Current collector, electrode plate and lithium battery

Abstract

The utility model provides a current collector, an electrode plate and a lithium battery. The current collector comprises a thin film base material and a metal structure, the thin film base material is made of a high polymer material, and the metal structure is provided with a first metal layer and a second metal layer which are formed on the thin film base material; a middle layer is arranged between the first metal layer and the second metal layer; the intermediate layer is configured to adapt to the external temperature to adjust the resistance value of the intermediate layer and correspondingly switch the first metal layer and the second metal layer to a parallel connection conduction state or a disconnection state; the resistance value of the metal layers can be flexibly adjusted, the resistance value of the middle layer is reduced when the temperature is high, so that the two metal layers are conducted in parallel to correspondingly reduce the internal resistance of the whole metal structure and reduce heating during charging and discharging, and the resistance value of the middle layer is increased when the temperature is high. The internal resistance of the whole metal structure is correspondingly increased by disconnecting the two metal layers, and the heating during charging and discharging is increased, so that the metal structure is flexibly and efficiently adapted to various temperature environments.

Description

Technical Field

[0001] The utility model relates to the technical field of new energy batteries, and in particular to a current collector, an electrode sheet and a lithium battery. Background Art

[0002] Secondary batteries, also known as rechargeable batteries or storage batteries, refer to batteries that can be recharged to activate the active materials and continue to be used after the battery is discharged. Generally, the optimal operating temperature of secondary batteries is 5-40°C, especially at 20-25°C. This is because low temperatures may cause problems such as electrolyte freezing, lithium crystal precipitation, reduced discharge capacity, and increased internal resistance. High temperatures may shorten the service life of the battery and even cause thermal runaway, greatly affecting the safety of electricity use. At present, BMS management is usually used for heating or heat dissipation to manage the battery temperature, but it is still difficult to actively debug and control the battery's own temperature, so it cannot adapt to the external environment. Utility Model Content

[0003] In view of this, the purpose of the present invention is to provide a current collector, an electrode sheet and a lithium battery to solve the above problems.

[0004] The utility model adopts the following scheme:

[0005] The present application provides a current collector, comprising a thin film substrate and a metal structure; the thin film substrate is composed of a polymer material, and the metal structure has a first metal layer and a second metal layer formed on the thin film substrate; an intermediate layer is provided between the first metal layer and the second metal layer; the intermediate layer is configured to be able to adapt to the external temperature to adjust its own resistance, corresponding to switching the first metal layer and the second metal layer to a parallel conduction or disconnection state.

[0006] As a further improvement, the intermediate layer is constructed as an NTC thermistor material, and the relationship between its resistance value and temperature change is: RT = RN expB (1 / T–1 / TN); wherein,

[0007] RT is the resistance value at temperature T (K);

[0008] RN is the resistance of the NTC thermistor at the rated temperature TN (K);

[0009] T is the specified temperature (K);

[0010] And, B=T1*T2 / (T2-T1)ln(RT1 / RT2).

[0011] As a further improvement, the NTC thermistor material is formed by coating two or more metal oxides of manganese, copper, silicon, cobalt, iron, nickel and zinc.

[0012] As a further improvement, an intermediate layer of thermosensitive material is formed between two metal layers by a coating process such as R2R vacuum coating, sputtering, or evaporation, and the intermediate layer has a negative temperature coefficient, so that its resistance value decreases as the temperature increases.

[0013] As a further improvement, when the temperature is higher than the set temperature, the resistance of the intermediate layer decreases, so that the first metal layer and the second metal layer are switched to a parallel conductive state to reduce the internal resistance and the heat generated during charging and discharging.

[0014] As a further improvement, when the temperature is lower than a set temperature, the resistance of the intermediate layer increases, so that the first metal layer and the second metal layer are switched to a disconnected state to increase the internal resistance and the heat generated during charging and discharging.

[0015] As a further improvement, the thicknesses of the first metal layer, the second metal layer and the intermediate layer can be adjusted to a range that is adaptive to the external temperature; and the film substrate is a polymer film material of PET, PP, PI, LCP, or COP, and its thickness is 1-50um.

[0016] As a further improvement, one of the first metal layer, the second metal layer and the associated intermediate layer is arranged on the upper surface of the film substrate, and another of the first metal layer, the second metal layer and the associated intermediate layer is symmetrically arranged on the lower surface of the film substrate.

[0017] The present application further provides an electrode sheet, comprising active material layers stacked in sequence, and the current collector as described above.

[0018] The present application also provides a lithium battery, including a cathode electrode sheet, an anode electrode sheet, a separator and an electrolyte, wherein the cathode electrode sheet is configured as the electrode sheet described above.

[0019] By adopting the above technical solution, the utility model can achieve the following technical effects:

[0020] The current collector of the present application, through the intermediate layer provided between the first metal layer and the second metal layer, allows the intermediate layer to adapt to the external temperature to adjust its own resistance accordingly, so that the two metal layers can switch freely between the parallel conduction and disconnection states following the temperature change, and can flexibly adjust the resistance of the metal layer. When the temperature is high, the resistance value of the intermediate layer is reduced, and the two metal layers are connected in parallel to reduce the internal resistance of the entire metal structure and reduce the heat generated during charging and discharging. When the temperature is high, the resistance value of the intermediate layer is increased, and the internal resistance of the entire metal structure is increased by disconnecting the two metal layers, and the heat generated during charging and discharging is increased, thereby flexibly and efficiently adapting to various temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of a current collector according to an embodiment of the utility model;

[0022] Figure 2 It is a cross-sectional schematic diagram of a current collector according to an embodiment of the utility model;

[0023] Figure 3 This is a scanning electron microscope image of a current collector according to an embodiment of the present invention.

[0024] Icon: 1-film substrate; 2-first metal layer; 3-second metal layer; 4-intermediate layer. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the utility model. Therefore, the following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the utility model for which protection is sought, but merely represents the selected embodiments of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the utility model.

[0026] Example

[0027] Combination Figures 1 to 3 , this embodiment provides a current collector, including a film substrate 1 and a metal structure. The film substrate 1 is made of a polymer material, and the metal structure has a first metal layer 2 and a second metal layer 3 formed on the film substrate 1. An intermediate layer 4 is provided between the first metal layer 2 and the second metal layer 3. The intermediate layer 4 is configured to adjust its resistance value adaptively to the external temperature, corresponding to switching the first metal layer 2 and the second metal layer 3 to a parallel conduction state or a disconnection state.

[0028] The current collector mentioned above is provided with an intermediate layer 4 between the first metal layer 2 and the second metal layer 3, so that the intermediate layer 4 can adapt to the external temperature to adjust its own resistance accordingly, so that the two metal layers can switch freely between the parallel conduction and disconnection states following the temperature change, and the resistance of the metal layer can be flexibly adjusted. When the temperature is high, the resistance value of the intermediate layer 4 is reduced, and the internal resistance of the entire metal structure is reduced by connecting the two metal layers in parallel, thereby reducing the heat generated during charging and discharging. When the temperature is high, the resistance value of the intermediate layer 4 is increased, and the internal resistance of the entire metal structure is increased by disconnecting the two metal layers, thereby increasing the heat generated during charging and discharging, thereby flexibly and efficiently adapting to various temperature environments.

[0029] In this embodiment, the intermediate layer 4 is constructed as an NTC (negative temperature coefficient) thermistor material, and the relationship between its resistance value and temperature change is: RT = RN expB (1 / T–1 / TN). Wherein, RT is the resistance value at temperature T (K); RN is the resistance value of the NTC thermistor at rated temperature TN (K); T is the specified temperature (K); B = T1*T2 / (T2-T1)ln(RT1 / RT2). In the above, the resistance value of the intermediate layer 4 is exponentially related to the rated resistance value of the NTC thermistor, and further temperature changes are performed so that the NTC thermistor can adaptively adjust the change within the specified temperature range.

[0030] In this embodiment, the NTC thermistor material is formed by coating two or more metal oxides of manganese, copper, silicon, cobalt, iron, nickel, and zinc. Specifically, the intermediate layer 4 of the thermosensitive material formed between the two metal layers is manufactured by a coating process such as R2R vacuum coating, sputtering, or evaporation, and the intermediate layer 4 has a negative temperature coefficient, so that the resistance value decreases as the temperature increases.

[0031] When the temperature is higher than the set temperature, the resistance of the intermediate layer 4 decreases, so that the first metal layer 2 and the second metal layer 3 are switched to a parallel conductive state to reduce the internal resistance and heat generation during charging and discharging. At this time, the parallel conduction of the first metal layer 2 and the second metal layer 3 reduces the internal resistance of the entire metal structure, and after the current is passed, the heat is smaller due to the small resistance.

[0032] When the temperature is lower than the set temperature, the resistance of the intermediate layer 4 increases, so that the first metal layer 2 and the second metal layer 3 are switched to a disconnected state to increase the internal resistance and the heat generated during charging and discharging. At this time, the first metal layer 2 and the second metal layer 3 are disconnected, so that the internal resistance of the metal structure is the resistance of the first metal layer 2 or the resistance of the second metal layer 3. When the current is passed, the heat is greater due to the large resistance.

[0033] In this embodiment, the thickness of the first metal layer 2, the second metal layer 3 and the intermediate layer 4 can be adjusted to be within a range that is adaptive to the external temperature. Thus, by adjusting the thickness of the metal layer and the intermediate layer 4, the adaptive temperature range can be adjusted accordingly.

[0034] In this embodiment, the film substrate 1 is a polymer film material of PET, PP, PI, LCP, or COP, and its thickness is 1-50um. Preferably, the film substrate 1 is a polyimide PI film substrate 1, and its thickness is greater than each metal layer, and the thickness of the intermediate layer 4 is less than each metal layer.

[0035] like Figure 2 and Figure 3 As shown, in this embodiment, one of the first metal layer 2, the second metal layer 3 and the associated intermediate layer 4 is disposed on the upper surface of the film substrate 1, and another of the first metal layer 2, the second metal layer 3 and the associated intermediate layer 4 is symmetrically disposed on the lower surface of the film substrate 1. Thus, metal structures can be efficiently formed on both sides of the polyimide PI film substrate 1, greatly improving the efficiency of the product.

[0036] In a preferred embodiment, a 50nm thick copper layer (first metal layer 2) is sputtered on a 6μm thick PP film (polymer base film 1) in an argon atmosphere using a magnetron sputtering device with pure copper as the target. Subsequently, a 20nm thick Ni-Mn-Cu-O ternary oxide layer is sputtered on the surface of the sputtered copper layer in an oxygen atmosphere using a Ni-Mn-Cu-O alloy as the target, wherein the atomic ratio of Ni:Mn:Cu in the alloy target is 7:2:3, to obtain a negative temperature coefficient thermistor thin film layer (intermediate layer 4). Finally, a 1μm thick copper layer (second metal layer 3) is electroplated on the surface of the composite film through an electroplating process; thereby a composite current collector with intelligently adjustable resistance is obtained.

[0037] Among them, this embodiment further provides an electrode sheet, including active material layers stacked in sequence, and the current collector as described above.

[0038] Among them, this embodiment also provides a lithium battery, including a cathode electrode sheet, an anode electrode sheet, a separator and an electrolyte, and the cathode electrode sheet is configured as the electrode sheet mentioned above.

[0039] The above are only preferred implementations of the present utility model. The protection scope of the present utility model is not limited to the above embodiments. All technical solutions under the concept of the present utility model belong to the protection scope of the present utility model.

Claims

1. A current collector, characterized in that: It includes a thin film substrate and a metal structure; the metal structure has a first metal layer and a second metal layer formed on the thin film substrate; an intermediate layer is provided between the first metal layer and the second metal layer; the intermediate layer is configured to be able to adjust its own resistance value adaptively according to the external temperature, correspondingly switching the first metal layer and the second metal layer to a parallel conduction or disconnection state.

2. The current collector according to claim 1, characterized in that: The intermediate layer is constructed as an NTC thermistor material, and the relationship between its resistance value and temperature change is: RT = RN expB (1 / T–1 / TN); wherein, RT is the resistance value at temperature T (K); RN is the resistance of the NTC thermistor at the rated temperature TN (K); T is the specified temperature (K); And, B=T1*T2 / (T2-T1)ln(RT1 / RT2).

3. The current collector according to claim 2, characterized in that: An intermediate layer of a thermosensitive material formed between two metal layers is manufactured by a coating process such as R2R vacuum coating, sputtering, or evaporation, and the intermediate layer has a negative temperature coefficient characteristic, so that its resistance value decreases as the temperature increases.

4. The current collector according to claim 3, characterized in that: When the temperature is higher than the set temperature, the resistance of the intermediate layer decreases, so that the first metal layer and the second metal layer are switched to a parallel conductive state to reduce the internal resistance and the heat generated during charging and discharging.

5. The current collector according to claim 3, characterized in that: When the temperature is lower than the set temperature, the resistance of the intermediate layer increases, so that the first metal layer and the second metal layer are switched to a disconnected state to increase the internal resistance and heat generation during charging and discharging.

6. The current collector according to claim 1, characterized in that: The thicknesses of the first metal layer, the second metal layer and the intermediate layer can be adjusted to be within a range that is adaptive to the external temperature; and the film substrate is a polymer film material of PET, PP, PI, LCP, or COP, and its thickness is 1-50um.

7. The current collector according to claim 1, characterized in that: One of the first metal layer, the second metal layer and the associated intermediate layer is disposed on the upper surface of the film substrate, and another of the first metal layer, the second metal layer and the associated intermediate layer is symmetrically disposed on the lower surface of the film substrate.

8. An electrode sheet, characterized in that: The invention comprises active material layers stacked in sequence, and a current collector as claimed in any one of claims 1 to 7.

9. A lithium battery, characterized in that: It comprises a cathode electrode sheet, an anode electrode sheet, a separator and an electrolyte, wherein the cathode electrode sheet is configured as the electrode sheet as claimed in claim 8.

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