Low temperature lithium ion anode structure

Abstract

The utility model relates to the field of lithium ion battery especially, relate to a kind of low temperature lithium ion negative electrode structure;Including: first lithium intercalation layer, intermediate layer, second lithium intercalation layer and current collector;Wherein, intermediate layer includes: by the interlaced formation of several ribbons ribbons area and the grid area formed between adjacent ribbons;The utility model's negative electrode structure, Li+ is intercalated lithium in second lithium intercalation layer during low temperature charging, and Li+ is transferred to first lithium intercalation layer by intermediate layer ribbons, Li+ rapidly longitudinal transmission, form line-surface three-dimensional network;In the later stage of charging, Li+ is transferred to intermediate layer grid area by line-surface three-dimensional network;Line-surface three-dimensional network and grid area form voltage difference, help Li+ overcome interlayer van der waals force potential barrier, diffuse between graphite;When local Li+ of grid area is supersaturated, Li+ can be transferred from grid area to ribbons, avoid forming lithium dendrite.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion batteries, and in particular to a low-temperature lithium-ion anode structure. Background Technology

[0002] Lithium-ion batteries, as the core of today's energy storage technology, play an irreplaceable role in electric vehicles, portable electronic devices, and renewable energy storage. However, insufficient low-temperature performance has always been one of the key bottlenecks restricting their widespread application. At low temperatures, lithium ions need to overcome a higher energy barrier when crossing the solid electrolyte interphase (SEI) film, leading to a significant increase in charge transfer resistance (Rct). The diffusion coefficient of lithium ions in electrode materials (DLi+) is closely related to temperature. Taking graphite anodes as an example, their lithium-ion diffusion coefficient increases from 10 at 25℃. -10 cm 2 / s drops to -20℃ 10 -13 cm 2 / s below. Meanwhile, as the temperature decreases, the lithium intercalation potential of graphite (approximately 0.1V vs. Li) decreases. + / Li) and lithium deposition potential (0V vs. Li) + The safety window between Li and Li gradually narrows. When the polarization voltage exceeds this critical value, lithium ions tend to be reduced to metallic lithium on the negative electrode surface rather than embedded between the graphite layers. Therefore, there is an urgent need for a negative electrode structure suitable for low-temperature environments. Utility Model Content

[0003] The purpose of this invention is to address the shortcomings of existing technologies by providing a low-temperature lithium-ion anode structure.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0005] A low-temperature lithium-ion anode structure is provided, comprising: a first lithium intercalation layer, an intermediate layer, a second lithium intercalation layer, and a current collector;

[0006] The intermediate layer includes: a rib area formed by the interlacing of several ribs and a grid area formed between adjacent ribs.

[0007] Preferably, the proportion of the ribs in the intermediate layer is 10-30%.

[0008] Preferably, the shape of the grid area includes: triangle, rectangle, rhombus, and hexagon.

[0009] Preferably, in the intermediate layer, the ribs are hard carbon ribs, and the grid area is filled with graphite.

[0010] Preferably, the two ends of the plurality of ribs are in contact with the first lithium intercalation layer and the second lithium intercalation layer, respectively.

[0011] Preferably, the first lithium intercalation layer, the intermediate layer, and the second lithium intercalation layer form a three-dimensional network of lithium-ion diffusion channels.

[0012] Preferably, both the first lithium intercalation layer and the second lithium intercalation layer have active material regions distributed thereon.

[0013] More preferably, the active material in the active material region includes at least one of lithium titanate, niobium-based oxide, or copper-sulfur compound.

[0014] More preferably, in the first lithium intercalation layer and the second lithium intercalation layer, the proportion of the active material region is independently selected from 1-10%.

[0015] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0016] In the negative electrode structure of this invention, during low-temperature charging, Li+ is intercalated in the second lithium intercalation layer, and Li+ is transferred to the first lithium intercalation layer through the intermediate layer ribs. Li+ is rapidly transferred longitudinally, forming a line-plane three-dimensional network. In the middle and later stages of charging, Li+ is transferred to the intermediate layer grid region through the line-plane three-dimensional network. The line-plane three-dimensional network and the grid region form a voltage difference, which helps Li+ overcome the interlayer van der Waals force barrier and diffuse between graphite layers. When the grid region is locally oversaturated with Li+, Li+ can be transferred from the grid region to the ribs, avoiding the formation of lithium dendrites. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the basic structure of a low-temperature lithium-ion anode structure in one embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the basic structure of the intermediate layer in one embodiment of the present invention.

[0019] The reference numerals in the figure include:

[0020] First lithium intercalation layer 1; intermediate layer 2; rib 21; grid area 22; second lithium intercalation layer 3; current collector 4. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention.

[0024] Example

[0025] This embodiment provides a low-temperature lithium-ion anode structure, including: a first lithium intercalation layer 1, an intermediate layer 2, a second lithium intercalation layer 3, and a current collector 4; the current collector 4, the first lithium intercalation layer 1, the intermediate layer 2, and the second lithium intercalation layer 3 are arranged sequentially.

[0026] The intermediate layer 2 includes: a rib region formed by interlacing ribs 21 and a grid region 22 formed between adjacent ribs; the ribs 21 account for 20% of the total area, the grid region 22 is rectangular in shape, and the grid region 22 is filled with graphite; both the first lithium intercalation layer 1 and the second lithium intercalation layer 3 have active material regions distributed therein, and the active material in the active material regions is lithium titanate; in the first lithium intercalation layer 1, the active material region accounts for 2% of the total area; in the second lithium intercalation layer 3, the active material region accounts for 8% of the total area.

[0027] Detection Examples

[0028] The low-temperature lithium-ion anode structure of the embodiment was used in combination with the lithium iron phosphate cathode to make a soft-pack battery. A graphite anode was used as a comparison for battery performance testing. The results are shown in Table 1.

[0029] Table 1

[0030] room temperature capacity / mAh 1.216 1.256 -30℃ charging capacity / mAh 1.082 0.352 -30℃ discharge capacity / mAh 0.919 0.252 -30℃ volume retention rate 75.58％ 20.06％

[0031] The negative electrode structure of this invention exhibits significantly superior capacity retention compared to conventional negative electrodes at low temperatures. During low-temperature charging, Li+ is intercalated in the second lithium-intercalation layer, and then transferred to the first lithium-intercalation layer via the intermediate layer ribs. Li+ rapidly propagates longitudinally, forming a line-plane three-dimensional network. In the later stages of charging, Li+ is transferred to the intermediate layer grid region via the line-plane three-dimensional network. A voltage difference is created between the line-plane three-dimensional network and the grid region, helping Li+ overcome the interlayer van der Waals force barrier and diffuse between graphite layers. When localized Li+ oversaturation occurs in the grid region, Li+ can be transferred from the grid region to the ribs, preventing the formation of lithium dendrites.

[0032] The above description is only a preferred embodiment of the present utility model and does not limit the implementation method and protection scope of the present utility model. Those skilled in the art should realize that all solutions obtained by equivalent substitutions and obvious changes made based on the description and illustrations of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A low temperature lithium-ion anode structure, characterized by, include: The first lithium intercalation layer (1), the intermediate layer (2), the second lithium intercalation layer (3), and the current collector (4); the first lithium intercalation layer (1), the intermediate layer (2), and the second lithium intercalation layer (3) form a three-dimensional network of lithium-ion diffusion channels; The intermediate layer (2) includes: a rib area formed by the interlacing of several ribs (21) and a grid area (22) formed between adjacent ribs.

2. The cryogenic lithium-ion anode structure of claim 1, wherein, In the intermediate layer (2), the proportion of the ribs (21) is 10-30%.

3. The cryogenic lithium-ion anode structure of claim 1, wherein, The shapes of the grid area (22) include: triangle, rectangle, rhombus, and hexagon.

4. The cryogenic lithium-ion anode structure of claim 1, wherein, In the intermediate layer (2), the ribs (21) are hard carbon ribs, and the grid area (22) is filled with graphite.

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