Lithium supplement additive, method for producing the same, electrochemical device, and electronic device

Abstract

To provide a lithium supplement additive, its manufacturing method, an electrochemical device, and an electronic device.SOLUTION: A lithium supplement additive includes a component A and a component B. The general chemical formula of the component A is Li6-xM11-yN1yO4-z with 0≤x≤5.95, 0≤y≤1, 0≤z≤2 in the formula, M1 is selected from one or more of Fe, Ni, Co, Cu, Al, Mn, Ti, and Si, and N1 is selected from one or more of Ni, Co, Cu, Al, Mn, Ti, and Si. The general chemical formula of the component B is Li1+(a / (2+a))Mn2a / (2+a)M26 / (2+a)-2O2, 0.2≤a≤1, and at least a part of the component B is located on the surface of the component A. A positive electrode material including the lithium supplement additive of the invention has higher stability and high theoretical capacity, is used for a lithium ion battery, and improves energy density and cycle stability of the battery.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention particularly relates to a lithium replenishing additive, a method for producing the same, an electrochemical device, and an electronic device.

Background Art

[0002] In a lithium-ion battery, the lower initial Coulombic efficiency of the positive electrode and the negative electrode determines the initial efficiency of the entire battery. When the efficiencies of the positive electrode and the negative electrode are equal, the utilization rate of active lithium in the battery is the highest. The initial efficiency of current commercial systems is limited by the low initial efficiency of the negative electrode. Therefore, a large amount of active Li provided by the positive electrode is consumed, and the energy density of the entire battery decreases.

[0003] Some lithium-ion auxiliary materials currently widely studied include Li5FeO4 (LFO), Li2NiO2 (LNO), and Li6CoO4 (LCO). All of these have a very high theoretical capacity and very low reversibility (Coulombic efficiency < 10%), so they are ideal lithium replenishing additives (i.e., positive electrode lithium replenishing additives). However, LFO, LNO, and LCO are unstable in air, easily absorb moisture, generate residual alkali (Li2CO3, LiOH), which not only reduces their electrochemical activity, but also causes gas generation from the battery, battery swelling, and potential safety hazards.

[0004] Based on the above research, in order to improve the energy density and cycle stability of the battery and achieve better stability and high theoretical capacity, it is necessary to provide a lithium replenishing additive that can be used as a positive electrode material.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The technical problem to be solved by the present invention is to overcome the instability of existing lithium auxiliary additives in air, which leads to a decrease in electrochemical activity. When existing lithium auxiliary additives are used in lithium-ion batteries, gas is generated inside the battery, causing potential safety hazards. Accordingly, a lithium replenishing additive, a method for manufacturing the same, a positive electrode sheet, an electrochemical device, and an electronic device are provided. The positive electrode material containing the lithium replenishing additive of the present invention is more stable, has a high theoretical capacity, is used in a lithium-ion battery, and improves the energy density and cycle stability of the battery.

Means for Solving the Problems

[0006] The present invention solves the above technical problems by the following technical solutions.

[0007] In a first aspect, the present invention provides a lithium replenishing additive including component A and component B. The general chemical formula of component A is Li 6-x M 1 1-y N 1 y O 4-z wherein 0 ≦ x ≦ 5.95, 0 ≦ y ≦ 1, 0 ≦ z ≦ 2, and M 1 is selected from one or more of Fe, Ni, Co, Cu, Al, Mn, Ti, and Si, and N 1 is selected from one or more of Fe, Ni, Co, Cu, Al, Mn, Ti, and Si. The general chemical formula of component B is Li 1+(a / (2+a)) Mn 2a / (2+a) M 2 6 / (2+a)-2 O2, 0.2 ≦ a ≦ 1, and M 2 is selected from one or more of Fe, Ni, Co, Cu, Al, Mn, Ti, Si, Mg, Zr, Nb, La, Sr, and W, and at least a part of component B is located on the surface of component A.

[0008] In a second aspect, the present invention also provides a method for manufacturing the lithium replenishing additive, including the step of mixing and sintering precursors of component A and component B to obtain the lithium replenishing additive.

[0009] In a third aspect, the present invention also provides an electrochemical device including a positive electrode sheet containing the lithium replenishing additive, a negative electrode sheet, a separator, and an electrolyte.

[0010] In a fourth aspect, the present invention also provides an electronic device including a positive electrode material containing the lithium replenishing additive or a lithium-ion secondary battery containing the lithium replenishing additive.

[0011] In a fifth aspect, the present invention also provides a positive electrode material containing an active material and a lithium replenishing additive. In the positive electrode material, the mass ratio of the lithium replenishing additive is 0.5% to 31%.

Advantages of the Invention

[0012] The advantageous effects of the present invention are as follows. The positive electrode material containing the lithium replenishing additive of the present invention has higher stability, higher theoretical capacity, is used in a lithium-ion battery, and improves the energy density and cycle stability of the battery.

[0013] Hereinafter, the present invention will be further described by way of examples, but the present invention is not limited to the scope of the examples. For the experimental methods that are not specifically specified in the following examples, conventional methods and conditions or those according to the product manuals are selected.

[0014] In the lithium replenishing additive of the first aspect of the present invention, preferably, M 1 is Fe, Ni, Co, Cu, Al, Mn, Ti, or Si.

[0015] Preferably, N 1 is Fe, Ni, Co, Cu, Al, Mn, Ti, or Si.

[0016] Preferably, M 2 is Fe, Ni, Co, Cu, Al, Mn, Ti, Si, Mg, Zr, Nb, La, Sr, or W.

[0017] Preferably, the range of the value of x is 0 ≤ x ≤ 5, for example, 0.4, 0.5, 0.8, 1, 2 or 4.

[0018] Preferably, the range of the value of y is 0 ≤ y ≤ 0.9, for example, 0.2, 0.5, 0.6 or 0.8.

[0019] Preferably, the range of the value of z is 0 ≤ z ≤ 2, for example, 0.4, 0.5, 0.8, 1 or 1.5.

[0020] Preferably, the range of the value of a is 0.22 ≤ a ≤ 1, for example, 0.3, 0.5, 0.7 or 0.8.

[0021] Preferably, at least a part of component B is coated on the surface of component A. Preferably, the mass ratio of component A to the total mass of "component A and component B" is 89% - 99.1%, for example, 90%, 92%, 95%, 96%, 97%, 98% or 99%.

[0022] Preferably, the lithium - supplement additive has a core - shell structure. The average particle size of the core of the core - shell structure may be 0.5 μm - 15 μm. The average thickness of the shell of the core - shell structure may be 20 nm - 200 nm.

[0023] In some preferred embodiments of the present invention, the chemical formula of the lithium - supplement additive is ALi 5+e Fe 1-e Co e O4 / (1 - A)Li 1.33 Mn 0.67 O2 or ALi2Ni 1-f Cu f O2 / (1 - A)Li 1.33 Mn 0.67 O2, where 0.8 ≤ A < 1; 0 ≤ e ≤ 1; 0 ≤ f ≤ 1.

[0024] A is Li 5+e Fe 1-e Co e O4 / Li 1.33 Mn0.67 Li in O2 5+e Fe 1-e Co e The mass ratio of O4, or Li2Ni 1-f Cu f O2 / Li 1.33 Mn 0.67 Li2Ni in O2 1-f Cu f Indicates the mass ratio of O2.

[0025] In some preferred embodiments of the present invention, the range of the value of A is preferably 0.89 ≦ A ≦ 0.991, for example, 0.9, 0.96, 0.97, 0.98 or 0.99.

[0026] In some preferred embodiments of the present invention, the range of the value of e is 0.2 ≦ e ≦ 1, for example, 0.5 or 0.4.

[0027] In some preferred embodiments of the present invention, the range of the value of f is 0.5 ≦ f ≦ 1, for example, 0.8.

[0028] In some preferred embodiments of the present invention, the general chemical formula of component A is Li 6-x M 1 1-y N 1 y O 4-z where 0 ≦ x ≦ 5.95, 0 ≦ y ≦ 1, 0 ≦ z ≦ 2, and M 1 is Fe, Ni, Co, Cu, Al, Mn, Ti, or Si, and N 1 is Fe, Ni, Co, Cu, Al, Mn, Ti, or Si. The general chemical formula of component B is Li 1+(a / (2+a)) Mn 2a / (2+a) M 2 6 / (2+a)-2 O2, 0.2 ≦ a ≦ 1, and M 2 is Fe, Ni, Co, Cu, Al, Mn, Ti, Si, Mg, Zr, Nb, La, Sr, or W. At least a part of component B is coated on the surface of component A.

[0029] In some preferred embodiments of the present invention, the chemical formula of component A is Li2NiO2, Li2Ni 0.5 Cu 0.5 O2, Li2Ni 0.8 Cu 0.2 O2, Li2Ni 0.4 Cu 0.6 O2, Li2Cu2O2, Li5FeO4, Li 5.5 Fe 0.5 Co 0.5 O4, Li 5.2 Fe 0.8 Co 0.2 O4, Li 5.6 Fe 0.4 Co 0.6 O4 or Li6CoO4, and the chemical formula of component B is Li 1.33 Mn 0.67 O2, Li 1.26 Mn 0.63 Ni 0.11 O2, Li 1.2 Mn 0.6 Ni 0.2 O2 or Li 1.1 Mn 0.75 Ni 0.25 O2.

[0030] In some preferred embodiments of the present invention, the chemical formula of component A is Li2NiO2, Li2Ni 0.5 Cu 0.5 O2, Li2Ni 0.8 Cu 0.2 O2, Li2Ni 0.4 Cu 0.6 O2, Li2Cu2O2, Li5FeO4, Li 5.5 Fe 0.5 Co 0.5 O4, Li 5.2 Fe 0.8 Co 0.2 O4, Li 5.6 Fe 0.4 Co 0.6 O4 or Li6CoO4, and the chemical formula of component B is Li 1.33 Mn 0.67 O2.

[0031] In some preferred embodiments of the present invention, the chemical formula of component A is Li2NiO2, and the chemical formula of component B is Li 1.26 Mn 0.63 Ni 0.11 O2, Li 1.2 Mn 0.6 Ni 0.2 O2 or Li 1.1 Mn 0.75 Ni 0.25 O2.

[0032] In the method for producing the lithium replenishment additive according to the second aspect of the present invention, preferably, the precursor of component A is first sintered to obtain component A, and then mixed with the precursor of component B.

[0033] The precursor of component A may be a conventional precursor in the art that can be produced to satisfy the general chemical formula of component A, such as Li2O and NiO or Fe2O3 and LiOH. Generally, the amount of each component of component A may be selected according to the corresponding stoichiometric amount according to the chemical formula of the obtained component A.

[0034] The temperature and time of the first sintering may be conventional temperatures and times in the art. Generally, the desirable first sintering temperature and time also vary depending on the type of the precursor of component A selected. For example, when the precursor of component A is Li2O and NiO, the temperature of the first sintering is 600 °C, and the time of the first sintering is 12 hours. When the precursor of component A is Fe2O3 and LiOH, the first sintering is carried out in two steps. The temperature of the first step is 450 °C, the time of the first step is 12 hours, the temperature of the second step is 600 °C, and the time of the second step is 24 hours.

[0035] Preferably, the precursor of component B may be a conventional precursor in the art that can be produced to satisfy the general chemical formula of component B, such as MnCO3 and Li2CO3. Generally, the amount of each component of component B may be selected according to the corresponding stoichiometric amount according to the chemical formula of the obtained component B.

[0036] Preferably, the sintering temperature and time may be the conventional temperature and time in the relevant technical field. Generally, the desirable sintering temperature and time also vary depending on the type of precursor of component B to be selected. For example, when the precursors of component B are MnCO3 and Li2CO3, the sintering temperature of the sintering component is 500 °C and the sintering time is 72 hours.

[0037] In the third form of the positive electrode sheet, preferably, the mass ratio of the lithium replenishing additive to the total mass of the positive electrode sheet is 0.5% to 31%, for example, 0.9%, 1%, 2%, 5%, 10%, 15%, 18%, 20%, 25%, 28% or 30%.

[0038] Preferably, lithium iron phosphate is LiFePO4.

[0039] Preferably, lithium manganese iron phosphate is LiMn 0.6 Fe 0.4 PO4.

[0040] Preferably, the ternary material of nickel, cobalt and manganese is LiNi 0.9 Co 0.06 Mn 0.04 O2.

[0041] Preferably, lithium cobalt oxide is LiCoO2.

[0042] Preferably, the lithium-rich manganese-based oxide is Li 1.1 Ni 0.4 Mn 0.6 O2.

[0043] Preferably, lithium nickel manganese oxide is LiNi 1.5 Mn 0.5 O4.

[0044] In some preferred embodiments of the present invention, the active material is lithium iron phosphate, lithium manganese iron phosphate, ternary material of nickel, cobalt and manganese, lithium cobalt oxide, lithium-rich manganese-based oxide or Lithium nickel manganese oxideIt is. The chemical formula of the lithium supplement additive is ALi 5+e Fe 1-e Co e O4 / (1 - A)Li 1.33 Mn 0.67 O2 or ALi2Ni 1-f Cu f O2 / (1 - A)Li 1.33 Mn 0.67 O2. Specifically, 0.8 ≤ A < 1, 0 ≤ e ≤ 1, 0 ≤ f ≤ 1, and A represents the mass ratio of Li 5+e Fe 1-e Co e O4 / Li 1.33 Mn 0.67 O2 in Li 5+e Fe 1-e Co e O4, or the mass ratio of Li2Ni 1-f Cu f O2 / Li 1.33 Mn 0.67 O2 in Li2Ni 1-f Cu f O2.

[0045] In some preferred embodiments of the present invention, the active material is LiMn 0.6 Fe 0.4 PO4, and the lithium supplement additive is Li2NiO2 / Li 1.33 Mn 0.67 O2, Li2Ni 0.5 Cu 0.5 O2 / Li 1.33 Mn 0.67 O2, Li2Ni 0.8 Cu 0.2 O2 / Li 1.33 Mn 0.67 O2, Li2Ni 0.4 Cu 0.6 O2 / Li 1.33 Mn 0.67 O2, Li2Cu2O2 / Li 1.33 Mn 0.67 O2, Li5FeO4 / Li 1.33 Mn 0.67 O2, Li 5.5 Fe 0.5 Co 0.5 O4 / Li 1.33 Mn 0.67O2, Li 5.2 Fe 0.8 Co 0.2 O4 / Li 1.33 Mn 0.67 O2, Li 5.6 Fe 0.4 Co 0.6 O4 / Li 1.33 Mn 0.67 O2, Li6CoO4 / Li 1.33 Mn 0.67 O2, Li2NiO2 / Li 1.26 Mn 0.63 Ni 0.11 O2, Li2NiO2 / Li 1.2 Mn 0.6 Ni 0.2 O2 or Li2NiO2 / Li 1.1 Mn 0.75 Ni 0.25 is O2.

[0046] In some preferred embodiments of the present invention, the active material is LiMn 0.6 Fe 0.4 PO4, LiFePO4, LiNi 0.9 Co 0.06 Mn 0.04 O2, Li 1.1 Ni 0.4 Mn 0.6 O2, LiCoO2 or LiNi 1.5 Mn 0.5 O4, and the lithium replenishing additive is Li2NiO2 / Li 1.33 Mn 0.67 is O2.

[0047] In the method for manufacturing the positive electrode sheet of the fourth aspect, preferably, the positive electrode current collector may be a conventional positive electrode current collector in the art, generally an aluminum foil.

[0048] Preferably, the drying method may be a conventional method in the art.

[0049] Preferably, the drying temperature may be a conventional temperature in the art, for example, 120 °C.

[0050] Preferably, the drying time may be a normal time in the relevant technical field, for example, 10 minutes.

[0051] Preferably, the slurry usually also contains a conductive agent, a solvent, and an adhesive.

[0052] Specifically, the conductive agent may be a conventional conductive agent in the relevant technical field, for example, conductive carbon black (Super P).

[0053] Specifically, the solvent may be a conventional solvent in the relevant technical field, preferably N-methylpyrrolidone (NMP).

[0054] Specifically, the adhesive may be a conventional adhesive in the relevant technical field, for example, polyvinylidene fluoride (PVDF).

[0055] Preferably, when the slurry contains an active material, a lithium replenishing additive, a conductive agent, and a binder, the mass ratio of "the positive electrode active material and the lithium replenishing additive", the conductive agent, and the binder is (93-98):(1-4):(1-4), for example, 97:1.5:1.5.

[0056] In some preferred embodiments of the present invention, the method for manufacturing a positive electrode sheet includes a step of coating a slurry containing an active material and a lithium replenishing additive on at least one side of an aluminum foil and drying it at 120°C for 10 minutes.

[0057] In the positive electrode material of the seventh aspect, preferably, the range of the value of A is 0.89 ≦ A ≦ 0.991, for example, 0.9, 0.96, 0.97, 0.98, or 0.99.

[0058] Preferably, the range of the value of e is 0.2 ≦ e ≦ 1, for example, 0.5 or 0.4.

[0059] Preferably, the range of the value of f is 0.5 ≦ f ≦ 1, for example, 0.8.

[0060] Preferably, the mass ratio of the lithium replenishing additive in the positive electrode material is 0.9% to 31%, for example, 1%, 2%, 5%, 10%, 15%, 18%, 20%, 25%, 28% or 30%.

[0061] Preferably, lithium iron phosphate is LiFePO4.

[0062] Preferably, lithium manganese iron phosphate is LiMn 0.6 Fe 0.4 PO4.

[0063] Preferably, the ternary system material of nickel, cobalt and manganese is LiNi 0.9 Co 0.06 Mn 0.04 O2.

[0064] Preferably, lithium cobalt oxide is LiCoO2.

[0065] Preferably, the lithium-rich manganese-based oxide is Li 1.1 Ni 0.4 Mn 0.6 O2.

[0066] Preferably, l lithium nickel manganese oxide is LiNi 1.5 Mn 0.5 O4.

[0067] In some preferred embodiments of the present invention, the active material is LiMn 0.6 Fe 0.4 PO4, and the lithium replenishing additive is Li2NiO2 / Li 1.33 Mn 0.67 O2, Li2Ni 0.5 Cu 0.5 O2 / Li 1.33 Mn 0.67 O2, Li2Ni 0.8 Cu 0.2 O2 / Li 1.33 Mn 0.67 O2, Li2Ni 0.4 Cu 0.6 O2 / Li1.33 Mn 0.67 O2, Li2Cu2O2 / Li 1.33 Mn 0.67 O2, Li5FeO4 / Li 1.33 Mn 0.67 O2, Li 5.5 Fe 0.5 Co 0.5 O4 / Li 1.33 Mn 0.67 O2, Li 5.2 Fe 0.8 Co 0.2 O4 / Li 1.33 Mn 0.67 O2, Li 5.6 Fe 0.4 Co 0.6 O4 / Li 1.33 Mn 0.67 O2, Li6CoO4 / Li 1.33 Mn 0.67 O2, Li2NiO2 / Li 1.26 Mn 0.63 Ni 0.11 O2, Li2NiO2 / Li 1.2 Mn 0.6 Ni 0.2 O2 or Li2NiO2 / Li 1.1 Mn 0.75 Ni 0.25 is O2.

[0068] In some preferred embodiments of the present invention, the active material is LiMn 0.6 Fe 0.4 PO4, LiFePO4, LiNi 0.9 Co 0.06 Mn 0.04 O2, Li 1.1 Ni 0.4 Mn 0.6 O2, LiCoO2 or LiNi 1.5 Mn 0.5 O4, and the lithium replenishing additive is Li2NiO2 / Li 1.33 Mn 0.67 is O2.

[0069] Based on the common general knowledge in the technical field, preferred examples of the present invention can be obtained by arbitrarily combining the above preferred conditions.

[0070] Example 1

[0071] The manufacturing process of the lithium replenishment additive in Example 1 was as follows. First, Component A was prepared. Next, the precursor of Component B was mixed with Component A to form Component B on the surface of Component A. Specifically, stoichiometric ratios of Li2O and NiO were taken out, pulverized, and mixed, and then sintered at 600 °C for 12 hours under N2 to obtain Component A (Li2NiO2). Next, 0.9 M of Li2NiO2 was taken out, uniformly mixed with the precursor of Component B (0.02 M of MnCO3, 0.02 M of Li2CO3), and sintered at 500 °C for 72 hours to produce the lithium replenishment additive (here, Component B was partially coated on the surface of Component A, and the chemical formula of Component B was Li2NiO2 / Li 1.33 Mn 0.67 O2).

[0072] The cathode material in the cathode sheet of Example 1 was LiMn 0.6 Fe 0.4 PO4 (Component C, i.e., the active material) and Li2NiO2 / Li 1.33 Mn 0.67 O2 (Component A + Component B, i.e., the lithium replenishment additive). Here, the proportion of Component C in the total mass of "Component A + Component B + Component C + Super P + PVDF" was 92.15%, and the mass ratio of "Component A + Component B" to the total mass of "Component A + Component B + Component C" was 5%. The cathode material of the cathode sheet further included conductive carbon black (Super P) and polyvinylidene fluoride (PVDF). LiMn 0.6 Fe 0.4 PO4 did not react with Li2NiO2 / Li 1.33 Mn 0.67 O2 and was only physically mixed. The mass ratio of "Component A + Component B + Component C", Super P, and PVDF was 97:1.5:1.5.

[0073] The method for fabricating the positive electrode sheet of Example 1 includes the following steps. First, the active material, Super P, and PVDF were mixed at the above ratios, and then N-methylpyrrolidone (NMP) was gradually added while stirring at high speed to prepare a positive electrode slurry having a certain viscosity. Next, the prepared slurry was uniformly coated on an aluminum foil and dried in a blowing drying oven at 120°C for 10 minutes. Finally, the dried electrode sheet was rolled and cut to fabricate the positive electrode sheet.

[0074] In Example 24, the specific manufacturing process of the lithium replenishing additive was formed by mixing Fe2O3 and LiOH at a ratio of 1:10, then sintering at 450°C for 12 hours under N2 and cooling. After pulverization, the mixture was sintered at 600°C for 24 hours under N2 to obtain LFO, that is, Component A (Li5FeO4). Then, 0.9 M of Li5FeO4 was taken out and uniformly mixed with the precursor of Component B (0.02 M of MnCO3, 0.02 M of Li2CO3), and sintered at 500°C for 72 hours.

[0075] In Examples 2 to 6, except that the type of Component C in the positive electrode material was changed (shown in Table 2), all other experimental conditions were the same as those in Example 1. Component C may be a conventional commercially available product.

[0076] In Examples 7 to 13, except that the mass ratio of “Component A + Component B” in the positive electrode material was changed (shown in Table 2), all other experimental conditions were the same as those in Example 1.

[0077] In Examples 14 to 19, except that the mass ratio of Component A to the total mass of “Component A + Component B” was changed (shown in Table 2), all other experimental conditions were the same as those in Example 1.

[0078] In Examples 20 to 28, except for changing the type of Component A (shown in Table 1), all other experimental conditions were the same as those in Example 1. When Component A is LixFeOy, the precursors of Component A are Fe2O3 and LiOH, and the relative mass ratio of each precursor can be adjusted according to the final chemical formula of the designed Component A. When Component A is LixNiCuO, the precursors of Component A are NiO, CuO, and Li2O, and the relative mass ratio of each precursor can be adjusted according to the final chemical formula of the designed Component A.

[0079] In Examples 29 to 31, except for changing the type of Component B (shown in Table 1), all other experimental conditions were the same as those in Example 1. The precursors of Component B are Li2CO3, MnCO3, NiCO3, and CoCO3, and the relative mass ratio of each precursor can be adjusted according to the final chemical formula of the designed Component B.

[0080] The lithium-supplemented additive (Component A + Component B) produced in Examples 1 to 31 had a core-shell structure. Specifically, the average particle size of the core was 0.5 μm to 15 μm, and the average thickness of the shell was 20 nm to 200 nm.

[0081] Example 2

[0082] LiFePO4 (Component C)

[0083] Li2NiO2 / Li 1.33 Mn 0.67 O2 (Component A + Component B)

[0084] Specifically, the proportion of Component C in the total mass of "Component A + Component B + Component C + Super P + PVDF" was 92.15%. The mass ratio of "Component A + Component B" to the total mass of "Component A + Component B + Component C" was 5%.

[0085] Cycle test voltage range: 2.5V to 3.65V

[0086] Example 3

[0087] LiNi 0.9 Co 0.06 Mn 0.04 O2 (Component C)

[0088] Li2NiO2 / Li 1.33 Mn 0.67 O2 (Component A + Component B)

[0089] Specifically, the proportion of Component C in the total mass of "Component A + Component B + Component C + Super P + PVDF" was 92.15%. The mass ratio of "Component A + Component B" to the total mass of "Component A + Component B + Component C" was 5%.

[0090] Cycle test voltage range: 2.8V to 4.2V

[0091] Example 4

[0092] LiNi 1.5 Mn 0.5 O4 (Component C)

[0093] Li2NiO2 / Li 1.33 Mn 0.67 O2 (Component A + Component B)

[0094] Specifically, the proportion of Component C in the total mass of "Component A + Component B + Component C + Super P + PVDF" was 92.15%. The mass ratio of "Component A + Component B" to the total mass of "Component A + Component B + Component C" was 5%.

[0095] Cycle test voltage range: 2.8V to 4.45V

[0096] Example 5

[0097] LiCoO2 (Component C)

[0098] Li2NiO2 / Li 1.33 Mn 0.67 O2 (Component A + Component B)

[0099] Specifically, the proportion of Component C in the total mass of "Component A + Component B + Component C + Super P + PVDF" was 92.15%. The mass ratio of "Component A + Component B" to the total mass of "Component A + Component B + Component C" was 5%.

[0100] Cyclic test voltage range: 2.8V to 4.7V

[0101] The main conditional parameters included in the examples are as shown in Table 1 below.

Table 1

[0102] The main conditional parameters included in the examples are as shown in Table 1 below.

Table 1

[0103] (1) Rebound test of solid content and viscosity

[0104] Test objects: Cathode sheets manufactured in Examples 1 to 31 and Comparative Examples 1 to 8.

[0105] Test method: The viscosity of the cathode slurry was adjusted to 5000 ± 500 mPa·s, the actual solid content was tested, the cathode slurry was placed in a 500 mL beaker for 12 hours, and the viscosity was tested again.

[0106] Test results: As shown in Table 2 below.

[0107] The manufacturing methods of the test target batteries in Examples (2) to (4) regarding the following effects are as follows. The prepared positive electrode sheet and the graphite negative electrode sheet were mounted to fabricate a 1 Ah soft pack battery. After liquid injection, a forming process at 4.5 V was performed (i.e., the first charging process of the battery after liquid injection, by which the active materials in the battery are activated and the lithium battery is activated). Then, after the aging process, a new battery was obtained.

[0108] (2) Capacity Test

[0109] Test method: For the battery cell with the positive electrode fabricated in the example, constant current constant voltage charging (termination current 0.05C) was performed at 25°C, 2.0 V to 4.2 V, and 0.33°C, and constant current discharging was performed at 0.33C. The discharge capacity is that value.

[0110] Test results: As shown in Table 2 below.

[0111] (3) Cycle Test

[0112] Test method: The battery cell with the positive electrode fabricated in the example was charged and discharged 500 cycles at 45°C and 1C in the range of 2.5 V to 4.2 V, and the capacity ratio of the 500th cycle to the first cycle was recorded as the capacity retention rate.

[0113] Test results: As shown in Table 2 below.

[0114] (4) Storage Gas Production Test

[0115] Test method: The battery cell with the positive electrode fabricated in the example was fully charged and stored at 60°C and 4.2 V, the capacity difference between the 30th day and the first day was recorded, and this value was divided by the capacity on the first day to calculate the storage capacity increase rate.

[0116] Test results: As shown in Table 2 below.

Table 2

[0117] Analyzing the data in Tables 1 to 2 reveals the following. Compared with Example 1, Examples 7 to 13 only change the mass ratio of "Component A + Component B" in the "total mass of Component A + Component B + Component C", and other conditions are the same. Therefore, it has various degrees of influence on the gram capacity, the cycle capacity retention rate at 45°C, and the storage capacity increase rate at 60°C. Specifically, when the mass ratio of "Component A + Component B" in the "total mass of Component A + Component B + Component C" is 5% or less, for example, when it is 1% to 5%, as the mass ratio increases, the gram capacity and the cycle capacity retention rate at 45°C also increase, while the storage capacity increase rate at 60°C decreases. When the mass ratio of "Component A + Component B" in the "total mass of Component A + Component B + Component C" exceeds 5% and is 35% or less, for example, when it is 5% to 31%, as the mass ratio increases, the gram capacity and the cycle capacity retention rate at 45°C decrease, while the storage capacity increase rate at 60°C increases.

[0118] Compared with Example 1, Examples 14 to 19 only change the mass ratio of Component A in the "total mass of Component A + Component B", and other conditions are the same. Therefore, it has various degrees of influence on the gram capacity, the cycle capacity retention rate at 45°C, and the storage capacity increase rate at 60°C. Specifically, when the mass ratio of Component A to the "total mass of Component A + Component B" exceeds 89%, for example, when it is 98% to 99.1%, as the mass ratio increases, the gram capacity and the cycle capacity retention rate at 45°C basically do not change, while the storage capacity increase rate at 60°C increases. When the mass ratio of Component A to the "total mass of Component A + Component B" is less than 98%, such as 89% to 97%, as the mass ratio decreases, the gram capacity and the cycle capacity retention rate at 45°C slightly decrease, while the storage capacity increase rate at 60°C decreases.

[0119] Compared with Example 1, Examples 20 to 28 only changed the type of Component A, and other conditions were the same. They had various degrees of influence on the gram capacity, the cycle capacity retention rate at 45 °C, and the storage capacity increase rate at 60 °C. For example, in Example 23, when Component A was Li2Cu2O2, the gram capacity was 134.8 mAh / g, the cycle capacity retention rate at 45 °C was 92.4%, and the storage capacity increase rate at 60 °C was 4.6%. Compared with Examples 1, 20 to 22, 24 to 28, Example 23 had the smallest storage capacity increase rate at 60 °C.

[0120] Compared with Example 1, Examples 29 to 31 only changed the type of Component B, and other conditions were the same. They had various degrees of influence on the gram capacity, the cycle capacity retention rate at 45 °C, and the storage capacity increase rate at 60 °C. For example, in Example 1, when Component B was Li 1.33 Mn 0.67 O2, the gram capacity was (137.6 mAh / g), the cycle capacity retention rate at 45 °C was (92.8%), and the storage capacity increase rate at 60 °C was (5.3%), all of which were better than those in Examples 29 to 31.

[0121] Compared with Example 1, Li2NiO2 / Li 1.33 Mn 0.67 O2 is not included in Comparative Example 1, but both the gram capacity and the cycle capacity retention rate at 45 °C in Comparative Example 1 decreased, and the storage capacity increase rate at 60 °C increased.

[0122] Compared with Example 2, Li2NiO2 / Li 1.33 Mn 0.67 O2 is not included in Comparative Example 2, but both the gram capacity and the cycle capacity retention rate at 45 °C in Comparative Example 2 decreased, and the storage capacity increase rate at 60 °C increased.

[0123] Compared with Example 3, Li2NiO2 / Li 1.33 Mn 0.67 O2 is not included in Comparative Example 3, but both the gram capacity and the cycle capacity retention rate at 45 °C in Comparative Example 3 decreased, and the storage capacity increase rate at 60 °C increased.

[0124] Compared with Example 4, Li2NiO2 / Li 1.33 Mn 0.67 O2 is not included in Comparative Example 4, but both the gram capacity and the cycle capacity retention rate at 45 °C of Comparative Example 4 decreased, and the storage capacity increase rate at 60 °C increased.

[0125] Compared with Example 5, Li2NiO2 / Li 1.33 Mn 0.67 O2 is not included in Comparative Example 5, but both the gram capacity and the cycle capacity retention rate at 45 °C of Comparative Example 5 decreased, and the storage capacity increase rate at 60 °C increased.

[0126] Compared with Example 6, Li2NiO2 / Li 1.33 Mn 0.67 O2 is not included in Comparative Example 6, but both the gram capacity and the cycle capacity retention rate at 45 °C of Comparative Example 6 decreased, and the storage capacity increase rate at 60 °C increased.

[0127] Compared with Examples 1 to 19, Comparative Example 7 does not contain "Component A + Component B", but both the gram capacity and the cycle capacity retention rate at 45 °C of Comparative Example 7 decreased, and the storage capacity increase rate at 60 °C increased.

[0128] Compared with Example 24, Comparative Example 8 does not contain "Component A + Component B", but both the gram capacity and the cycle capacity retention rate at 45 °C of Comparative Example 8 decreased significantly, and the storage capacity increase rate at 60 °C increased significantly.

[0129] By analyzing the above data, the inventors concluded that the reasons for the above experimental phenomena are as follows. 1. The increase in the amount of the lithium replenishment additive "Component A + Component B" for the active material component C improves the circulation and storage. However, the lithium replenishment additive "Component A + Component B" has poor conductivity, and if it is too much, it will have an adverse effect on the electrical properties of the positive electrode material and cause deterioration of the positive electrode material.

[0130] 2. The main function of Component B is to stabilize Component A, and its secondary function is to supply lithium. The main function of Component A is to supply lithium. With the increase of Component B, the stability of the lithium supplement additive "Component A + Component B" is improved. However, if there is too much Component B, the lithium supply effect of the lithium supplement additive "Component A + Component B" will decrease.

[0131] 3. When the types of Component A are different, the electrochemical properties are also different.

[0132] Furthermore, the inventors have experimentally found that by adjusting the firing temperature, Component B in the lithium supplement additive can be more uniformly coated on the surface of Component A. Specifically, the Mn source in the precursor of Component B is first fired at a low temperature (for example, 300°C to 500°C), coated on the surface of Component A, and then fired at a high temperature (for example, 600°C to 900°C) to react with the Li source in the precursor of Component B, so as to better form a lithium supplement additive in which Component B is more uniformly coated on the surface of Component A.

Industrial Applicability

[0133] The cathode material containing the lithium supplement additive of the present invention has higher stability, higher theoretical capacity, is used in lithium-ion batteries, and improves the energy density and cycle stability of the batteries.

[0134] As described above, the object, technical solution, and advantageous effects of the present invention have been further described in detail by specific embodiments. It should be understood that the above description is only a specific embodiment of the present invention and does not limit the present invention. All modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of the present invention.

Claims

1. comprising component A and component B, The general chemical formula of the component A is Li ６－ｘ M １ １－ｙ N １ ｙ O ４－ｚ wherein 0 ≤ x ≤ 5.95, 0 ≤ y ≤ 1, 0 ≤ z ≤ 2, and M １ is selected from one or more of Fe, Ni, Co, and Cu, and N １ is selected from one or more of Fe, Ni, Co, and Cu. The general chemical formula of the component B is Li １＋（ａ／（２＋ａ）） Mn ２ａ／（２＋ａ） M ２ ６／（２＋ａ）－２ O ２ , where 0.2 ≤ a ≤ 1, and M ２ is Ni, wherein at least a part of the component B is a lithium replenishing additive located on the surface of the component A.

2. The lithium replenishing additive according to claim 1, satisfying one or more of the following conditions a to b. a. said M １ is Fe, Ni, Co, or Cu. b. The N １ is Fe, Ni, Co, or Cu.

3. The lithium replenishing additive according to claim 1, satisfying one or more of the following conditions d to j. d. The value range of x is 0 ≤ x ≤ 5. e. The value range of y is 0 ≤ y ≤ 0.

9. f. The value range of z is 0 ≤ z ≤ 2. g. The value range of a is 0.22 ≤ a ≤ 1. h. At least a part of the component B is coated on the surface of the component A. i. The mass ratio of component A in the total mass of "the component A and the component B" is 89% to 99.1%. j. The lithium replenishing additive has a core-shell structure.

4. The chemical formula of the lithium supplement additive is ALi ５＋ｅ Fe １－ｅ Co ｅ O ４ / (1 - A)Li １．３３ Mn0.67O ２ or ALi ２ Ni １－ｆ Cu ｆ O ２ / (1 - A)Li １．３３ Mn0.67O ２ where wherein 0.8 ≤ A < 1; 0 ≤ e ≤ 1; 0 ≤ f ≤ 1, A is Li ５＋ｅ Fe １－ｅ Co ｅ O ４ / Li １．３３ Mn0.67O ２ The mass ratio of Li ５＋ｅ Fe １－ｅ Co ｅ O ４ or the mass ratio of Li ２ Ni １－ｆ Cu ｆ O ２ / Li １．３３ Mn0.67O ２ in Li ２ Ni １－ｆ Cu ｆ O ２ The lithium replenishing additive according to claim 1, which indicates the mass ratio of

5. The general chemical formula of the component A is Li ６－ｘ M １ １－ｙ N １ ｙ O ４－ｚ wherein 0 ≤ x ≤ 5.95, 0 ≤ y ≤ 1, 0 ≤ z ≤ 2, and M １ is Fe, Ni, Co, or Cu, N １ is Fe, Ni, Co, or Cu, the general chemical formula of the component B is Li １＋（ａ／（２＋ａ）） Mn ２ａ／（２＋ａ） M ２ ６／（２＋ａ）－２ O ２ where 0.2 ≤ a ≤ 1, and M ２ is Ni, and at least a part of the component B is coated on the surface of the component A. The lithium replenishing additive according to claim 1.

6. A method for manufacturing the lithium replenishing additive according to claim 1, comprising the step of mixing and sintering precursors of the component A and the component B to obtain the lithium replenishing additive.

7. An electrochemical device comprising a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte, wherein the positive electrode sheet comprises a positive electrode current collector, a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, and a lithium replenishing additive, the positive electrode active material layer contains an active material, and the active material contains one or more of lithium iron phosphate, lithium manganese iron phosphate, nickel-cobalt-manganese ternary system material, lithium cobaltate, lithium-rich manganese-based oxide, and lithium nickel manganese oxide, The lithium iron phosphate and lithium manganese iron phosphate each independently have a structural formula: Li ａ Mn ｍ Fe １－ｍ－ｎ M ３ ｎ PO ４ which satisfies the following conditions: 0.9 ≤ a ≤ 1.10, 0 ≤ m ≤ 1.0, 0 ≤ n ≤ 0.02, 0.5 ≤ m / (1 - m - n) ≤ 0.9, and the element M ３ contains one or more of Ti, Mg, Ni, Co, Al, V, Cr, Zr, and Nb. The nickel-cobalt-manganese ternary material has the structural formula: Li １＋ａ [Ni ｘ Co ｙ Mn ｚ N ２ １－ｘ－ｙ－ｚ O ２－ｂ A ｂ , satisfying 0.7 ≤ x < 1, 0 ≤ y < 0.3, 0 ≤ z < 0.3, -0.2 < a < 0.2, 0 ≤ b < 0.

1. In the formula, the N ２ element contains one or more of Sr, Y, Al, Ti, Mg, W, Mo, B, V, Se, Nb, Ru, Rh, Pd, Sb, Te, Ce, Ca, Zn, Ni, Co, Mn, Zr, and the A element contains one or more of F, N, Cl, S, P. The lithium cobaltate has a structural formula: Li ａ Co １－ｂ M ４ ｂ O ２－ｂ and satisfies the formula, where M ４ element is selected from one or more of Na, Mg, Al, Ti, Zr, Y, Ha, Ni, Mn, V, Cr, La, Ce, 0.99 ≦ a ≦ 1.01, 0 < b ≦ 0.05, The lithium-rich manganese-based oxide has a structural formula: zLi ２ MnO ３ ·(1 - z)LiM ５ O ２ , satisfying 0 ≤ z ≤ 1, and M ５ is selected from one or more of Ni, Co, and Mn, The lithium nickel manganese oxide has a structural formula: LiM ６ ｘ＋ｙ Ni ０．５－ｘ Mn １．５－ｙ O ４ and satisfies the formula, where M ６ The element is selected from one or more of Co, Al, Cr, Fe, Mg, Zr, and Ti, 0 ≦ x < 0.2, 0 ≦ y < 0.2, and the lithium replenishing additive contains component A and component B, The general chemical formula of Component A is Li ６－ｘ M １ １－ｙ N １ ｙ O ４－ｚ where 0 ≤ x ≤ 5.95, 0 ≤ y ≤ 1, 0 ≤ z ≤ 2, and M １ is selected from one or more of Fe, Ni, Co, and Cu, and N １ is selected from one or more of Fe, Ni, Co, and Cu. The general chemical formula of Component B is Li １＋（ａ／（２＋ａ）） Mn ２ａ／（２＋ａ） M ２ ６／（２＋ａ）－２ O ２ , where 0.2 ≤ a ≤ 1, and M ２ is Ni, and at least a part of the component B is located on the surface of the component A.

8. The active material is lithium iron phosphate, lithium manganese iron phosphate, nickel-cobalt-manganese ternary system material, lithium cobalt oxide, lithium-rich manganese-based oxide or lithium nickel manganese oxide, and the chemical formula of the lithium supplement additive is ALi ５＋ｅ Fe １－ｅ Co ｅ O ４ / (1 - A)Li １．３３ Mn0.67O ２ or ALi ２ Ni １－ｆ Cu ｆ O ２ / (1 - A)Li １．３３ Mn0.67O ２ where where 0.8 ≤ A < 1; 0 ≤ e ≤ 1; 0 ≤ f ≤ 1, and A is the mass ratio of Li ５＋ｅ Fe １－ｅ Co ｅ O ４ / Li １．３３ in Li ５＋ｅ Fe １－ｅ Co ｅ O ４ or the mass ratio of Li ２ Ni １－ｆ Cu ｆ O ２ / Li １．３３ in Li ２ Ni ２ Cu １－ｆ O ｆ O ２ in the electrochemical device according to claim 7.

9. An electronic device comprising the electrochemical device according to claim 7.

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