A negative electrode active material and its preparation, negative electrode sheet and lithium ion battery

Abstract

The present invention relates to the technical field of battery materials, and in particular to a negative electrode active material and its preparation, a negative electrode sheet and a lithium ion battery. The chemical composition of a negative electrode active material of the present invention is Pb w Sn x M y O z ; wherein M is one or two of vanadium, chromium, carbon, manganese, sulfur, iron, phosphorus, niobium, antimony, and cobalt; the molar number of w is 1-3; the molar number of x is 0 or 1; the molar number of y is 1-5; the molar number of z is 1-8; Pb or Sn exists in the form of ions in Pb w Sn x M y O z The negative electrode active material of the present invention performs a lithium storage reaction by means of an alloy-conversion reaction mechanism, which can significantly improve the initial charge and discharge efficiency of the lithium-ion battery, increase the specific capacity of the negative electrode of the lithium-ion battery, increase the overall energy density of the lithium-ion battery, and simultaneously improve the cycle performance of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a negative electrode active material and its preparation, a negative electrode sheet and a lithium ion battery. Background Art

[0002] Since lithium (Li) has the lowest reduction potential and the smallest ionic radius, among many metal ion secondary batteries, lithium ion rechargeable batteries are considered to be the most promising metal ion secondary battery system to achieve high mass / volume energy density and power density. After nearly three decades of research, lithium ion rechargeable batteries have been widely used in daily life. Mobile phones and laptops use lithium ion batteries, which are commonly referred to as lithium batteries. Lithium ion batteries generally use materials containing lithium as electrodes and are the representative of modern high-performance batteries. In recent years, the rapid growth of the battery market requires commercial lithium ion batteries to develop in the direction of being lighter, thinner and cheaper. However, the current commercial lithium ion batteries have reached their theoretical limits (~250wh / kg and ~680mh / L). Because the graphite-based negative electrode has a low theoretical specific capacity (~372mAh / g) and volume capacity (~735mAh / cm 3 ) limits the further improvement of the energy density of commercial LIBs. Then, the innovation of lithium-ion battery materials, including positive and negative electrodes, is mainly focused on improving the energy density of next-generation lithium-ion batteries to meet the needs of various applications.

[0003] Among the negative electrode materials for lithium-ion batteries, lead-based negative electrode materials have great development potential. The theoretical specific capacity of single lead is 550 mAh / g, which is far more than the theoretical specific capacity of graphite of 372 mAh / g. In addition, lead is an abundant earth element with low price. Thanks to the market of lead-acid batteries, the lead element has established a complete supply chain. Therefore, lead-based materials have broad prospects as advanced negative electrode materials after proper processing and recycling, and are worthy of further study. However, lead-based negative electrodes have a great problem in practical applications, that is, excessive expansion leads to specific capacity attenuation. Therefore, it is necessary to provide a lithium-ion battery negative electrode material and a lithium-ion battery to solve the above-mentioned problems in the prior art. Summary of the invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a negative electrode active material and its preparation, a negative electrode sheet and a lithium ion battery. The chemical composition of a negative electrode active material of the present invention is Pb w Sn x M y O z; wherein M is one or two of vanadium, chromium, carbon, manganese, sulfur, iron, phosphorus, niobium, antimony, and cobalt; the molar number of w is 1-3; the molar number of x is 0 or 1; the molar number of y is 1-5; the molar number of z is 1-8; Pb or Sn exists in the form of ions in Pb w Sn x M y O z The negative electrode active material has a high theoretical specific capacity and a fast charge and discharge mechanism because it can undergo alloy conversion reaction with lithium ions. Pb reacts with lithium ions to store lithium at a relatively low voltage, so that the negative electrode active material has a relatively low operating voltage and performs lithium storage reaction by alloy-conversion reaction mechanism. The voltage platform of the negative electrode active material during the charge and discharge process is 0.2v-0.7v. The negative electrode active material can significantly improve the initial charge and discharge efficiency of lithium-ion batteries, improve the specific capacity of the negative electrode of lithium-ion batteries, improve the overall energy density of lithium-ion batteries, and improve the cycle performance of batteries.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] The first object of the present invention is to provide a negative electrode active material, the chemical composition of the negative electrode active material is Pb w Sn x M y O z ,

[0007] The M is one or two of vanadium, chromium, carbon, manganese, sulfur, iron, phosphorus, niobium, antimony and cobalt, the molar number of w is 1-3; the molar number of x is 0-1; the molar number of y is 1-5; and the molar number of z is 1-8.

[0008] In one embodiment of the present invention, the mass fraction of the tin element in the negative electrode active material of the high specific capacity and low voltage platform lithium ion battery is 0%-20%.

[0009] In one embodiment of the present invention, the mass fraction of oxygen in the negative electrode active material of the high specific capacity and low voltage platform lithium ion battery is less than 50%.

[0010] In one embodiment of the present invention, the particle size of the negative electrode active material is between 10 nm and 50 μm.

[0011] A second object of the present invention is to provide a method for preparing a negative electrode active material, comprising the following steps:

[0012] (1) mixing a lead compound and an M compound, or mixing a lead compound, a tin compound and an M compound to obtain a mixture;

[0013] (2) smelting and post-treating the mixture prepared in step (1) to obtain a crude product;

[0014] (3) Grinding the crude product obtained in step (2) to obtain a negative electrode active material.

[0015] In one embodiment of the present invention, in step (1), the molar ratio of the lead compound to the M compound is 1-3:1-5, or the molar ratio of the lead compound, the tin compound and the M compound is 1-3:1:1-5.

[0016] In one embodiment of the present invention, in step (1), the lead compound is selected from one of lead carbonate, lead chloride, lead nitrate, lead dioxide and lead tetroxide;

[0017] The tin compound is selected from one of tin dioxide and tin trioxide;

[0018] In one embodiment of the present invention, in step (1), the other compound is selected from one or more of ammonium phosphate, ammonium hydrogen phosphate, calcium phosphate, sulfur trioxide, nitrogen dioxide, antimony trioxide, antimony pentafluoride, potassium pyroantimonate, and sodium pyroantimonate.

[0019] In one embodiment of the present invention, in step (2), during the smelting process, the smelting temperature is 800-1200° C. and the smelting time is 3-5 h.

[0020] In one embodiment of the present invention, in step (2), the post-treatment is a cooling treatment.

[0021] The third object of the present invention is to provide a negative electrode sheet, wherein the negative electrode sheet comprises the negative electrode active material.

[0022] In one embodiment of the present invention, the negative electrode sheet further includes a solid electrolyte, a conductive agent and a negative plate carrier.

[0023] A fourth object of the present invention is to provide a lithium-ion battery comprising the negative electrode sheet.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The lithium ion battery prepared by the negative electrode active material of the present invention has the advantages of high specific capacity and low voltage platform, can significantly improve the initial charge and discharge efficiency of the negative electrode material, increase the specific capacity of the negative electrode of the lithium ion battery, and improve the cycle performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the charge and discharge curve of the button-type battery prepared in Example 1 of the present invention;

[0027] Figure 2 This is a cycle performance curve of the button battery prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The present invention provides a negative electrode active material, the chemical composition of the negative electrode active material is Pb w Sn x M y O z ,

[0029] The M is one or two of vanadium, chromium, carbon, manganese, sulfur, iron, phosphorus, niobium, antimony and cobalt, the molar number of w is 1-3; the molar number of x is 0 or 1; the molar number of y is 1-5; and the molar number of z is 1-8.

[0030] In one embodiment of the present invention, the mass fraction of the tin element in the negative electrode active material of the high specific capacity and low voltage platform lithium ion battery is 0%-20%.

[0031] In one embodiment of the present invention, the mass fraction of oxygen in the negative electrode active material of the high specific capacity and low voltage platform lithium ion battery is less than 50%.

[0032] In one embodiment of the present invention, the particle size of the negative electrode active material is between 10 nm and 50 μm.

[0033] The present invention provides a method for preparing a negative electrode active material, comprising the following steps:

[0034] (1) mixing a lead compound and an M compound, or mixing a lead compound, a tin compound and an M compound to obtain a mixture;

[0035] (2) smelting and post-treating the mixture prepared in step (1) to obtain a crude product;

[0036] (3) Grinding the crude product obtained in step (2) to obtain a negative electrode active material.

[0037] In one embodiment of the present invention, in step (1), the molar ratio of the lead compound to the M compound is 1-3:1-5, or the molar ratio of the lead compound, the tin compound and the M compound is 1-3:1:1-5.

[0038] In one embodiment of the present invention, in step (1), the lead compound is selected from one of lead carbonate, lead chloride, lead nitrate, lead dioxide and lead tetroxide;

[0039] The tin compound is selected from one of tin dioxide and tin trioxide;

[0040] In one embodiment of the present invention, in step (1), the other compound is selected from one or more of ammonium phosphate, ammonium hydrogen phosphate, calcium phosphate, sulfur trioxide, nitrogen dioxide, antimony trioxide, antimony pentafluoride, potassium pyroantimonate, and sodium pyroantimonate.

[0041] In one embodiment of the present invention, in step (2), during the smelting process, the smelting temperature is 800-1200° C. and the smelting time is 3-5 h.

[0042] In one embodiment of the present invention, in step (2), the post-treatment is a cooling treatment.

[0043] The present invention provides a negative electrode sheet, wherein the negative electrode sheet comprises the negative electrode active material.

[0044] In one embodiment of the present invention, the negative electrode sheet further includes a solid electrolyte, a conductive agent and a negative plate carrier.

[0045] The present invention provides a lithium ion battery, which comprises the negative electrode sheet.

[0046] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] In the following examples, unless otherwise specified, all reagents used are commercially available reagents; all detection means and methods are conventional detection means and methods in the art.

[0048] Example 1

[0049] Pb 2 SnSbO 6.5 Compounds using PbO, SnO 2 , Sb 2 O 3 The materials were batched (molar ratio was 1:1:1), and after the materials were loaded into the melting crucible, the power was turned on to increase the temperature from room temperature to 925°C, and the temperature was kept at 925°C for 5 hours, and then the temperature was naturally lowered to room temperature;

[0050] Pb after smelting 2 SnSbO 6.5 The compound was collected with a particle size of 50 μm and ground into fine powder;

[0051] Making a button cell, using the active material prepared above to make a button cell;

[0052] The proportion is: active material accounts for 70% of the total material weight, 10% CMC, and 20% carbon black conductive agent.

[0053] The negative electrode carrier is copper foil.

[0054] The electrolyte system is ethylene carbonate EC: ethyl methyl carbonate EMC: dimethyl carbonate DMC = 1:1:1, 1M LiPF 6 .

[0055] The counter electrode is a lithium metal sheet.

[0056] The charge and discharge curves of the button cell prepared in this embodiment are as follows: Figure 1 As shown, the cycle performance curve is as follows Figure 2 shown.

[0057] Example 2

[0058] Pb 3 (PO 4 ) 2 Compound using PbSO 4 、NaH 2 PO 4 After the materials are batched (molar ratio is 1:1), they are loaded into the melting crucible, and the power is turned on to raise the temperature from room temperature to 1000°C, and the temperature is kept at 3h for melting, and then the temperature is naturally lowered to room temperature;

[0059] Pb after smelting 3 (PO 4 ) 2 The compound was collected with a particle size of 100 nm and ground into fine powder;

[0060] Making a button cell, using the active material prepared above to make a button cell;

[0061] The proportion is: active material accounts for 70% of the total material weight, 10% CMC, and 20% carbon black conductive agent.

[0062] The negative electrode carrier is copper foil.

[0063] The electrolyte system is ethylene carbonate EC: ethyl methyl carbonate EMC: dimethyl carbonate DMC = 1:1:1, 1M LiPF 6 .

[0064] The counter electrode is a lithium metal sheet.

[0065] Example 3

[0066] PbO compounds use PbCO 3 , P 2 O 5 After the materials are batched (molar ratio is 3:5), they are loaded into the smelting crucible, and the power is turned on to raise the temperature from room temperature to 1200°C, and the smelting temperature is kept at 3h for smelting, and then the temperature is naturally lowered to room temperature;

[0067] The smelted PbO compound is collected with a particle size of 100 nm and ground into fine powder;

[0068] Making a button cell, using the active material prepared above to make a button cell;

[0069] The proportion is: active material accounts for 70% of the total material weight, 10% CMC, and 20% carbon black conductive agent.

[0070] The negative electrode carrier is copper foil.

[0071] The electrolyte system is ethylene carbonate EC: ethyl methyl carbonate EMC: dimethyl carbonate DMC = 1:1:1, 1M LiPF 6 .

[0072] The counter electrode is a lithium metal sheet.

[0073] Example 4

[0074] PbO 2 Compounds using PbCl 4 , Ca 3 (PO 4 ) 2 After the materials are batched (molar ratio is 2:4), they are loaded into the smelting crucible, and the power is turned on to raise the temperature from room temperature to 1200°C, and the temperature is kept at 3h for smelting, and then the temperature is naturally lowered to room temperature;

[0075] PbO after smelting 2 The compound was collected with a particle size of 100 nm and ground into fine powder;

[0076] Making a button cell, using the active material prepared above to make a button cell;

[0077] The proportion is: active material accounts for 70% of the total material weight, 10% CMC, and 20% carbon black conductive agent.

[0078] The negative electrode carrier is copper foil.

[0079] The electrolyte system is ethylene carbonate EC: ethyl methyl carbonate EMC: dimethyl carbonate DMC = 1:1:1, 1M LiPF 6 .

[0080] The counter electrode is a lithium metal sheet.

[0081] Example 5

[0082] Pb 2 SnSbO 6.5 Compounds using PbCl 4 SnO 2 , Sb2 O 5 The materials were batched (molar ratio was 1:1:5), and after the materials were loaded into the smelting crucible, the power was turned on to raise the temperature from room temperature, the smelting temperature was 1200°C, and the temperature was kept for 4 hours for smelting, and then the temperature was naturally cooled to room temperature;

[0083] Pb after smelting 2 SnSbO 6.5 The compound was collected with a particle size of 100 nm and ground into fine powder;

[0084] Making a button cell, using the active material prepared above to make a button cell;

[0085] The proportion is: active material accounts for 70% of the total material weight, 10% CMC, and 20% carbon black conductive agent.

[0086] The negative electrode carrier is copper foil.

[0087] The electrolyte system is ethylene carbonate EC: ethyl methyl carbonate EMC: dimethyl carbonate DMC = 1:1:1, 1M LiPF 6 .

[0088] The counter electrode is a lithium metal sheet.

[0089] Example 6

[0090] Pb 2 SnSbO 6.5 Compounds using PbCl 4 SnO 2 、KSb(OH) 6 The materials were batched (molar ratio was 3:1:5), and after the materials were loaded into the smelting crucible, the power was turned on to increase the temperature from room temperature to 1200°C, and the temperature was kept at 5 hours for smelting, and then the temperature was naturally cooled to room temperature;

[0091] Pb after smelting 2 SnSbO 6.5 The compound was collected with a particle size of 100 nm and ground into fine powder;

[0092] Making a button cell, using the active material prepared above to make a button cell;

[0093] The proportion is: active material accounts for 70% of the total material weight, 10% CMC, and 20% carbon black conductive agent.

[0094] The negative electrode carrier is copper foil.

[0095] The electrolyte system is ethylene carbonate EC: ethyl methyl carbonate EMC: dimethyl carbonate DMC = 1:1:1, 1M LiPF6 .

[0096] The counter electrode is a lithium metal sheet.

[0097] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A negative electrode active material, characterized in that: The chemical composition of the negative electrode active material is Pb w Sn x M y O z , The M is one or two of vanadium, chromium, carbon, manganese, sulfur, iron, phosphorus, antimony, and cobalt; the molar number of w is 1-3; the molar number of x is 0 or 1; the molar number of y is 1-5; and the molar number of z is 1-8; Pb or Sn exists in the form of ions in Pb w Sn x M y O z middle; The negative electrode active material undergoes an alloy conversion reaction with lithium ions and has a high theoretical specific capacity and a fast charge and discharge mechanism.

2. A negative electrode active material according to claim 1, characterized in that: The particle size of the negative electrode active material is between 10 nm and 50 μm.

3. A method for preparing a negative electrode active material according to any one of claims 1 to 2, characterized in that: The following steps are involved: (1) mixing a lead compound and an M compound, or mixing a lead compound, a tin compound and an M compound to obtain a mixture; (2) smelting the mixture prepared in step (1) and then post-treating it to obtain a crude product; (3) Grinding the crude product obtained in step (2) to obtain a negative electrode active material.

4. The method for preparing a negative electrode active material according to claim 3, characterized in that: In step (1), the molar ratio of the lead compound to the M compound is 1-3:1-5, or the molar ratio of the lead compound, the tin compound and the M compound is 1-3:1:1-5.

5. The method for preparing a negative electrode active material according to claim 3, characterized in that: In step (1), the lead compound is selected from one of lead carbonate, lead chloride, lead nitrate, lead dioxide and lead tetroxide.

6. The method for preparing a negative electrode active material according to claim 3, characterized in that: In step (1), the tin compound is selected from tin dioxide and tin trioxide.

7. The method for preparing a negative electrode active material according to claim 3, characterized in that: In step (2), during the smelting process, the smelting temperature is 700-1200° C. and the smelting time is 3-5 h.

8. A negative electrode sheet, characterized in that: The negative electrode sheet contains the negative electrode active material according to any one of claims 1-2.

9. A lithium ion battery, characterized in that: The lithium-ion battery comprises the negative electrode sheet according to claim 8.

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