WO2018000493A1 - 一种锂-二硫化铁电池 - Google Patents

一种锂-二硫化铁电池 Download PDF

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WO2018000493A1
WO2018000493A1 PCT/CN2016/091882 CN2016091882W WO2018000493A1 WO 2018000493 A1 WO2018000493 A1 WO 2018000493A1 CN 2016091882 W CN2016091882 W CN 2016091882W WO 2018000493 A1 WO2018000493 A1 WO 2018000493A1
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lithium
mol
battery
electrolyte
iron disulfide
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PCT/CN2016/091882
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English (en)
French (fr)
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谭光平
石桥
赵宝顺
李兆鹏
陈燃
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深圳新宙邦科技股份有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M6/00—Primary cells; Manufacture thereof
    • H01M6/14—Cells with non-aqueous electrolyte
    • H01M6/16—Cells with non-aqueous electrolyte with organic electrolyte

Definitions

  • the invention relates to the technical field of lithium primary batteries, in particular to a lithium-iron disulfide battery and a lithium-iron disulfide battery non-aqueous electrolyte comprising a disulfide (FeS 2 ) cathode material.
  • a lithium-iron disulfide battery and a lithium-iron disulfide battery non-aqueous electrolyte comprising a disulfide (FeS 2 ) cathode material.
  • Lithium primary battery also known as primary lithium battery
  • primary lithium battery has high output capacity, low self-discharge rate (can be stored at room temperature for 5 to 10 years), smooth discharge, good standardization of model, and so on.
  • the increase has been rapidly evolving, and in today's consumer-driven device market, it is preferred to standardize the size of a primary lithium battery (such as AA or AAA) and a specific rated voltage (typically 1.5V).
  • a lithium battery specifically for 1.5V consumer equipment is a lithium-iron disulfide (or Li/FeS 2 ) battery having an IEC standard for AA size and an FR03 standard for AAA size.
  • the anode of the lithium iron battery is iron disulfide (FeS 2 ), and the negative electrode is lithium metal (Li).
  • the discharge reaction mechanism of the battery is: FeS 2 +4Li ⁇ Fe+2Li 2 S, and the theoretical gram capacity of FeS 2 is 893.6 mAh/
  • the theoretical gram capacity of g, Li is 3861.4 mAh/g, and its theoretical specific energy is as high as 1323 Wh/kg.
  • the theoretical specific energy of other commonly used lithium manganese, alkali manganese, zinc oxidized silver and other disposable batteries is only 200-500 Wh/kg. . Therefore, lithium iron batteries have great advantages compared with other disposable batteries such as lithium manganese, alkali manganese, zinc silver oxide, and are new disposable batteries that will rapidly develop in the future.
  • the lithium metal of the lithium iron battery anode reacts violently with water, which determines that the electrolyte in the lithium/iron disulfide battery system usually uses a non-aqueous organic solvent.
  • non-aqueous organic solvents include: glycol ethers, pentylene rings, cyclic carbonates, butyrolactones, and phosphates. These organic solvents do not react violently with metallic lithium.
  • a passivation film is formed at the interface where the metallic lithium contacts the solvent.
  • This passivation film is often electrically insulated and ion-insulated, affecting the migration of conductive ions in the battery, thereby increasing the internal resistance and hysteresis voltage of the battery, and reducing the discharge voltage and discharge capacity of the battery.
  • the formation of the passivation film causes a large voltage drop and a large capacity loss during discharge.
  • the capacity loss caused by a lithium-iron battery during long-term storage has the following aspects: First, as described above, the negative passivation film is continuously thickened during storage to cause an increase in internal resistance, and the second is inside the battery during storage. The occurrence of micro-short circuit, the third is the use of high-activity ethers such as dioxolane to polymerize during storage causes the electrolyte to become sticky, lithium ion migration becomes slower, and internal resistance increases.
  • Chinese patent CN101485016B proposes that adding iodine to the electrolyte can weaken the formation of the passivation layer on the lithium negative electrode to reduce or inhibit the passivation rate of the lithium negative electrode;
  • CN101689643A proposes to add a small amount of pyridine to the electrolyte to reduce the chance of polymerization of dioxolane. , thereby improving the battery to cause long-term storage of the polymerization of the electrolyte to cause an increase in internal resistance;
  • 6,849,360 B2 describes that the electrolyte includes lithium iodide, dioxolane, ethylene glycol dimethyl ether and a small amount of 3,5-dimethyl Isooxazolyl, in which a small amount of 3,5-dimethylisoxazole is added to ensure long-term stability of the electrolyte.
  • Fe 2+ on the positive electrode is always released, and will go down to the negative electrode to be reduced to Fe, thereby impairing the positive active material FeS 2 and reducing the discharge capacity of the battery.
  • lithium iron battery electrolyte which can dissociate lithium ions and be solvated, and is stable to both the positive and negative electrodes of the lithium iron battery during long-term storage, thereby ensuring long life of the lithium iron battery.
  • the present invention provides a lithium-iron disulfide battery which improves the storage life and discharge capacity of a battery, and a use of a non-aqueous electrolyte containing LiFSI in a lithium-iron disulfide battery.
  • a lithium-iron disulfide battery comprising iron disulfide (FeS 2 ) as a positive electrode, lithium or a lithium alloy as a negative electrode, and between the above positive electrode and negative electrode
  • the separator further includes a nonaqueous electrolyte, and the nonaqueous electrolyte includes a nonaqueous organic solvent and an electrolyte salt, and the electrolyte salt includes at least lithium bisfluorosulfonimide (LiFSI).
  • the total concentration of the electrolyte salt is 0.5 to 2.0 mol/L.
  • the concentration of the lithium bisfluorosulfonimide is 0.1 to 1.5 mol/L.
  • the total concentration of the electrolyte salt is 0.75 to 1.0 mol/L, and the concentration of the lithium bisfluorosulfonimide is 0.2 to 0.8 mol/L.
  • the above electrolyte salt further includes lithium iodide.
  • the molar concentration of the lithium iodide in the nonaqueous electrolytic solution is 1.0 mol/L or less.
  • the total concentration of the electrolyte salt is 0.75 to 1.0 mol/L
  • the molar concentration of the lithium bisfluorosulfonimide is 0.2 to 0.8 mol/L.
  • the molar concentration of lithium iodide is 0.2 to 0.8 mol/L.
  • the non-aqueous organic solvent is selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate.
  • PC propylene carbonate
  • EC ethylene carbonate
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • GBL ⁇ -butyrolactone
  • SL sulfolane
  • DMSO dimethyl sulfoxide
  • DOL dioxolane
  • THF tetrahydrofuran
  • 2-MeTHF 2-methyltetrahydrofuran
  • DME ethylene glycol dimethyl ether
  • DG diethylene glycol dimethyl ether
  • tetraethylene glycol dimethyl ether triethylene glycol dimethyl ether
  • the non-aqueous electrolyte further comprises 0.01% to 2% of an additive, and the additive is selected from a nitrogen-containing organic base; and preferably, the nitrogen-containing organic substance is used.
  • the base is at least one selected from the group consisting of 3,5-dimethylisoxazole (DMI), pyridine (BD), tri-n-butylamine, triethylamine, and t-butylamine.
  • a nonaqueous electrolytic solution comprising a nonaqueous organic solvent and comprising at least lithium difluorosulfonimide as an electrolyte salt in the preparation of a lithium-iron disulfide battery.
  • the total concentration of the electrolyte salt is 0.5 to 2.0 mol/L, and the concentration of the lithium bisfluorosulfonimide is 0.1 to 1.5 mol/L; more preferably, the above nonaqueous In the electrolytic solution, the total concentration of the above electrolyte salt is 0.75 to 1.0 mol/L, and the concentration of the lithium bisfluorosulfonimide is 0.2 to 0.8 mol/L.
  • LiFSI Lithium difluorosulfonimide lithium
  • LiFSI forms a protective film on the positive electrode of the lithium iron battery, thereby effectively suppressing the elution of Fe 2+ on the positive electrode.
  • the composition of the negative passivation film is changed, and the stability of the negative passivation film is improved, thereby suppressing the occurrence of internal micro short circuit of the lithium iron battery during storage, and improving the storage life and discharge capacity of the battery.
  • the present invention has been made by the inventors based on the use of lithium bisfluorosulfonimide (LiFSI) in an electrolyte of a lithium-iron disulfide battery, which can effectively suppress the elution of Fe 2+ on the positive electrode.
  • LiFSI lithium bisfluorosulfonimide
  • the lithium-iron disulfide battery provided by the present invention includes iron disulfide (FeS 2 ) as a positive electrode, lithium or a lithium alloy as a negative electrode, and a separator interposed between the above positive electrode and negative electrode, and includes non-aqueous
  • the electrolyte solution, the non-aqueous electrolyte solution includes a non-aqueous organic solvent and an electrolyte salt, and the electrolyte salt includes at least lithium difluorosulfonimide (LiFSI).
  • Controlling the total concentration of the electrolyte salt and the LiFSI concentration in the non-aqueous electrolyte has a certain influence on the storage life and discharge capacity of the lithium-iron disulfide battery and the inhibition of the dissolution of Fe 2+ on the positive electrode.
  • the total concentration of the electrolyte salt in the nonaqueous electrolytic solution is 0.5 to 2.0 mol/L; preferably, in the nonaqueous electrolytic solution, the concentration of lithium bisfluorosulfonimide is 0.1. ⁇ 1.5mol/L. More preferably, in the nonaqueous electrolytic solution, the total concentration of the electrolyte salt is 0.75 to 1.0 mol/L, and the concentration of lithium bisfluorosulfonimide is 0.2 to 0.8 mol/L.
  • the electrolyte salt in the nonaqueous electrolytic solution may further include other lithium salts such as lithium iodide.
  • the molar concentration of lithium iodide in the non-aqueous electrolyte is 1.0 mol/L or less, which may contain a relatively appropriate amount of lithium bisfluorosulfonimide, and does not cause the total concentration of the electrolyte salt to exceed the upper limit. The effect of suppressing the elution of Fe 2+ on the positive electrode can be exhibited well, and the storage life and discharge capacity can be effectively improved.
  • the total concentration of the electrolyte salt in the nonaqueous electrolytic solution is 0.75 to 1.0 mol/L, and the molar concentration of lithium bisfluorosulfonimide is 0.2 to 0.8 mol/L, and the molar concentration of lithium iodide is 0.2 to 0.8 mol/L.
  • the non-aqueous organic solvent may be selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ⁇ . - Butyrolactone (GBL), sulfolane (SL), dimethyl sulfoxide (DMSO), dioxolane (DOL), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), ethylene glycol At least two of ether (DME), diethylene glycol dimethyl ether (DG), triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether.
  • PC propylene carbonate
  • EC ethylene carbonate
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • GBL ⁇ . - Butyrolactone
  • SL sulfolane
  • an additive may be further included in the nonaqueous electrolytic solution, and a suitable additive is selected from a nitrogen-containing organic base; preferably, a nitrogen-containing element.
  • the organic base is at least one selected from the group consisting of 3,5-dimethylisoxazole (DMI), pyridine (BD), tri-n-butylamine, triethylamine, and t-butylamine.
  • LiFSI Lithium difluorosulfonimide lithium
  • LiFSI forms a protective film on the positive electrode of the lithium iron battery, thereby effectively suppressing the elution of Fe 2+ on the positive electrode.
  • the composition of the negative passivation film is changed, and the stability of the negative passivation film is improved, thereby suppressing the occurrence of internal micro short circuit of the lithium iron battery during storage, and improving the storage life and discharge capacity of the battery.
  • lithium bisfluorosulfonimide concentration is 0.1mol/L
  • lithium iodide concentration is 0.4mol/L
  • a small amount of additive DMI is added to prepare the non-aqueous electrolyte of the primary lithium iron battery of the present embodiment.
  • the primary lithium iron battery non-aqueous electrolyte of the present example was prepared by using DME and DOL as a solvent, a lithium bisfluorosulfonimide concentration of 0.5 mol/L, and a small amount of additive DMI.
  • the primary lithium iron battery non-aqueous electrolyte of the present example was prepared by using DME and DOL as a solvent, a lithium bisfluorosulfonimide concentration of 1.5 mol/L, and a small amount of additive DMI.
  • lithium bisfluorosulfonimide concentration is 0.2mol/L
  • lithium iodide concentration is 0.8mol/L
  • a small amount of additive DMI is added to prepare the non-aqueous electrolyte of the primary lithium iron battery of the present embodiment.
  • lithium bisfluorosulfonimide concentration of 0.8 mol / L lithium bisfluorosulfonimide concentration of 0.8 mol / L
  • lithium iodide concentration of 0.2 mol / L adding a small amount of additive BD, preparing a non-aqueous electrolyte of the lithium iron battery of the present embodiment .
  • the primary lithium iron battery non-aqueous electrolyte of the present example was prepared by using EC, PC and DME as a solvent and a total concentration of lithium bisfluorosulfonimide of 0.75 mol/L.
  • the concentration of lithium bisfluorosulfonimide is 0.2mol/L
  • the concentration of lithium iodide is 0.2mol/L
  • a small amount of additive DMI is added to prepare the non-aqueous electrolyte of the primary lithium iron battery of this comparative example.
  • a non-aqueous electrolyte of a primary lithium iron battery of the present comparative example was prepared by using DME and DOL as a solvent, a lithium bisfluorosulfonimide concentration of 2.5 mol/L, and a small amount of additive DMI.
  • a non-aqueous electrolyte of a primary lithium iron battery of the present comparative example was prepared by using DME and DOL as a solvent, lithium iodide 0.5 mol/L, and a small amount of additive DMI.
  • Preparation of primary lithium iron battery firstly, iron disulfide positive electrode powder, binder polyvinylidene fluoride (PVDF761), conductive additive carbon black and graphite, added to organic solvent N,N-dimethylpyrrolidone (NMP) and stirred until uniform
  • NMP organic solvent N,N-dimethylpyrrolidone
  • the dispersed positive electrode active material slurry was coated on an aluminum foil, and rolled and pressed into a positive electrode sheet of a desired button type 2032 battery. After the positive electrode sheet is dried and completely removed from the water, the negative electrode metal lithium, the porous separator film separating the positive and negative electrodes and the positive electrode sheet are respectively placed in the battery case, and the relative humidity is less than 3%.
  • the electrolyte solution prepared in the above examples and the comparative examples was injected and sealed.
  • Table 1 is a performance comparison table of Examples 1-7 and Comparative Examples 1-4.
  • the total concentration of lithium salt is controlled to 0.5-2.0 mol/L, LiFSI is 0.1-1.5 mol/L, Fe 2+ on the positive electrode of lithium-iron battery is less, and the discharge capacity of the battery after long-term storage. It is close to the discharge capacity of the battery without long-term storage, indicating that the proper amount of LiFSI can improve the stability of the positive electrode of the battery, so that the self-discharge of the battery is reduced after long-term storage, and the discharge performance of the battery is improved; the lithium salt concentration is less than 0.5 mol.
  • the primary nonaqueous electrolyte lithium iron battery provided by the present invention has the advantages of excellent discharge performance and high stability.
  • LiFSI application on lithium-disulfide primary batteries
  • LiFSI applications on primary lithium manganese batteries and lithium manganate secondary batteries are listed below.
  • a non-aqueous electrolyte of a primary lithium manganese battery of this comparative example was prepared using PC, DME and DOL as a solvent, LiFSI 1 mol/L.
  • a non-aqueous electrolyte of a primary lithium manganese battery of the present comparative ratio was prepared by using PC, DME and DOL as a solvent, LiFSI 0.5 mol/L, and LiClO 4 0.5 mol/L.
  • a non-aqueous electrolyte of a primary lithium manganese battery of this comparative example was prepared using PC, DME and DOL as a solvent, LiClO 4 1 mol/L.
  • the preparation and performance test of the primary lithium manganese battery is similar to the preparation and performance test of the above-mentioned lithium iron battery, except that the iron disulfide positive electrode powder is substituted for the iron disulfide positive electrode powder.
  • the test results are shown in Table 2.
  • a non-aqueous electrolyte of a lithium manganate secondary battery of the present comparative example was prepared using EC, EMC, and DEC as a solvent, LiFSI 0.1 mol/L, and LiPF 6 0.9 mol/L.
  • a non-aqueous electrolyte of a lithium manganate secondary battery of the present comparative example was prepared using EC, EMC and DEC as a solvent, LiPF 6 1.0 mol/L.
  • the performance test results are shown in Table 3.

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Abstract

本发明公开了一种锂-二硫化铁电池，包括作为正极的二硫化铁（FeS2）、作为负极的锂或锂合金、以及介于所述正极和负极之间的隔板，还包括非水电解液，所述非水电解液包括非水有机溶剂和电解质盐，所述电解质盐至少包括双氟代磺酰亚胺锂（LiFSI）。本发明使用LiFSI，在锂铁电池正极形成一层保护膜，有效地抑制正极上Fe2+的溶出，并且改变了负极钝化膜的成分，提高负极钝化膜的稳定性，因此抑制了锂铁电池在储存过程中内部微短路的发生，提高了电池的储存寿命和放电容量。

Description

一种锂-二硫化铁电池 技术领域
本发明涉及锂原电池技术领域，尤其涉及包含二硫化铁(FeS2)阴极材料的锂-二硫化铁电池和锂-二硫化铁电池非水电解液。
背景技术
锂原电池，也就是一次锂电池，因其一次容量高、自放电率极低(可常温存放5～10年)、放电平缓、型号标准化通用性好等优点，在近几年因市场需求不断增大得到了飞速发展，在当今的消费驱动型的设备市场中，优选的是标准化的一次锂电池的尺寸(例如AA或AAA)和特定的额定电压(通常为1.5V)。一种特别用于1.5V消费型设备的锂电池是锂-二硫化铁(或Li/FeS2)电池，对于AA尺寸具有IEC标准，对于AAA尺寸具有FR03标准。
锂铁电池的正极为二硫化铁(FeS2)，负极为金属锂(Li)，电池的放电反应机理是：FeS2+4Li→Fe+2Li2S，FeS2的理论克容量为893.6mAh/g，Li的理论克容量为3861.4mAh/g，其理论比能量高达1323Wh/kg，而常用的锂锰、碱锰、锌氧化银等其它一次性电池的理论比能量仅为200～500Wh/kg。因此，锂铁电池与锂锰、碱锰、锌氧化银等其它一次性电池相比具有非常大的优势，是未来将快速发展的新型一次性电池。
锂铁电池负极的金属锂遇水会发生剧烈反应，决定了锂/二硫化铁电池体系中其电解液通常都采用非水有机溶剂。此类非水有机溶剂包括：乙二醇醚、环氧戊环、环状碳酸酯、丁内酯以及磷酸酯等。这些有机溶剂不会与金属锂发生剧烈反应。但是由于金属锂的电位比这些溶剂低，且金属锂非常活泼，再加上溶剂中杂质以及微量水的存在，致使金属锂与溶剂接触的界面会形成一层钝化膜。这层钝化膜往往电绝缘且离子绝缘，影响电池内导电离子的迁移，从而增大电池的内阻和滞后电压，降低电池放电电压和放电容量。钝化膜的形成造成放电过程中电池电压降大、容量损失严重。
一次锂铁电池在长期储存过程中引起容量损失有以下几个方面：一是如上所说的在储存过程中负极钝化膜不断生成变厚导致内阻增大，二是在储存过程中电池内部发生微短路，三是使用二氧戊环等高活性醚类在储存过程中发生聚 合导致电解液变粘，锂离子迁移变慢，内阻增大。中国专利CN101485016B提出在电解液中添加碘可在锂负极上削弱钝化层的形成而降低或抑制锂负极钝化速率；CN101689643A提出在电解液中添加少量的吡啶以降低二氧戊环聚合的机会，从而改善电池在长期储存电解质发生聚合导致内阻增大的情况；美国专利US6849360B2中描述了电解质包括碘化锂、二氧戊环、乙二醇二甲醚及少量的3,5-二甲基异恶唑，其中添加了少量的3,5-二甲基异恶唑以保证电解质的长期稳定。但是，在电池储存过程中，正极上的Fe2+总会游离出来，并且会跑到负极上被还原成Fe，从而损害了正极活性材料FeS2降低了电池放电容量。
因此，需要一种锂铁电池电解质，可解离出锂离子并且溶剂化，并且在长期储存过程中对锂铁电池正负极都稳定，从而确保锂铁电池储存长寿命。
发明内容
研究发现，在锂-二硫化铁电池的电解液中使用双氟代磺酰亚胺锂(LiFSI)，能够有效地抑制正极上Fe2+的溶出。因此，本发明提供一种提高电池的储存寿命和放电容量的锂-二硫化铁电池，以及含有LiFSI的非水电解液在锂-二硫化铁电池中的用途。
根据本发明的第一方面，本发明提供一种锂-二硫化铁电池，包括作为正极的二硫化铁(FeS2)、作为负极的锂或锂合金、以及介于上述正极和负极之间的隔板，还包括非水电解液，上述非水电解液包括非水有机溶剂和电解质盐，上述电解质盐至少包括双氟代磺酰亚胺锂(LiFSI)。
作为本发明的进一步改进的方案，上述非水电解液中，上述电解质盐的总浓度为0.5～2.0mol/L。
作为本发明的进一步改进的方案，上述非水电解液中，上述双氟代磺酰亚胺锂的浓度为0.1～1.5mol/L。
作为本发明的进一步改进的方案，上述非水电解液中，上述电解质盐的总浓度为0.75～1.0mol/L，上述双氟代磺酰亚胺锂的浓度为0.2～0.8mol/L。
作为本发明的进一步改进的方案，上述电解质盐还包括碘化锂。
作为本发明的进一步改进的方案，上述碘化锂在上述非水电解液中的摩尔浓度为1.0mol/L以下。
作为本发明的进一步改进的方案，上述非水电解液中，上述电解质盐的总浓度为0.75～1.0mol/L，上述双氟代磺酰亚胺锂的摩尔浓度为0.2～0.8mol/L，上 述碘化锂的摩尔浓度为0.2～0.8mol/L。
作为本发明的进一步改进的方案，上述非水有机溶剂选自碳酸丙烯酯(PC)、碳酸乙烯酯(EC)、碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、γ-丁内酯(GBL)、环丁砜(SL)、二甲亚砜(DMSO)、二氧戊环(DOL)、四氢呋喃(THF)、2-甲基四氢呋喃(2-MeTHF)、乙二醇二甲醚(DME)、二乙二醇二甲醚(DG)、三乙二醇二甲醚、四乙二醇二甲醚中的至少两种。
作为本发明的进一步改进的方案，以电解液总质量计，上述非水电解液中还包括0.01％～2％的添加剂，上述添加剂选自含氮元素有机碱；优选地，上述含氮元素有机碱选自3,5-二甲基异恶唑(DMI)、吡啶(BD)、三正丁胺、三乙胺、叔丁胺中的至少一种。
根据本发明的第二方面，本发明提供一种包括非水有机溶剂并且至少包括双氟代磺酰亚胺锂作为电解质盐的非水电解液在制备锂-二硫化铁电池中的用途。优选地，上述非水电解液中，上述电解质盐的总浓度为0.5～2.0mol/L，上述双氟代磺酰亚胺锂的浓度为0.1～1.5mol/L；进一步优选地，上述非水电解液中，上述电解质盐的总浓度为0.75～1.0mol/L，上述双氟代磺酰亚胺锂的浓度为0.2～0.8mol/L。
本发明的锂-二硫化铁电池的电解液中使用了双氟代磺酰亚胺锂(LiFSI)，LiFSI在锂铁电池正极形成一层保护膜，有效地抑制正极上Fe2+的溶出，并且改变了负极钝化膜的成分，提高负极钝化膜的稳定性，因此抑制了锂铁电池在储存过程中内部微短路的发生，提高了电池的储存寿命和放电容量。
具体实施方式
为详细说明本发明的技术内容、所实现目的及效果，以下结合实施方式予以说明。
本发明是发明人基于在锂-二硫化铁电池的电解液中使用双氟代磺酰亚胺锂(LiFSI)，能够有效地抑制正极上Fe2+的溶出，这一发现做出的。因此，本发明提供的锂-二硫化铁电池，包括作为正极的二硫化铁(FeS2)、作为负极的锂或锂合金、以及介于上述正极和负极之间的隔板，还包括非水电解液，上述非水电解液包括非水有机溶剂和电解质盐，上述电解质盐至少包括双氟代磺酰亚胺锂(LiFSI)。
控制非水电解液中电解质盐的总浓度和LiFSI浓度，对于锂-二硫化铁电池的储存寿命和放电容量以及抑制正极上Fe2+的溶出有一定影响。一般而言，LiFSI浓度过低(例如，低于0.1mol/L)时，则在正极上形成有效的保护膜而抑制正极上Fe2+溶出的效果欠佳，从而保护正极的效果欠佳；而高于1.5mol/L时，虽然抑制正极上Fe2+的溶出效果优异，但是电池内阻过高，影响储存寿命和放电容量。电解质盐的总浓度小于0.5mol/L时，电解液锂离子迁移数小，即使电池长时间储存稳定，但是放电性能欠佳；电解质盐的总浓度大于2.0mol/L时，电解液粘度过大，锂离子迁移速率慢，因此同样放电性能欠佳。因此，在本发明优选的实施方案中，非水电解液中电解质盐的总浓度为0.5～2.0mol/L；优选地，非水电解液中，双氟代磺酰亚胺锂的浓度为0.1～1.5mol/L。更优选地，在非水电解液中，电解质盐的总浓度为0.75～1.0mol/L，双氟代磺酰亚胺锂的浓度为0.2～0.8mol/L。
本发明中，非水电解液中的电解质盐还可以包括碘化锂等其他锂盐。优选地，碘化锂在非水电解液中的摩尔浓度为1.0mol/L以下，这样可以含有比较适量的双氟代磺酰亚胺锂，也不会导致电解质盐的总浓度超过其上限，能够较好地发挥其抑制正极上Fe2+的溶出的效果，并且有效提高储存寿命和放电容量。在含有碘化锂的情况下，本发明的一个最优选的实施方案，非水电解液中，电解质盐的总浓度为0.75～1.0mol/L，双氟代磺酰亚胺锂的摩尔浓度为0.2～0.8mol/L，碘化锂的摩尔浓度为0.2～0.8mol/L。
本发明中，非水有机溶剂可以选自碳酸丙烯酯(PC)、碳酸乙烯酯(EC)、碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、γ-丁内酯(GBL)、环丁砜(SL)、二甲亚砜(DMSO)、二氧戊环(DOL)、四氢呋喃(THF)、2-甲基四氢呋喃(2-MeTHF)、乙二醇二甲醚(DME)、二乙二醇二甲醚(DG)、三乙二醇二甲醚、四乙二醇二甲醚中的至少两种。这些非水有机溶剂可以两两任意组合，或者三者以上任意组合使用，并且其比例没有严格限制。
在本发明更优选的实施方案中，以电解液总质量计，非水电解液中还可以包括0.01％～2％的添加剂，合适的添加剂选自含氮元素有机碱；优选地，含氮元素有机碱选自3,5-二甲基异恶唑(DMI)、吡啶(BD)、三正丁胺、三乙胺、叔丁胺中的至少一种。这些添加剂能够赋予电解液各自优异的性能，尤其是添 加3,5-二甲基异恶唑能够保证电解质的长期稳定。
本发明的锂-二硫化铁电池的电解液中使用了双氟代磺酰亚胺锂(LiFSI)，LiFSI在锂铁电池正极形成一层保护膜，有效地抑制正极上Fe2+的溶出，并且改变了负极钝化膜的成分，提高负极钝化膜的稳定性，因此抑制了锂铁电池在储存过程中内部微短路的发生，提高了电池的储存寿命和放电容量。
以下通过具体实施例对本发明进行详细描述。应当理解，这些实施例仅是示例性的，并不构成对本发明保护范围的限制。
实施例1：
使用DME和DOL作溶剂，双氟磺酰亚胺锂浓度为0.1mol/L，碘化锂浓度为0.4mol/L，加入少量的添加剂DMI，制备本实施例的一次锂铁电池非水电解液。
实施例2：
使用DME和DOL作溶剂，双氟磺酰亚胺锂浓度为0.5mol/L，加入少量的添加剂DMI，制备本实施例的一次锂铁电池非水电解液。
实施例3：
使用DME和DOL作溶剂，双氟磺酰亚胺锂浓度为1.0mol/L，碘化锂浓度为1.0mol/L，加入少量的添加剂DMI，制备本实施例的一次锂铁电池非水电解液。
实施例4：
使用DME和DOL作溶剂，双氟磺酰亚胺锂浓度为1.5mol/L，加入少量的添加剂DMI，制备本实施例的一次锂铁电池非水电解液。
实施例5：
使用DME和DOL作溶剂，双氟磺酰亚胺锂浓度为0.2mol/L，碘化锂浓度为0.8mol/L，加入少量的添加剂DMI，制备本实施例的一次锂铁电池非水电解液。
实施例6：
使用DME和DOL作溶剂，双氟磺酰亚胺锂浓度为0.8mol/L，碘化锂浓度为0.2mol/L，加入少量的添加剂BD，制备本实施例的一次锂铁电池非水电解液。
实施例7：
使用EC、PC和DME作溶剂，双氟磺酰亚胺锂总浓度为0.75mol/L，制备本实施例的一次锂铁电池非水电解液。
实施例8：
使用DME和DOL作溶剂，双氟磺酰亚胺锂浓度为0.2mol/L，碘化锂浓度为0.2mol/L，加入少量的添加剂DMI，制备本对比例的一次锂铁电池非水电解液。
实施例9：
使用DME和DOL作溶剂，双氟磺酰亚胺锂浓度为2.5mol/L，加入少量的添加剂DMI，制备本对比例的一次锂铁电池非水电解液。
对比例1：
使用DME和DOL作溶剂，碘化锂0.5mol/L，加入少量的添加剂DMI，制备本对比例的一次锂铁电池非水电解液。
性能测试：
一次锂铁电池的制备：首先将二硫化铁正极粉末、粘结剂聚偏氟乙烯(PVDF761)，导电添加剂碳黑和石墨，加入有机溶剂N，N-二甲基吡咯烷酮(NMP)搅拌至均匀，将分散好的正极活性物质浆料涂覆在铝箔上，碾压后冲压为所需的扣式2032电池的正极片。正极片通过干燥并完全去除其中的水分后，放入相对湿度低于3％的环境下，分别把负极金属锂、起到分离正负极作用的多孔隔离膜和正极片装进电池壳内，注入上述实施例以及对比例制得的电解液后封口。
将获得的一次锂铁电池进行性能测试，测试结果如表1。表1为实施例1-7与对比例1-4的性能对比表。
表1一次锂铁电池测试性能比较
Figure PCTCN2016091882-appb-000001
Figure PCTCN2016091882-appb-000002
由表1可知，在锂盐总浓度控制为0.5～2.0mol/L，LiFSI为0.1～1.5mol/L，锂铁电池正极上的Fe2+的溶出较少，电池在长时间储存后放电容量与没有长时间储存的电池放电容量接近，说明使用了适量的LiFSI能提高电池正极的稳定性，使电池在长时间储存后自放电减少了，提高了电池的放电性能；锂盐浓度小于0.5mol/L时，电解液锂离子迁移数小，即使电池长时间储存稳定，但是放电性能会下降；锂盐浓度大于2.0mol/L时，电解液粘度过大，锂离子迁移速率慢，将导致放电性能下降。
综上所述，本发明提供的一次非水电解液锂铁电池具有放电性能出色及稳定性高的优点。
为了说明LiFSI应用在锂-二硫化铁原电池上的特殊效果，下面再列举几个LiFSI应用在一次锂锰电池和锰酸锂二次电池上的实例。
对比例2：
使用PC、DME和DOL作溶剂，LiFSI 1mol/L，制备本对比例的一次锂锰电池非水电解液。
对比例3：
使用PC、DME和DOL作溶剂，LiFSI 0.5mol/L，LiClO40.5mol/L，制备本对比例的一次锂锰电池非水电解液。
对比例4：
使用PC、DME和DOL作溶剂，LiClO4 1mol/L，制备本对比例的一次锂锰电池非水电解液。
一次锂锰电池的制备和性能测试，类似上述一次锂铁电池的制备和性能测试，不同在于：以二氧化锰正极粉末替代二硫化铁正极粉末。测试结果如表2。
表2一次锂锰电池测试性能比较
Figure PCTCN2016091882-appb-000003
由表2可知，LiFSI应用到一次锂锰电池上对正极二氧化锰没有很好的稳定效果，并且也没有能提高电池的放电性能。
对比例5：
使用EC、EMC和DEC作溶剂，LiFSI 0.1mol/L，LiPF60.9mol/L，制备本对比例的锰酸锂二次电池非水电解液。
对比例6：
使用EC、EMC和DEC作溶剂，LiPF61.0mol/L，制备本对比例的锰酸锂二 次电池非水电解液。性能测试结果如表3。
表3锰酸锂二次电池测试性能比较
Figure PCTCN2016091882-appb-000004
由表3可知，LiFSI应用到锰酸锂二次电池上可明显提高电池低温放电性能，但对正极锰酸锂并没有明显好的稳定效果。
以上内容是结合具体的实施方式对本发明所作的进一步详细说明，不能认定本发明的具体实施只局限于这些说明。对于本发明所属技术领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干简单推演或替换，都应当视为属于本发明的保护范围。

Claims (10)

  1. 一种锂-二硫化铁电池，包括作为正极的二硫化铁、作为负极的锂或锂合金、以及介于所述正极和负极之间的隔板，其特征在于，还包括非水电解液，所述非水电解液包括非水有机溶剂和电解质盐，所述电解质盐至少包括双氟代磺酰亚胺锂。
  2. 根据权利要求1所述的锂-二硫化铁电池，其特征在于，所述非水电解液中，所述电解质盐的总浓度为0.5～2.0mol/L。
  3. 根据权利要求1所述的锂-二硫化铁电池，其特征在于，所述非水电解液中，所述双氟代磺酰亚胺锂的浓度为0.1～1.5mol/L。
  4. 根据权利要求1-3任一项所述的锂-二硫化铁电池，其特征在于，所述非水电解液中，所述电解质盐的总浓度为0.75～1.0mol/L，所述双氟代磺酰亚胺锂的浓度为0.2～0.8mol/L。
  5. 根据权利要求1-3任一项所述的锂-二硫化铁电池，其特征在于，所述电解质盐还包括碘化锂。
  6. 根据权利要求5所述的锂-二硫化铁电池，其特征在于，所述碘化锂在所述非水电解液中的摩尔浓度为1.0mol/L以下。
  7. 根据权利要求5所述的锂-二硫化铁电池，其特征在于，所述非水电解液中，所述电解质盐的总浓度为0.75～1.0mol/L，所述双氟代磺酰亚胺锂的摩尔浓度为0.2～0.8mol/L，所述碘化锂的摩尔浓度为0.2～0.8mol/L。
  8. 根据权利要求1所述的锂-二硫化铁电池，其特征在于，所述非水有机溶剂选自碳酸丙烯酯、碳酸乙烯酯、碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、γ-丁内酯、环丁砜、二甲亚砜、二氧戊环、四氢呋喃、2-甲基四氢呋喃、乙二醇二甲醚、二乙二醇二甲醚、三乙二醇二甲醚、四乙二醇二甲醚中的至少两种。
  9. 根据权利要求1所述的锂-二硫化铁电池，其特征在于，以电解液总质量计，所述非水电解液中还包括0.01～2％的添加剂，所述添加剂选自含氮元素有机碱；优选地，所述含氮元素有机碱选自3,5-二甲基异恶唑、吡啶、三正丁胺、三乙胺、叔丁胺中的至少一种。
  10. 一种包括非水有机溶剂并且至少包括双氟代磺酰亚胺锂作为电解质盐的非水电解液在制备锂-二硫化铁电池中的用途。
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