Electrolyte suitable for lithium-rich manganese-based material and application thereof and lithium-rich manganese-based lithium ion battery
By adding a specific ratio of carbon ester solvent and conductive lithium salt to the electrolyte, the problems of poor safety and high-rate cycle performance of lithium-rich manganese-based batteries have been solved, and the long-cycle stability and safety of the battery under high temperature and high rate conditions have been improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-07
- Publication Date
- 2026-08-04
AI Technical Summary
Existing electrolytes cannot be effectively adapted to lithium-rich manganese-based batteries, resulting in insufficient safety performance, failure to meet needle penetration safety standards, and poor high-rate cycle performance, making it difficult to meet the high standards required for power batteries and energy storage batteries.
A homogeneous solution of carbon ester solvent, Formula 1, Formula 2 and conductive lithium salt is used. By controlling the ratio of the two solutions to 6:0.5~3.5:0.5~3.5 and the molar concentration of the conductive lithium salt to 0.5~5 M, a synergistic effect is formed, which improves the compatibility of lithium-rich manganese-based materials and enhances the safety and high-rate cycle performance of the battery.
It achieves the intrinsic non-flammability of the battery, improves the safety of puncture and the long-cycle stability under high temperature and high rate, and breaks through the application barriers of lithium-rich manganese-based batteries in power batteries and energy storage batteries.
Smart Images
Figure CN122512002A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery electrolytes, specifically relating to electrolytes adapted to lithium-rich manganese-based materials and their applications, as well as the field of lithium-rich manganese-based lithium-ion batteries. Background Technology
[0002] With the rapid development of the new energy industry, increasingly stringent requirements have been placed on the energy density, safety performance, and rate performance of batteries in fields such as power batteries and energy storage batteries. Lithium-rich manganese-based cathode materials (usually represented as xLi2MnO3·(1-x)LiMO2, where M is a transition metal element such as Ni, Co, or Mn) have extremely high theoretical specific capacity (up to 250~300 mAh / g), far exceeding that of traditional cathode materials such as LiCoO2 and LiFePO4. They are considered one of the core cathode materials for next-generation high-energy-density batteries and have broad application prospects in the field of pouch batteries.
[0003] However, the industrialization of lithium-rich manganese-based pouch batteries is constrained by many technical bottlenecks, among which the performance compatibility of electrolytes is one of the key bottlenecks. Existing electrolytes generally have the following three core problems when adapting to lithium-rich manganese-based batteries, which seriously limit their practical application:
[0004] First, there are insufficient safety performance and a significant flammability risk. Currently, commercial lithium battery electrolytes are mostly based on carbonate solvents (such as ethylene carbonate EC, dimethyl carbonate DMC, etc.). These solvents are highly flammable. Once the battery is subjected to abuse such as internal short circuits, punctures, or crushing, it is extremely easy to cause electrolyte combustion, battery fire, or even explosion. Especially for pouch batteries, their outer casing sealing and impact resistance are relatively weaker than rigid batteries, making the safety hazards more prominent in abuse scenarios such as punctures. Existing electrolytes lack intrinsic non-flammability, failing to address this safety concern at its root and making it difficult to meet the high safety standards required for power batteries and energy storage batteries.
[0005] Second, the needle penetration safety performance fails to meet the standards. During charging and discharging, lithium-rich manganese-based materials undergo phenomena such as lattice distortion and oxygen release, which can easily lead to micro-short circuits inside the battery. The stability of existing electrolytes is insufficient, and under the local high temperature and short circuit environment caused by needle penetration, they will rapidly undergo oxidation and decomposition, releasing a large amount of heat and gas, further aggravating the thermal runaway of the battery. As a result, the pouch battery cannot pass the needle penetration safety test, which has become a major obstacle to the large-scale application of lithium-rich manganese-based pouch batteries.
[0006] Third, its high-rate cycle performance is poor, making it difficult to meet the needs of high-power scenarios. During high-rate (e.g., 10C and above) charge and discharge processes, lithium-rich manganese-based batteries experience severe polarization at the electrode interface. At the same time, the electrolyte has insufficient ion conduction rate and high interfacial impedance, and the electrolyte is prone to decomposition during high-rate cycling, leading to rapid capacity decay and shortened cycle life. This makes it impossible to meet the practical application requirements of high-power power batteries (such as fast-charging scenarios for new energy vehicles) and energy storage batteries.
[0007] In summary, existing technologies have disclosed some solutions. For example, patent document CN119786728A discloses a high-performance lithium-rich manganese-based lithium-ion battery electrolyte with flame-retardant function and its preparation method. However, such additive-type flame-retardant electrolytes often have limited flame-retardant efficiency and cannot achieve intrinsic non-flammability. Furthermore, the introduction of additives may reduce the ionic conductivity of the electrolyte, damage the electrode interface stability, and further deteriorate the rate performance and cycle performance of the battery. Another example is patent document CN121416612A, which discloses a high-rate performance electrolyte for lithium-rich manganese, its preparation method, and its application. Specifically, it reports an electrolyte containing 2,3-bis(trifluoromethyl)propynyl sulfate, which exhibits good performance. However, existing technologies still struggle to efficiently adapt to the physicochemical characteristics of lithium-rich manganese-based materials, making it difficult to simultaneously achieve high safety, high rate performance, and long cycle performance in lithium-rich manganese-based batteries. Summary of the Invention
[0008] To address the problems existing in the prior art, the primary objective of this invention is to provide an electrolyte for lithium-rich manganese-based lithium-ion batteries. This electrolyte is designed to meet the application requirements of lithium-rich manganese-based batteries, thereby providing higher safety and improving their high-rate cycle performance.
[0009] The second objective of this invention is to provide the application of the electrolyte in the preparation of lithium-rich manganese-based batteries and the resulting batteries.
[0010] Different cathode materials possess different physicochemical characteristics, leading to various challenges in their application. For instance, lithium-rich manganese-based materials exhibit nucleophilic oxygen radicals that can cause electrolyte decomposition during cycling, generating gases such as carbon dioxide and oxygen. These gases, when mixed with the intrinsically flammable carbonate solvent in the electrolyte, can easily cause combustion, explosion, and other safety issues. Furthermore, lithium-rich manganese-based materials are predominantly manganese, resulting in poor intrinsic conductivity and consequently, poor rate performance. These problems become even more challenging under high-temperature and high-voltage testing conditions. To address the challenges posed by lithium-rich manganese-based materials and suitable electrolytes, this invention aims to provide an electrolyte that adapts to their physicochemical characteristics, thereby enhancing battery safety and improving cycle performance at high rates. Specifically:
[0011] The electrolyte suitable for lithium-rich manganese-based materials is a homogeneous solution containing carbon ester solvents, Formula 1, Formula 2, Formula 3 and conductive lithium salts;
[0012] Formula 1;
[0013] Formula 2;
[0014] Formula 3;
[0015] In the electrolyte, the mass ratio of carbon ester solvent, Formula 1, and Formula 2 is 6:0.5~3.5:0.5~3.5; the content of Formula 3 is 1~5 wt.%; and the molar concentration of conductive lithium salt is 0.5~5 M.
[0016] Existing lithium-manganese-based lithium-ion batteries struggle to maintain good long-term cycle life under extreme conditions such as high temperature, high pressure, and high rate, and also fail the nail penetration test. To address this issue, this invention, through in-depth research, innovatively discovers that combining Formulas 1 to 3, along with specific control of the component ratios, can unexpectedly achieve synergy. This improves the compatibility of lithium-manganese-based materials, adapts to the physicochemical characteristics of lithium-manganese-based batteries, significantly enhances their safety, and makes them resistant to combustion and nail penetration tests. Furthermore, it significantly enhances the long-term cycle stability of the resulting battery under extreme conditions such as high temperature and rates up to 10C.
[0017] Carbon ester solvents include at least one of EMC (ethyl methyl carbonate), DEC (diethyl carbonate), EC (ethylene carbonate), and DMC (dimethyl carbonate).
[0018] In this invention, the combined synergy of specific structures in Formulas 1 to 3 is key to enhancing the compatibility of lithium-rich manganese-based materials and improving their resistance to needle penetration and long-cycle stability under extreme conditions such as high temperature, high pressure, and ultra-high rate.
[0019] In the electrolyte, the mass ratio of the carbon ester solvent, Formula 1, and Formula 2 is 6:0.8~1.2:2.8~3.2. Studies have shown that the preferred ratio helps to further impart intrinsic non-flammability to the electrolyte, improve the intrinsic safety of the battery, and effectively improve the high-rate performance of lithium-rich manganese-based batteries, resulting in better long-cycle performance under high voltage and high rate conditions.
[0020] The content of Formula 3 in the electrolyte is 2.5~3.5 wt.%. Studies have shown that, under the preferred ratio, better long-cycle performance under high pressure and high rate can be obtained.
[0021] The conductive lithium salt includes at least one of LiPF6, LiFSI, and LiTFSI.
[0022] The concentration of the conductive lithium salt is 1~3M; more specifically, it can be 1.1~1.5M.
[0023] The present invention also includes the application of the electrolyte, using it as an electrolyte to prepare lithium-rich manganese-based lithium-ion batteries with lithium-rich manganese-based materials as positive electrode materials.
[0024] Furthermore, the electrolyte is used to prepare lithium-rich manganese-based soft-pack lithium-ion batteries with lithium-rich manganese-based materials as the positive electrode material.
[0025] The present invention also provides a lithium-rich manganese-based lithium-ion battery, wherein the active material in the positive electrode comprises a lithium-rich manganese-based active material and contains the electrolyte described in the present invention.
[0026] In this invention, the chemical formula of the lithium-rich manganese-based active material is: Li x Mn y M z O2, wherein M includes Ni and / or Co; wherein 1 <x≤1.5;0.4≤y≤0.8;0<z <0.4;
[0027] Preferably, x is 1.1 to 1.3; the molar ratio of y / z is 1 to 3:1, and y+z equals 0.7 to 0.9;
[0028] Furthermore, the lithium-rich manganese-based active material is Li 1.2 Ni 0.267 Mn 0.533 O2, Li 1.2 Ni 0.17 Mn 0.50 Co 0.13 O2, Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O2, Li 1.17 Ni 0.17 Mn 0.5 Co 0.17 At least one of O2.
[0029] In this invention, the negative electrode of the lithium-rich manganese-based lithium-ion battery is at least one of metallic lithium, carbon material, silicon material, and silicon-carbon material.
[0030] The lithium-rich manganese-based lithium-ion battery of the present invention, except for the electrolyte described in the present invention, has other known components and structural relationships.
[0031] Beneficial effects:
[0032] This invention innovatively combines Formulas 1 to 3, along with the coordinated control of their proportions, to achieve synergistic compatibility with lithium-rich manganese-based materials. This imparts intrinsic non-flammability to the electrolyte and automatically captures oxygen free radicals generated during cycling of lithium-rich manganese-based cathode materials. Lithium-rich manganese-based batteries prepared with this electrolyte meet the nail penetration safety test standards, improving the intrinsic safety of the battery. Furthermore, it effectively enhances the high-rate performance of lithium-rich manganese-based batteries, achieving a synergistic improvement in battery safety and high-rate electrochemical performance. This fundamentally solves the industry pain points of poor compatibility between existing electrolytes and lithium-rich manganese-based cathode materials, significant safety hazards, and rapid cycle life decay at high rates. It can effectively overcome the technical barriers of lithium-rich manganese-based batteries in practical applications such as power batteries and energy storage batteries. Attached Figure Description
[0033] Figure 1 This is a long-cycle data graph of the soft-pack battery in Example 1, where the electrolyte is matched with a graphite-rich manganese-based cathode at 30°C and 4.5V.
[0034] Figure 2 This is a data graph showing the charge-discharge curves of a soft-pack battery with a graphite-rich manganese-based cathode matched with the electrolyte at 30°C and 4.5V, as described in Example 1.
[0035] Figure 3 This is a long-cycle data graph of the soft-pack battery in Example 1, where the electrolyte is matched with a graphite-rich manganese-based cathode at 45°C and 4.5V.
[0036] Figure 4 This is a graph showing the high-rate (10C) long-cycle data of a coin cell with lithium metal and a lithium-rich manganese-based cathode matched with the electrolyte of Example 1 at 30°C and 4.65V.
[0037] Figure 5 This is a graph showing the long-cycle data of a coin cell with lithium metal and a lithium-rich manganese-based cathode matched with the electrolyte of Example 1 at 30°C and 4.8V. Detailed Implementation
[0038] The electrolyte of the present invention, through the combination of components and proportions of Formulas 1 to 3, can achieve synergy, adapt to the physicochemical characteristics of lithium-rich manganese-based batteries, endow the electrolyte with intrinsic non-flammability, and effectively improve the high-rate performance of lithium-rich manganese-based batteries.
[0039] The present invention also shows that replacing Formula 1 with Comparative Formula A and Comparative Formula B, replacing Formula 2 with Comparative Formula C and Comparative Formula D, and replacing Formula 3 with Comparative Formula E and Comparative Formula F will all affect the synergy of the components and will not help solve the problems of poor safety and poor high-rate cycle performance of lithium-rich manganese-based batteries.
[0040] Comparison A;
[0041] Comparative B;
[0042] Comparative form C;
[0043] Contrast D;
[0044] Comparative E;
[0045] Contrast F;
[0046] Example 1
[0047] Electrolyte preparation: In a dry argon-atmospheric glove box, a carbon ester solvent (ethyl methyl carbonate, also known as EMC in this case), Formula 1, and Formula 2 were mixed in a mass ratio of 6:1:3. Then, conductive lithium salt (LiPF6) was added, dissolved, and stirred thoroughly. After clarification, Formula 3 was added and stirred until homogeneous to obtain the composite electrolyte. The total molar concentration of lithium salt in the composite electrolyte was 1.2 mol / L, and the mass percentage of Formula 3 in the electrolyte was 3%.
[0048] The aforementioned composite electrolyte was injected into CR2016 button and pouch batteries. The positive electrode of the button battery used a lithium-rich manganese-based positive electrode (optional, comprising active material (lithium-rich manganese-based material) in a weight ratio of 9:0.5:0.5), a binder, and a conductive agent, wherein the lithium-rich manganese-based active material was Li... 1.2 Ni 0.267 Mn 0.533 O2 (optional PVDF binder, optional acetylene black conductive agent), lithium metal anode, and Celgard 2500 separator. The positive electrode material for the pouch battery is prepared as above, and the negative electrode is a graphite anode (comprising graphite active material, binder, and conductive agent in a weight ratio of 9:0.5:0.5, wherein the graphite active material is optionally artificial graphite, the binder is optionally PVDF, and the conductive agent is optionally acetylene black). The separator material is the same as above. The preparation of the composite electrolyte and the assembly of the pouch and button batteries are carried out in an argon-filled glove box, with oxygen and moisture content below 0.5 ppm (parts per million).
[0049] The intrinsically safe lithium-rich manganese-based high-temperature, high-pressure, high-rate, long-life electrolyte obtained in this embodiment and its performance test results are shown in the figure:
[0050] Test 1: Capacity retention rate of pouch battery at 30℃ / 1C / 4.5V / 1000 cycles:
[0051] Figure 1The data from Example 1, based on a 1C long-cycle test of a soft-pack battery with a graphite-rich manganese-based cathode matched at 30°C and 4.5V, demonstrates the intrinsically safe, high-temperature, high-pressure, high-rate, long-life lithium-rich manganese-based electrolyte's ability to operate for extended periods under high voltage.
[0052] Test 2:
[0053] Figure 2 The charge-discharge curves of the soft-pack battery with graphite and lithium-rich manganese-based cathode matched in Example 1 at 30°C and 4.5V are shown for 1000 cycles at 1C, demonstrating the ability of the intrinsically safe lithium-rich manganese-based high-temperature, high-pressure, high-rate, long-life electrolyte to operate for a long time under high voltage.
[0054] Test 3: Capacity retention rate of pouch battery at 45℃ / 1C / 4.5V / 500 cycles:
[0055] Figure 3 The data from Example 1, which describes a soft-pack battery with a graphite-rich manganese-based cathode matched at 45°C and 4.5V, demonstrates the ability of the intrinsically safe, high-temperature, high-pressure, high-rate, long-life lithium-rich manganese-based electrolyte to operate for extended periods under high temperature and high voltage.
[0056] Test 4: Button cell capacity retention rate at 30℃ / 10C / 4.65V / 750 cycles:
[0057] Figure 4 The data from Example 1, which describes a coin cell with a lithium metal anode and a lithium-rich manganese-based cathode matched at 30°C and 4.65V, demonstrates the ability of the intrinsically safe lithium-rich manganese-based high-temperature, high-pressure, high-rate, and long-life electrolyte to operate for extended periods at high rates.
[0058] Test 5: Button cell capacity retention rate at 30℃ / 1C / 4.8V / 500 cycles:
[0059] Figure 5 The data from Example 1, which describes a coin cell with a lithium metal anode and a lithium-rich manganese-based cathode matched at 30°C and 4.8V, demonstrates the ability of the intrinsically safe lithium-rich manganese-based high-temperature, high-pressure, high-rate, and long-life electrolyte to operate for extended periods under high voltage.
[0060] Test 6: Flammability Test
[0061] The electrolyte of Example 1 was tested for combustion at 30°C. The results showed that it could not burn even after 60 seconds of ignition, proving the non-flammability and safety of the electrolyte.
[0062] Test 7: After the pouch battery is fully charged, a 5mm needle is used for puncture test:
[0063] The soft-pack battery assembled with the electrolyte of Example 1 was charged to 4.5V at 30°C and then subjected to a needle penetration test with a steel needle with a diameter of 5mm. The results showed that the voltage after the needle penetration decreased from the initial 4.311V to 4.007V, and there was no short circuit, proving that the lithium-rich manganese-based battery prepared with this electrolyte met the needle penetration safety test standard.
[0064] Example 2
[0065] Compared to Example 1, the only difference is that the electrolyte composition was changed; the experimental groups were as follows:
[0066] Group A: The carbon ester solvent is DEC, and the weight ratio of DEC, Formula 1, and Formula 2 is 6:2:2. All other operations and parameters are the same as in Example 1.
[0067] Group B: The carbon ester solvent is DMC, and the weight ratio of DMC, Formula 1 and Formula 2 is 6:3:1. All other operations and parameters are the same as in Example 1.
[0068] Group C: The electrolyte contains conductive lithium salt (LiFSI) at a concentration of 1.5 M, and the content of Formula 3 in the composite electrolyte is 1 wt.%; other operations and parameters are the same as in Example 1.
[0069] The results for each group are shown in Table 1:
[0070] Table 1: Test results of Example 1 and Example 2:
[0071] As shown in Table 1, the process described in this invention can produce an intrinsically non-flammable electrolyte, thereby enabling the assembly of a lithium-rich manganese-based battery with intrinsically high safety and excellent high-voltage, high-temperature, and high-rate long-cycle performance.
[0072] Example 3
[0073] Compared to Example 1, the only difference is that the elemental composition and ratio in the lithium-rich manganese-based cathode are changed. The experimental groups are as follows:
[0074] Group A: Lithium-rich manganese-based cathode with Li 1.2 Ni 0.17 Mn 0.50 Co 0.13 O2, other operations and parameters are the same as in Example 1.
[0075] Group B: Lithium-rich manganese-based cathode with Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O2, other operations and parameters are the same as in Example 1.
[0076] Group C: Lithium-rich manganese-based cathode with Li1.17 Ni 0.17 Mn 0.5 Co 0.17 O2, other operations and parameters are the same as in Example 1.
[0077] The results for each group are shown in Table 2:
[0078] Table 2: Test results of Examples 1 and 3:
[0079] As shown in Table 2, the electrolyte described in this invention can be adapted to different lithium-rich manganese-based materials, and can obtain an intrinsically non-flammable electrolyte. This allows for the assembly of lithium-rich manganese-based batteries with intrinsically high safety and excellent high-voltage, high-temperature, and high-rate long-cycle performance.
[0080] Comparative Example 1
[0081] Compared to Example 1, the only difference is that the composition of the electrolyte is changed. The experimental groups are as follows:
[0082] Group A: Replace Equation 1 with the equivalent mass of the comparative Equation A;
[0083] Group B: Replace Equation 1 with Equation B of equal mass;
[0084] Group C: Replace Equation 2 with the equivalent mass of the comparative equation C;
[0085] Group D: Replace Equation 2 with the equivalent mass of the comparative equation D;
[0086] All other operations and parameters are the same as in Example 1, and the results are shown in Table 3:
[0087] Table 3: Test results of each group in the comparative example:
[0088] As can be seen from Example 1 and Comparative Example 1, the combination of the components of Formula 1 and Formula 2 described in this invention can unexpectedly achieve synergy, resulting in an intrinsically non-flammable electrolyte and thereby assembling a lithium-rich manganese-based battery with intrinsically high safety and excellent high-voltage, high-temperature, and high-rate long-cycle performance.
[0089] Comparative Example 2
[0090] Compared to Example 1, the only difference is that the composition of the electrolyte is changed. The experimental groups are as follows:
[0091] Group A: Only the comparative E-type quality replacement formula 3 is used;
[0092] Group B: Only the comparative F-type quality substitution formula 3 is used;
[0093] Group C: Formula 3 is missing from the electrolyte;
[0094] All other operations, parameters, and tests were the same as in Example 1, and the results are shown in Table 4:
[0095] Table 4: Test results of Comparative Example 2:
[0096] As can be seen from Example 1 and Comparative Example 2, Formula 3 of the present invention can unexpectedly achieve synergy with the solvent, which can enhance the compatibility of the electrolyte with lithium-rich manganese-based materials and obtain long-cycle stability under high temperature, high voltage and high rate testing conditions.
[0097] As demonstrated by Examples 1-3 and Comparative Examples 1-2, the present invention employs a combination of Formulas 1-3, achieving synergy. This combination is suitable for the physicochemical characteristics of lithium-rich manganese-based batteries, endows the electrolyte with intrinsic non-flammability, and captures oxygen free radicals generated during cycling at the lithium-rich manganese-based cathode. Lithium-rich manganese-based batteries prepared with this electrolyte meet the nail penetration safety test standards, thus improving the intrinsic safety of the battery. Furthermore, it effectively enhances the high-rate performance of lithium-rich manganese-based batteries, achieving a synergistic improvement in both battery safety and high-rate electrochemical performance.
Claims
1. An electrolyte adapted to lithium-rich manganese-based materials, characterized in that, It is a homogeneous solution containing carbon ester solvents, Formula 1, Formula 2, Formula 3 and conductive lithium salt; Formula 1; Formula 2; Formula 3; In the electrolyte, the mass ratio of carbon ester solvent, Formula 1, and Formula 2 is 6:0.5~3.5:0.5~3.5; the content of Formula 3 is 1~5 wt.%; and the molar concentration of conductive lithium salt is 0.5~5 M.
2. The electrolyte as described in claim 1, characterized in that, Carbon ester solvents include at least one of EMC, DEC, EC, and DMC.
3. The electrolyte as described in claim 1, characterized in that, In the electrolyte, the mass ratio of the carbon ester solvent, Formula 1, and Formula 2 is 6:0.8~1.2:2.8~3.
2.
4. The electrolyte as described in claim 1, characterized in that, The content of Formula 3 in the electrolyte is 2.5~3.5 wt.%.
5. The electrolyte as described in claim 1, characterized in that, The conductive lithium salt includes at least one of LiPF6, LiFSI, and LiTFSI.
6. The electrolyte as described in claim 1, characterized in that, The concentration of the conductive lithium salt is 1~3M.
7. An application of the electrolyte according to any one of claims 1 to 6, characterized in that, It was used as an electrolyte to prepare lithium-rich manganese-based lithium-ion batteries with lithium-rich manganese-based materials as the positive electrode material.
8. A lithium-rich manganese-based lithium-ion battery, wherein the active material in its positive electrode comprises a lithium-rich manganese-based active material, characterized in that, It comprises the electrolyte according to any one of claims 1 to 6.
9. The lithium-rich manganese-based lithium-ion battery as described in claim 8, characterized in that, The chemical formula of the lithium-rich manganese-based active material is Li x Mn y M z O2, wherein M includes Ni and / or Co; 1 <x≤1.5;0.4≤y≤0.8;0<z <0.4。 10. The lithium-rich manganese-based lithium-ion battery according to any one of claims 8 to 9, characterized in that, The active material in the negative electrode of a lithium-rich manganese-based lithium-ion battery is at least one of carbon materials, silicon materials, and silicon-carbon materials. The lithium-rich manganese-based lithium-ion battery is a pouch battery.