Lithium ion battery

Abstract

The invention discloses a lithium ion battery which is characterized by comprising a positive electrode, a negative electrode, electrolyte and a diaphragm arranged between the positive electrode and the negative electrode, the electrolyte comprises a lithium salt, an additive and a solvent, and the additive comprises 1, 3-divinyl tetramethyl disiloxane; and the negative electrode is a lithium metal negative electrode. 1, 3-divinyltetramethyldisiloxane which is a specific linear structure molecule is used as a multifunctional additive to synchronously realize positive and negative electrode dual protection, that is, a compact CEI film is formed through preferential oxidation in a positive electrode high-voltage area to inhibit electrolyte decomposition and transition metal dissolution; meanwhile, a uniform SEI layer is constructed on the surface of the lithium metal negative electrode through reduction polymerization, so that the growth of lithium dendrites is effectively inhibited, and the first coulombic efficiency is greatly improved; si-O bonds in the molecules can also efficiently remove HF in the electrolyte, and corrosion of the positive electrode is slowed down.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium metal battery, more particularly, to a lithium ion battery. BACKGROUND

[0002] High-voltage lithium metal batteries are considered as the ultimate goal of the next generation of energy storage technology due to their extremely high energy density. However, its commercialization faces severe challenges, rooted in the fact that both lithium metal anode and high-voltage cathode have severe side reactions with electrolyte: (1) At high voltage (>4.5V), conventional carbonate-based electrolyte will undergo severe oxidative decomposition on the surface of the cathode (such as high-nickel ternary NCM), leading to unstable cathode electrolyte interface film (CEI), transition metal ion dissolution and rapid capacity decay; (2) More troublesome is that the lithium metal anode will have continuous side reactions with the electrolyte, forming an unstable and uneven solid-state electrolyte interface film (SEI), leading to uncontrollable growth of lithium dendrites, continuous consumption of active lithium and electrolyte, low coulombic efficiency, and serious safety hazards; (3) Trace amounts of water in the electrolyte will promote the hydrolysis of LiPF6 to produce HF, corrode the cathode material, and accelerate the deterioration of battery performance.

[0003] There have been attempts in the prior art to use organosilicon compounds as electrolyte additives. For example, Chinese Patent Application CN119725751A discloses an electrolyte for ternary cathode / graphite anode batteries, which uses 1,3-divinyltetramethyldisiloxane (DTMDS) in combination with lithium acetylsulfamate to improve the high-voltage performance of the battery at 4.5V-4.8V. However, this technical solution is designed entirely for a graphite anode system, and its core is to solve the compatibility problem of the cathode and the electrolyte at high voltage, but the technical problems in the graphite anode system and the lithium anode system are different. In the graphite anode system, lithium ions enter the layered structure of graphite in an orderly manner, which is an intercalation / deintercalation reaction, this process is relatively mild and reversible, and the core problem is how to protect the graphite structure itself and maintain its surface stability; while in the lithium metal anode system, lithium ions, after obtaining electrons, accumulate on the surface of the anode in the form of metal atoms in a disordered manner, which is a deposition / peeling reaction, this process is extremely destructive, and the core problem is how to control the morphology of lithium metal and inhibit its reaction with the electrolyte; and this technical solution is a combination of DTMDS and lithium acetylsulfamate, its main goal is to protect the cathode and stabilize the SEI film of the graphite anode at high voltage, and it does not involve or solve the fundamental challenges brought by the lithium metal anode, such as lithium dendrites, low lithium deposition / peeling efficiency, and severe interfacial side reactions. In addition, its combination approach also increases the complexity of the electrolyte system.

[0004] Therefore, there is an urgent need in this field for a design specifically for high-voltage lithium metal battery systems that addresses the core issues of dendrite suppression, efficiency improvement, and dynamic interface stability in lithium anode systems. Instead of complex additive formulations, a single, highly efficient, multifunctional additive can be used to simultaneously stabilize the highly active positive and negative electrode interfaces and remove harmful species, thereby truly achieving long-life cycling of high-voltage lithium metal batteries. Summary of the Invention

[0005] In view of this, the present invention aims to provide a novel electrolyte additive based on 1,3-divinyltetramethyldisiloxane (DTMDS) to solve the key interface problems existing in high-voltage (≥4.5V) lithium metal batteries. By introducing DTMDS, a linear siloxane compound with a specific structure, preferential oxidation / reduction polymerization of its vinyl groups at both ends occurs on the positive and negative electrode surfaces at high and low potentials, respectively, forming dense and stable CEI and SEI protective films in situ. This simultaneously suppresses the oxidative decomposition of the electrolyte and the dissolution of transition metals at the high-voltage positive electrode, as well as the dendrite growth and side reactions at the lithium metal negative electrode. Furthermore, the Si-O bonds in its molecule efficiently remove HF impurities from the electrolyte, mitigating corrosion of the positive electrode material. Ultimately, this significantly improves the initial coulombic efficiency, long-cycle capacity retention, and safety performance of high-voltage lithium metal batteries without significantly altering the existing electrolyte system.

[0006] One aspect of this application provides a lithium-ion battery, comprising: a positive electrode, a negative electrode, an electrolyte, and a separator disposed between the positive electrode and the negative electrode; The electrolyte includes lithium salt, additives, and solvent, wherein the additives include 1,3-divinyltetramethyldisiloxane; The negative electrode is a lithium metal negative electrode.

[0007] Optionally, the amount of 1,3-divinyltetramethyldisiloxane added to the electrolyte is 0.5%-2% of the mass of the electrolyte, based on the mass of the electrolyte.

[0008] Optionally, the amount of 1,3-divinyltetramethyldisiloxane added is independently selected from any value among 0.5%, 1%, 1.5%, 2% of the mass of the electrolyte, or any range between any two of the above points.

[0009] Optionally, the additive further includes a second additive; The second additive is selected from at least one of fluoroethylene carbonate, lithium bis(oxalate) difluorophosphate, and lithium difluorophosphate.

[0010] Optionally, in the electrolyte, the amount of the second additive is 2%-10% of the mass of the electrolyte, based on the mass of the electrolyte.

[0011] Optionally, the amount of the second additive is independently selected from any value among 2%, 5%, 8%, and 10% of the mass of the electrolyte, or any range between any two of the above points.

[0012] Optionally, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorophosphate, and lithium bis(fluorosulfonyl)imide.

[0013] Optionally, the concentration of the lithium salt in the electrolyte is: .

[0014] Optionally, the concentration of the lithium salt is independently selected from... , , , Any value in or any range between any two of the above points.

[0015] Optionally, the solvent is selected from at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0016] Optionally, the active material of the positive electrode includes a ternary material of lithium nickel cobalt manganese oxide; The general formula of the lithium nickel cobalt manganese oxide ternary material (NCM) is LiNi x Mn y Co z O2, where the values ​​of x, y, and z satisfy: x ≥ 0.6, x + y + z = 1.

[0017] Optionally, the lithium metal anode is made of lithium metal or a lithium alloy.

[0018] Optionally, the charging voltage of the lithium-ion battery is 4.5V-5.0V.

[0019] Compared with the prior art, the lithium-ion battery provided by the present invention achieves at least the following beneficial effects: The core advantage of this invention lies in the innovative use of 1,3-divinyltetramethyldisiloxane (DTMDS), a molecule with a specific linear structure, as a multifunctional additive specifically designed to address the multiple interface challenges in high-voltage lithium metal battery systems. Its positive effects are primarily manifested in: achieving dual protection for both positive and negative electrodes simultaneously through a single component. Specifically, it preferentially oxidizes in the high-voltage region of the positive electrode to form a dense CEI film, inhibiting electrolyte decomposition and transition metal dissolution. Simultaneously, it reduces and polymerizes on the surface of the lithium metal negative electrode to construct a uniform SEI layer, effectively suppressing lithium dendrite growth and significantly improving the initial coulombic efficiency. Furthermore, the Si-O bonds in its molecule can efficiently remove HF from the electrolyte, mitigating positive electrode corrosion. Ultimately, under extreme high-voltage conditions of 4.95 V, this additive enables lithium metal batteries to achieve a capacity retention rate of up to 95.6% after 500 cycles and an initial efficiency of over 85%. This performance is significantly superior to traditional solutions and is compatible with existing production processes without complex compounding. It provides a key material solution for the development of next-generation high-energy-density batteries, demonstrating significant technological advancements and application prospects.

[0020] Of course, any product implementing this invention does not need to achieve all of the technical effects described above at the same time.

[0021] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0023] Figure 1 This is a schematic diagram illustrating how DTMDS additives improve the performance of NCM / Li batteries in an embodiment of the present invention. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0025] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0026] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0027] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0029] This invention provides a multifunctional electrolyte additive for high-voltage lithium metal batteries—1,3-divinyltetramethyldisiloxane (DTMDS). This additive not only helps stabilize the positive and negative electrode interfaces of high-voltage lithium metal batteries, but also removes HF impurities from the electrolyte and inhibits the dissolution of transition metals from the positive electrode, thereby enabling safe and stable long-term cycling of high-voltage lithium metal batteries. The specific technical solution is as follows: A lithium-ion battery includes: a positive electrode, a negative electrode, an electrolyte, and a separator disposed between the positive electrode and the negative electrode; The electrolyte includes lithium salt, additives, and solvents, wherein the additives include 1,3-divinyltetramethyldisiloxane; The negative electrode is a lithium metal negative electrode.

[0030] The lithium-ion battery provided in this application is a high-voltage (≥4.5V vs. Li / Li) type. + In lithium metal batteries, 1,3-divinyltetramethyldisiloxane, as an additive, can simultaneously suppress dendrite growth and side reactions of the lithium metal anode, interfacial decomposition of the high-voltage cathode, and HF corrosion in the electrolyte.

[0031] In some embodiments, the amount of 1,3-divinyltetramethyldisiloxane added to the electrolyte is 0.5%-2% of the mass of the electrolyte.

[0032] In this embodiment of the application, using the mass of the electrolyte as the basis means using the mass of the electrolyte as the calculation basis to calculate the mass fraction of a certain component in the electrolyte, such as the additive 1,3-divinyltetramethyldisiloxane accounting for 0.5%-2% of the mass fraction of the electrolyte.

[0033] The addition amount of 1,3-divinyltetramethyldisiloxane is 0.5%-2% of the electrolyte mass, ensuring that the electrolyte contains a certain amount of multifunctional additive, which helps to build a stable CEI membrane and a uniform SEI membrane, while removing harmful HF and purifying the electrolyte environment.

[0034] In some embodiments, the additive also includes a second additive; The second additive is selected from at least one of fluoroethylene carbonate, lithium bis(oxalate) difluorophosphate, and lithium difluorophosphate.

[0035] In some embodiments, the second additive is preferably fluoroethylene carbonate.

[0036] Adding a second additive to the electrolyte further contributes to the construction of a more robust "double-layer SEI film." Taking fluoroethylene carbonate (FEC) as an example, as an additive in lithium-ion battery electrolytes, FEC preferentially forms a densely structured and higher-performance SEI film (solid electrolyte interface film) at the negative electrode during the first charge of the battery, compared to other electrolyte components. FEC primarily undergoes reduction and decomposition at the negative electrode, generating an inorganic interface layer rich in LiF. LiF possesses high interfacial energy and high Young's modulus, effectively suppressing lithium dendrite penetration. DTMDS undergoes reduction and polymerization at the negative electrode, forming an organic polymer layer that imparts good flexibility and continuity to the SEI film, accommodating the significant volume changes of lithium metal. Together, these two components construct a composite SEI film structure on the lithium metal negative electrode: a "hard inner layer (LiF) and a flexible outer layer (polymer)." This structure combines high mechanical strength and good toughness, making it more stable than any SEI film formed by a single component, thereby further improving cycle life and coulombic efficiency.

[0037] In some embodiments, the amount of the second additive added to the electrolyte is 2%-10% of the electrolyte mass, based on the electrolyte mass.

[0038] The second additive is added at 2%-10% of the electrolyte mass to ensure that the electrolyte contains a certain amount of film-forming additive, which helps to form a strong SEI inorganic layer to suppress lithium dendrite puncture.

[0039] In some embodiments, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorophosphate, and lithium bis(fluorosulfonyl)imide.

[0040] In some embodiments, the lithium salt is any one of lithium hexafluorophosphate, lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide, or a combination of lithium hexafluorophosphate and lithium bis(trifluoromethylsulfonyl)imide.

[0041] Specifically, combining LiPF6 with LiFSI (or LiTFSI) aims to leverage their respective strengths and mitigate their weaknesses, achieving functional complementarity. The core function of LiPF6 is to protect the aluminum current collector. Even with a small addition (e.g., 0.5 mol / L), LiPF6 preferentially forms a stable passivation film primarily composed of aluminum fluoride (AlF3) on the aluminum foil surface. This film acts as a "protective shield," effectively preventing subsequent... or The direct attack of anions on the aluminum foil solves the problem of aluminum foil corrosion caused by imide lithium salts. The core function of LiFSI / LiTFSI is to improve bulk and interfacial properties. As the main lithium salt or an important component, LiFSI / LiTFSI improves overall ionic conductivity, enhances battery rate performance and fast charging capability, and inhibits HF generation. Due to their inherent stability and resistance to hydrolysis, their high proportion dilutes the concentration of LiPF6, significantly reducing the acidity and HF content of the entire electrolyte system. Furthermore, they participate in the construction of high-quality interfacial films; their decomposition products synergistically with the decomposition products of additives such as DTMDS and FEC to form more stable SEI and CEI films with higher ionic conductivity at the positive and negative electrodes. The combined use of LiPF6 and LiFSI (or LiTFSI) can achieve long-term stability under ultra-high voltage, as shown in Example 3. As shown, this combination achieved a capacity retention of 95.6% at an extreme voltage of 4.95V. This is because: LiPF6 ensures that the aluminum foil does not corrode (structural stability); the high stability of LiFSI ensures that the electrolyte body has stronger oxidation resistance at high voltage; the HF removal capability of DTMDS and the low HF characteristics of LiFSI form a double insurance, which greatly protects the highly active high-nickel cathode material; it can also significantly improve the cycle efficiency of lithium metal anode. LiFSI is very conducive to forming a stable SEI film rich in LiF on the lithium metal surface. LiF is an excellent SEI component that can effectively suppress lithium dendrites. Combined with the polymer film formed by DTMDS on the anode, a robust and flexible composite SEI is constructed, thereby greatly improving the coulombic efficiency of lithium deposition / stripping (e.g., 86.0% first-time efficiency in Example 3).

[0042] In some embodiments, the concentration of lithium salt in the electrolyte is [missing information]. .

[0043] In some embodiments, the solvent is selected from at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0044] In some embodiments, the active material of the positive electrode includes a ternary material of lithium nickel cobalt manganese oxide; The general formula for lithium nickel cobalt manganese oxide ternary materials is LiNi x Mn y Co z O2, where the values ​​of x, y, and z satisfy: x ≥ 0.6, x + y + z = 1.

[0045] In some implementations, the lithium metal anode is made of metallic lithium or a lithium alloy.

[0046] In some implementations, the charging voltage of the lithium-ion battery is 4.5V-5.0V.

[0047] This application specifically relates to a method for use with high voltage (≥4.5V vs. Li / Li). + The electrolyte additive for lithium metal batteries and its application: By simultaneously suppressing dendrite growth and side reactions of lithium metal anode, interface decomposition of high-voltage cathode and HF corrosion in electrolyte, the additive comprehensively improves the cycle stability and safety of the battery. For example, under extreme high voltage conditions of 4.95V, the additive enables lithium metal batteries to achieve a capacity retention rate of up to 95.6% after 500 cycles and an initial efficiency of over 85%.

[0048] In this embodiment, a separator is also included to separate the positive and negative electrodes, prevent short circuits, and allow charged particles to pass through during charging and discharging. This application does not impose any particular limitation on the separator, as long as it achieves the purpose of this application. For example, the separator material may be, but is not limited to, a polypropylene (PP) separator.

[0049] Example 1 Electrolyte preparation: Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a mass ratio of EC:EMC = 3:7. After mixing, 1% (w / w) of 1,3-divinyltetramethyldisiloxane (DTMDS) was added and 1.0 mol / L was dissolved. -1 The desired electrolyte is prepared by stirring lithium hexafluorophosphate (LiPF6) evenly.

[0050] Example 2 The electrolyte in this embodiment differs from that in Example 1 only in the additives, which are 1% by mass of 1,3-divinyltetramethyldisiloxane (DTMDS) and 5% by mass of fluoroethylene carbonate (FEC). The remaining components, contents, and preparation methods are the same as in Example 1.

[0051] Example 3 The electrolyte in this embodiment differs from that in Example 2 only in that the lithium salt has a concentration of 0.5 mol / L. -1 Lithium bis(fluorosulfonyl)imide (LiFSI) and 0.5 mol L -1 The lithium hexafluorophosphate (LiPF6) used was the same as that used in Example 1, with the remaining components, contents and preparation methods being the same.

[0052] Comparative Example 1 The difference from Example 1 is that the electrolyte does not contain DTMDS additives.

[0053] Comparative Example 2 The difference from Example 2 is that the electrolyte does not contain DTMDS additive.

[0054] Comparative Example 3 The difference from Example 3 is that the electrolyte does not contain DTMDS additives.

[0055] Example 4 The electrolytes from Comparative Examples 1-3 and Examples 1-3 were used to prepare coin cells, and the specific preparation steps are as follows: The electrolyte prepared in the above examples / comparative examples was used in an argon glove box (H2O / O2 < 0.1 ppm). The positive electrode was made of 80 wt% NCM811, 10 wt% PVDF, and 10 wt% SP coated on aluminum foil (loading 4 mg / cm). 2 The negative electrode uses 40μm lithium foil, and it is assembled into a 2032 coin cell with a polypropylene separator.

[0056] Battery performance tests were conducted on the button batteries obtained in Example 4: At 25℃, the batteries were cycle-tested using the CT2001A model equipment and testing system from Wuhan Landian Company, with a 0.5C rate setting and a charge / discharge voltage range of 3.0V - 4.95V. The battery cycle performance test results for each embodiment are shown in Table 1.

[0057] Table 1 shows the battery cycle performance test results for each embodiment.

[0058]

[0059] As shown in Table 1, the experimental data clearly demonstrate that the DTMDS additive in this invention significantly improves the cycle stability of high-voltage lithium metal batteries. Comparative Example 1 (without additive) showed a sharp drop in capacity retention to 22.3% after 500 cycles, due to the severe decomposition of the electrolyte at high voltage leading to battery failure. In contrast, the battery with 1% DTMDS (Example 1) exhibited a significant increase in capacity retention to 91.2%, strongly demonstrating that DTMDS effectively suppresses interfacial side reactions and lithium dendrite growth through its unique mechanism of forming a stable SEI layer on the lithium metal anode surface, achieving a breakthrough in the cycle performance of lithium metal batteries. When DTMDS is used synergistically with 5% FEC and mixed lithium salts (especially LiFSI) (Example 3), the capacity retention further reaches 95.6%, achieving long-term cycle performance under ultra-high voltage. Figure 1 The mechanism of action, as illustrated, is as follows: On the positive electrode side, the C=C bonds in DTMDS undergo oxidative polymerization at voltages above 4.5V, forming a dense positive electrolyte interface (CEI) layer, effectively blocking the continuous decomposition of the electrolyte under high voltage. Simultaneously, the Si-O bonds in the molecules can remove HF generated in the electrolyte, inhibiting HF erosion of the positive electrode material and the dissolution of transition metals. On the negative electrode side, the C=C bonds in DTMDS undergo cross-linking polymerization at the reduction potential, constructing a uniform solid electrolyte interface (SEI) layer, promoting uniform lithium ion deposition, thereby eliminating lithium dendrite growth and ensuring the stability of the negative electrode interface.

[0060] In this application, a single DTMDS can solve the complex problems of lithium metal anodes. Its secret lies in its unique molecular structure, which endows it with multiple synergistic mechanisms, enabling it to be "multi-functional" and construct a high-performance SEI film at the anode interface. The complete path of DTMDS to solve the anode problem includes: (1) preferential reaction: In the early stage of battery formation, DTMDS, due to its functional group activity, preferentially undergoes reduction reaction on the lithium metal surface before the solvent and lithium salt; (2) formation of framework: Through in-situ cross-linking polymerization of C=C bonds, a uniform, continuous, and flexible organosilicon polymer network is formed as the substrate of SEI; (3) synergistic film formation: This polymer network combines with the lithium salt (producing LiF, etc.) that will inevitably decompose in the electrolyte and the decomposition products of the solvent to naturally form an organic-inorganic nanocomposite SEI film; (4) realization of function: This composite SEI film simultaneously possesses: uniformity (derived from polymerization characteristics) → guiding the uniform flow of lithium ions; flexibility (derived from Si-O-Si bonds) → adapting to volume changes; high mechanical strength (derived from embedded LiF, etc.) → Physically preventing dendrite penetration; high ionic conductivity (derived from LiF and optimized interface chemistry) → ensuring rapid charge and discharge. Therefore, DTMDS is not a simple "film-forming agent," but rather a "structure guide and key component of the SEI film." Through its unique polymerization characteristics, it guides and synergistically reacts with the decomposition products of other electrolyte components to jointly construct a high-performance composite SEI film, thus systematically solving the problems of dendrite formation, side reactions, and stability in lithium metal anodes. This is the underlying principle behind its outstanding performance as a single additive.

[0061] In addition to the significant breakthrough in cycle stability, the DTMDS-containing system also demonstrated a clear advantage in initial coulombic efficiency. The initial coulombic efficiencies of Examples 1-3 were all above 85%, an improvement of more than 6.5% compared to Comparative Example 1 (78.6%) without additives. This confirms that DTMDS can preferentially react with the solvent and lithium salt during the initial cycle of the battery, forming an effective initial interface film and significantly reducing the irreversible loss of initial active lithium. Comparative experiments further highlight the interface optimization capability of DTMDS: the initial efficiency of Comparative Example 2 (containing only 5% FEC) was 82.1%, while the initial efficiency increased to 85.6% after adding DTMDS (Example 2), demonstrating the unique value of DTMDS as a multifunctional additive. More importantly, the experimental data revealed a strong synergistic effect between DTMDS and other key components (FEC and LiFSI). The capacity retention rate (94.1%) of the DTMDS combined with FEC (Example 2) was significantly higher than that of the single FEC system (Comparative Example 2: 80.5%). The core mechanism lies in the HF removal capability of DTMDS (achieved through the reaction Si-O + 2HF → Si-F + H2O), which effectively protects the FEC from the catalytic decomposition of acidic substances in the electrolyte and maintains the film stability of the FEC itself. Similarly, DTMDS and LiFSI showed a synergistic effect in Example 3, pushing the capacity retention rate to 95.6%, which was significantly better than Comparative Example 3 (85.6%) containing only LiFSI. This is attributed to the fact that LiFSI can effectively enhance the ionic conductivity of the electrolyte, while DTMDS focuses on inhibiting the corrosion and damage to the positive electrode interface under high voltage. The two complement each other and jointly construct a more stable electrode / electrolyte interface.

[0062] As can be seen from the above embodiments, the lithium-ion battery provided by the present invention achieves at least the following beneficial effects: This invention proposes that introducing DTMDS as a multifunctional additive is a key strategy for improving the performance of high-voltage lithium metal batteries. Its unique dual-electrode mechanism, through in-situ polymerization at both the positive and negative electrodes, forms a dense CEI and a stable SEI layer, respectively. This effectively suppresses electrolyte decomposition, transition metal dissolution, and lithium dendrite growth under high voltage, thereby achieving a breakthrough improvement in cycle stability. Simultaneously, DTMDS significantly optimizes the initial coulombic efficiency (>85%) and reduces initial active lithium loss. More importantly, DTMDS exhibits a strong synergistic effect with FEC (providing protection by HF removal) and LiFSI (enhancing ion conductivity), jointly constructing a more stable electrode / electrolyte interface. These findings not only verify the superior performance of DTMDS under extreme high-voltage conditions but also provide important material design and interface engineering ideas for developing next-generation lithium metal batteries with both high energy density and long cycle life, demonstrating significant practical application prospects.

[0063] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A lithium-ion battery, characterized in that, include: A positive electrode, a negative electrode, an electrolyte, and a separator disposed between the positive electrode and the negative electrode; The electrolyte includes lithium salt, additives, and solvent, wherein the additives include 1,3-divinyltetramethyldisiloxane; The negative electrode is a lithium metal negative electrode.

2. The lithium-ion battery according to claim 1, characterized in that, In the electrolyte, the amount of 1,3-divinyltetramethyldisiloxane added is 0.5%-2% of the mass of the electrolyte, based on the mass of the electrolyte.

3. The lithium-ion battery according to claim 1, characterized in that, The additive also includes a second additive; The second additive is selected from at least one of fluoroethylene carbonate, lithium bis(oxalate) difluorophosphate, and lithium difluorophosphate.

4. The lithium-ion battery according to claim 3, characterized in that, In the electrolyte, based on the mass of the electrolyte, the amount of the second additive is 2%-10% of the mass of the electrolyte.

5. The lithium-ion battery according to claim 1, characterized in that, The lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorophosphate, and lithium bis(fluorosulfonyl)imide.

6. The lithium-ion battery according to claim 1, characterized in that, In the electrolyte, the concentration of the lithium salt is: .

7. The lithium-ion battery according to claim 1, characterized in that, The solvent is selected from at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

8. The lithium-ion battery according to claim 1, characterized in that, The active material of the positive electrode includes a ternary material of lithium nickel cobalt manganese oxide; The general formula of the lithium nickel cobalt manganese oxide ternary material is LiNi x MnyCo z O2, where the values ​​of x, y, and z satisfy: x ≥ 0.6, x + y + z = 1.

9. The lithium-ion battery according to claim 1, characterized in that, The lithium metal anode is made of metallic lithium or a lithium alloy.

10. The lithium-ion battery according to claim 1, characterized in that, The charging voltage of the lithium-ion battery is 4.5V-5.0V.

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