行详细说明。The present invention has been subjected to multiple experiments, and some experimental results are listed as references to further describe the invention in detail, which is described in detail below in conjunction with specific embodiments.
实施例1：Embodiment 1:
制备金属锂离子电池用电解液：Preparation of electrolyte for metal lithium ion batteries:
s1、在氩气气氛手套箱中，将三乙二醇二甲醚和1,1,2,2-四氟乙基-2,2,2-三氟乙基醚按照体积比1:1.5的比例在25℃下磁力搅拌0.5h搅拌均匀，然后将双三氟甲烷磺酰亚胺锂以4.0mol/L的摩尔浓度加入混合溶剂中，并使用磁力搅拌器在30℃的条件下搅拌2小时，直至锂盐完全溶解，溶液澄清透明；s1. In an argon atmosphere glove box, triethylene glycol dimethyl ether and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether were stirred evenly at a volume ratio of 1:1.5 under magnetic stirring at 25°C for 0.5 h, and then lithium bistrifluoromethanesulfonyl imide was added to the mixed solvent at a molar concentration of 4.0 mol/L, and stirred at 30°C for 2 hours using a magnetic stirrer until the lithium salt was completely dissolved and the solution was clear and transparent;
s2、向步骤s1中得到的溶液中加入碳酸亚乙烯酯，碳酸亚乙烯酯占制备得到的电解液的总质量的2％，然后使用磁力搅拌器在25℃的条件下搅拌1h，至溶液澄清透明，得到锂金属二次电池用的电解液。s2. Add vinylene carbonate to the solution obtained in step s1, where vinylene carbonate accounts for 2% of the total mass of the prepared electrolyte, and then use a magnetic stirrer to stir at 25° C. for 1 hour until the solution is clear and transparent, to obtain an electrolyte for a lithium metal secondary battery.
制备锂金属二次电池：Preparation of lithium metal secondary batteries:
s1、正极制备：将97wt％的正极活性材料镍钴锰酸锂(NCM811)、1wt％导电碳黑和0.5wt％导电剂碳纳米管组成的导电剂、1.5wt％粘接剂PVDF通过匀浆机均匀的分散在适量NMP溶剂中，其中PVDF在NMP溶剂中的占比为5wt％；将分散均匀的浆料涂覆在铝箔集流体上制备成正极，经分切碾压后获得正极极片。s1. Preparation of positive electrode: 97wt% of positive electrode active material lithium nickel cobalt manganese oxide (NCM811), 1wt% of conductive carbon black and 0.5wt% of conductive agent composed of carbon nanotubes, and 1.5wt% of adhesive PVDF are uniformly dispersed in an appropriate amount of NMP solvent through a homogenizer, wherein the proportion of PVDF in the NMP solvent is 5wt%; the uniformly dispersed slurry is coated on an aluminum foil current collector to prepare a positive electrode, and the positive electrode sheet is obtained after slitting and rolling.
s2、负极制备：将0.04mm厚的金属锂铝合金带裁切成合适尺寸后在固定位置使用油压机将铜极耳压合在锂片上，并将锂带被铜极耳覆盖的一侧压上相同尺寸和厚度的锂铝合金带进行补锂，以避免铜极耳覆盖处的容量损失，得到锂金属二次电池的负极极片。s2. Preparation of negative electrode: After cutting a 0.04 mm thick metal lithium aluminum alloy strip into a suitable size, use a hydraulic press to press the copper tab onto the lithium sheet at a fixed position, and press a lithium aluminum alloy strip of the same size and thickness on the side of the lithium strip covered by the copper tab to supplement lithium, so as to avoid capacity loss at the copper tab coverage, and obtain the negative electrode sheet of the lithium metal secondary battery.
s3、以叠片的方式按金属锂负极、聚丙烯-氧化铝陶瓷涂层复合隔膜、正极的顺序依次叠制相应的片数获得17Ah锂金属二次电池电芯，使用锂电池级铝塑膜进行封装，后经注液(注入上述制备得到的锂金属二次电池用的电解液，其注入量为1.5g/Ah)、浸润、化成、去气室等工艺流程制备锂金属二次软包电池。s3. Stack the corresponding number of sheets in the order of metal lithium negative electrode, polypropylene-alumina ceramic coating composite separator and positive electrode in a stacking manner to obtain a 17Ah lithium metal secondary battery cell, package it with a lithium battery grade aluminum-plastic film, and then prepare a lithium metal secondary soft-pack battery through the process of liquid injection (injecting the electrolyte for the lithium metal secondary battery prepared above, with an injection amount of 1.5g/Ah), infiltration, formation, and degassing chamber.
性能测试：Performance Testing:
倍率性能测试：使用充放电设备以0.2C的倍率进行充电至4.4V，然后以3C倍率放电至2.75V。Rate performance test: Use the charging and discharging equipment to charge to 4.4V at a rate of 0.2C, and then discharge to 2.75V at a rate of 3C.
循环性能测试：使用充放电设备以0.2C的倍率进行充放电循环性能测试，充电截止电压为4.4V，放电截止电压为2.75V。Cycle performance test: Use charge and discharge equipment to carry out charge and discharge cycle performance test at a rate of 0.2C, with a charge cut-off voltage of 4.4V and a discharge cut-off voltage of 2.75V.
对比实施例：Comparative Example:
与实施例1的区别在于，锂金属二次电池用的电解液的制备。本对比例中锂金属二次电池的制备及性能测试与实施例1一致。The difference from Example 1 is the preparation of the electrolyte for the lithium metal secondary battery. The preparation and performance test of the lithium metal secondary battery in this comparative example are consistent with those in Example 1.
在本对比例中，制备锂金属二次电池用的电解液的步骤包括：在氩气气氛手套箱中，将六氟磷酸锂以1.0mol/L的摩尔浓度加入氟代碳酸乙烯酯和碳酸甲乙酯(体积比1:2)混合溶剂中，并使用磁力搅拌器在30℃的条件下搅拌1小时，直至锂盐完全溶解，溶液澄清透明。随后将1,1,2,2-四氟乙基-2,2,2-三氟乙基醚以10wt％加入到上述溶液中，并使用磁力搅拌器在25℃的条件下搅拌1小时。In this comparative example, the steps of preparing an electrolyte for a lithium metal secondary battery include: in an argon atmosphere glove box, adding lithium hexafluorophosphate to a mixed solvent of fluoroethylene carbonate and ethyl methyl carbonate (volume ratio 1:2) at a molar concentration of 1.0 mol/L, and stirring at 30°C for 1 hour using a magnetic stirrer until the lithium salt is completely dissolved and the solution is clear and transparent. Subsequently, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether is added to the above solution at 10 wt%, and stirred at 25°C for 1 hour using a magnetic stirrer.
将实施例1及对比实施例的测试结果进行对比分析，对比结果参考图1-2。The test results of Example 1 and the comparative example are compared and analyzed, and the comparison results are shown in Figures 1-2.
锂金属二次电池倍率放电性能对比：从附图1中可以看出，在相同充放电制度下，使用实施例1中电解液电池相较于对比实施例中电解液的电池具有优异的倍率放电性能，电池3C放电容量较0.2C放电容量保持率更高；使用实施例1电解液的电池3C放电较0.2C放电容量保持率达96.03％，使用对照例电解液的电池3C放电较0.2C放电容量保持率达72.55％。上述结果表明实施例1电解液具有在金属锂负极表面生成致密且界面电阻小的SEI膜的作用，有效降低电池内阻，提升电池倍率放电性能。Comparison of rate discharge performance of lithium metal secondary batteries: As can be seen from Figure 1, under the same charge and discharge regime, the battery using the electrolyte in Example 1 has excellent rate discharge performance compared to the battery using the electrolyte in the comparative example, and the battery 3C discharge capacity retention rate is higher than the 0.2C discharge capacity retention rate; the battery using the electrolyte in Example 1 has a 3C discharge capacity retention rate of 96.03% compared to the 0.2C discharge capacity retention rate, and the battery using the electrolyte in the comparative example has a 3C discharge capacity retention rate of 72.55% compared to the 0.2C discharge capacity retention rate. The above results show that the electrolyte in Example 1 has the function of generating a dense SEI film with low interface resistance on the surface of the metal lithium negative electrode, effectively reducing the internal resistance of the battery and improving the battery rate discharge performance.
锂金属二次电池循环容量保持率对比：从图2可以看出，在相同的充放电制度下，实施例1相较于使用对比例电解液的电池具有更优异的循环稳定性，通过电解液的优化对锂金属二次电池的寿命性能有一定的提升。使用实施例1电解液的电池在贫液态下稳定循环155周后容量保持率仍可达80％以上，而使用对比例中电解液的电池仅循环54周就出现容量跳水现象。这是由于实施例1的电解液在电池正极表面生成的高电位稳定的CEI膜，在金属锂负极表面生成高界面稳定性的SEI膜，可有效抑制锂金属二次电池在长寿命循环过程中正极过渡金属溶出带来的副反应，和抑制由于金属锂粉化产生的体积膨胀，有效提高电池的容量保持率，提升电池的循环稳定性。Comparison of cycle capacity retention rate of lithium metal secondary batteries: As can be seen from Figure 2, under the same charge and discharge regime, Example 1 has better cycle stability than the battery using the comparative electrolyte, and the life performance of lithium metal secondary batteries is improved to a certain extent through the optimization of the electrolyte. The battery using the electrolyte of Example 1 can still maintain a capacity retention rate of more than 80% after 155 weeks of stable circulation in a lean liquid state, while the battery using the electrolyte in the comparative example has a capacity dive after only 54 cycles. This is because the electrolyte of Example 1 generates a high-potential stable CEI film on the surface of the positive electrode of the battery, and generates a SEI film with high interface stability on the surface of the metal lithium negative electrode, which can effectively inhibit the side reactions caused by the dissolution of the positive transition metal during the long-life cycle of the lithium metal secondary battery, and inhibit the volume expansion caused by the powdering of the metal lithium, effectively improving the capacity retention rate of the battery and improving the cycle stability of the battery.
综合上述可知，与现有技术相比较，本发明提供的提升锂金属二次电池倍率性能的电解液，对提升锂金属二次电池正、负极界面稳定性和降低锂金属二次电池放电内阻具有明显效果，可有效提高锂金属二次电池的循环稳定性；本发明提供的锂金属二次电池用的高功率电解液的制备方法及锂金属二次电池，在锂金属二次电池的实际应用中提供可工程化方案，大幅度提高锂金属二次电池的整体性能，有利于提高电池的市场应用前景，具有重大的生产实践意义。应当理解的是，本发明的上述具体实施方式仅仅用于示例性说明或解释本发明的原理，而不构成对本发明的限制。因此，在不偏离本发明的精神和范围的情况下所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。此外，本发明所附权利要求旨在涵盖落入所述权利要求范围和边界、或者这种范围和边界的等同形式内的全部变化和修改例。In summary, it can be seen that compared with the prior art, the electrolyte provided by the present invention for improving the rate performance of lithium metal secondary batteries has obvious effects on improving the interface stability of the positive and negative electrodes of lithium metal secondary batteries and reducing the discharge internal resistance of lithium metal secondary batteries, and can effectively improve the cycle stability of lithium metal secondary batteries; the preparation method of the high-power electrolyte for lithium metal secondary batteries and the lithium metal secondary battery provided by the present invention provide an engineering solution in the practical application of lithium metal secondary batteries, greatly improve the overall performance of lithium metal secondary batteries, and are conducive to improving the market application prospects of batteries, and have great production and practical significance. It should be understood that the above-mentioned specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the scope of protection of the present invention. In addition, the claims attached to the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the claims, or the equivalent forms of such scopes and boundaries.
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| CN118825413A (en)* | 2024-09-18 | 2024-10-22 | 欣界能源科技(江苏)有限公司 | Electrolyte for lithium metal battery, lithium metal battery and recycling method thereof |
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| CN118825413A (en)* | 2024-09-18 | 2024-10-22 | 欣界能源科技(江苏)有限公司 | Electrolyte for lithium metal battery, lithium metal battery and recycling method thereof |
| CN118825413B (en)* | 2024-09-18 | 2024-12-27 | 欣界能源科技(江苏)有限公司 | Electrolyte for lithium metal battery, lithium metal battery and recycling method thereof |
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