Photothermal enhanced lithium ion adsorber for seawater lithium extraction, device and application

Abstract

The application discloses a photo-thermal enhanced lithium ion adsorber for seawater lithium extraction, which comprises a columnar core material and a shell layer coated on the side wall of the core material; the core material is a hydrophilic lithium ion adsorption nanofiber material, and the shell layer is a hydrophobic photo-thermal nanofiber material. The application further discloses a photo-thermal enhanced lithium ion adsorption device comprising the photo-thermal enhanced lithium ion adsorber and a method for seawater lithium extraction based on the photo-thermal enhanced lithium ion adsorption device. The photo-thermal enhanced lithium ion adsorber and the device can use sunlight as the only energy source, and realize efficient, long-lasting and low-energy-consumption seawater lithium extraction.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium ion adsorption, in particular to a photothermal enhanced lithium ion adsorber, device and application for extracting lithium from seawater. BACKGROUND

[0002] Lithium is a key component of lithium-ion batteries and is regarded as the "white oil" in the field of new energy. In recent years, with the wide application of lithium-ion batteries in portable electronic devices, electric vehicles and grid energy storage fields, the gap in lithium resource supply has been rapidly expanding. It is reported that there are more than 230 billion tons of undeveloped lithium resources in seawater, which is far more than the total amount of lithium resources on land (about 14 million tons), and is a treasure to be exploited and mined. However, due to the extremely low concentration of lithium ions (Li + ) in seawater (~0.2mg·L -1 ), and the presence of a large number of interfering ions (500-10000mg·L -1 ), efficient extraction of lithium from seawater is still a great challenge.

[0003] In recent years, methods for extracting lithium from seawater have emerged, including nanofiltration membrane separation, electrochemical extraction and lithium ion sieve adsorption. However, these existing seawater lithium extraction technologies have some problems, which largely limit their application.

[0004] For example, the Chinese patent document with publication number CN106925121A reports a positively charged nanofiltration membrane, which realizes efficient Li + / Mg 2+ separation, but the Li + / Na + selectivity of the nanofiltration membrane separation material is low, and there will still be high concentration of Na + impurities in the filtrate.

[0005] The Chinese patent document with publication number CN115386740A proposes a seawater lithium extraction device based on the principle of electrodialysis. Although electrochemical lithium extraction technology has excellent Li + / Na + and Li + / Mg 2+ selectivity, it usually requires an additional electrolyte environment and huge electrical energy consumption, and inevitably produces gaseous by-products.

[0006] The Chinese patent documents with publication numbers CN111282449A and CN114272888A report the preparation method of a composite material based on lithium ion sieve, which is used for seawater lithium extraction. The lithium ion sieve adsorption method can efficiently and selectively extract Li + from seawater, but is limited by the extremely low Li+ concentration, the adsorption rate is limited.

[0007] Although there are studies using chemical potential, electric field or pressure to drive, improve the local Li + concentration near the adsorption site of lithium ion sieve. + The enrichment method is relatively complex and high energy consumption. In addition, in the long-term use of lithium ion sieve, the gradually accumulated high concentration of interfering ions will exacerbate the concentration polarization and even form salt scale, which will damage its long-term adsorption performance.

[0008] Therefore, it is of great significance to develop an energy-saving method to efficiently and durably extract lithium ions from seawater. SUMMARY

[0009] The application provides a photothermal enhanced lithium ion adsorber, device and application for seawater lithium extraction, which can use sunlight as the only energy source to achieve efficient, durable and low-energy seawater lithium extraction.

[0010] The technical scheme of the application is as follows:

[0011] A photothermal enhanced lithium ion adsorber for seawater lithium extraction, comprising a columnar core material and a shell layer wrapped outside the side wall of the core material; the core material is a hydrophilic lithium ion adsorption nanofiber material, and the shell layer is a hydrophobic photothermal nanofiber material.

[0012] The core material is wound into a columnar shape by a hydrophilic lithium ion adsorption nanofiber film. The cross-sectional diameter of the core material is 0.2-4.6 cm, the average fiber diameter of the hydrophilic lithium ion adsorption nanofiber is 100-1200 nm; the thickness of the shell layer is 50-2000 μm, and the average fiber diameter of the hydrophobic photothermal nanofiber is 100-5000 nm.

[0013] Further preferably, the thickness of the shell layer is 100-600 μm; and more preferably, 300-500 μm.

[0014] Preferably, the hydrophilic lithium ion adsorption nanofiber is a hydrophilic polymer fiber coated with lithium ion sieve.

[0015] The hydrophilic polymer is at least one of polyacrylonitrile, polyether sulfone, polyvinyl alcohol and cellulose acetate; and the lithium ion sieve is H 1.33 Mn 1.67 O4, H 1.6 Mn 1.6 O4, H2TiO3, H4Ti5O 12at least one of the lithium ion adsorption nanofiber and the lambda-MnO2 (see the literature: Progress in Materials Science, 2016, 84, 276-313).

[0016] The mass ratio of the lithium ion sieve and the hydrophilic polymer in the hydrophilic lithium ion adsorption nanofiber is 1:1.0-4.5.

[0017] Preferably, the hydrophobic photothermal nanofiber is a hydrophobic polymer fiber coated with a photothermal conversion material.

[0018] The hydrophobic polymer is at least one of polyurethane, polyvinylidene fluoride, polymethyl methacrylate, polylactic acid and polystyrene; and the photothermal conversion material is at least one of graphene, carbon nanotube, carbon black, graphite and ferroferric oxide.

[0019] The mass ratio of the photothermal conversion material and the hydrophobic polymer in the hydrophobic photothermal nanofiber is 1:0.2-3.0.

[0020] Preferably, the preparation method of the photothermal enhanced lithium ion adsorber comprises:

[0021] (1) dissolving and uniformly mixing the hydrophilic polymer and the lithium ion sieve to obtain spinning solution A; dissolving and uniformly mixing the hydrophobic polymer and the photothermal conversion material to obtain spinning solution B;

[0022] (2) electrospinning the spinning solution A on a flat collector to obtain a hydrophilic lithium ion adsorption nanofiber mat, and cutting and winding the nanofiber mat into a column; loading the hydrophobic photothermal nanofiber electrospun from the spinning solution B on the side wall of the continuously rotating hydrophilic fiber column to construct a photothermal enhanced lithium ion adsorber.

[0023] The mass fraction of the hydrophilic polymer in the spinning solution A is 5-20%; and the mass fraction of the hydrophobic polymer in the spinning solution B is 5-30%.

[0024] The application further provides a photothermal enhanced lithium ion adsorption device for seawater lithium extraction, comprising a feed liquid tank, a through hole is formed in the side wall of the feed liquid tank, the through hole is in communication with one end of the photothermal enhanced lithium ion adsorber, and the other end of the photothermal enhanced lithium ion adsorber is inclined to the bottom of the feed liquid tank.

[0025] In use, seawater is injected into the liquid tank of the light-heat enhanced lithium ion adsorption device. On the one hand, under the irradiation of sunlight, the shell of the light-heat enhanced lithium ion adsorber can promote the flow of seawater and the concentration of lithium ions in the hydrophilic core material through solar-driven light-heat evaporation; on the other hand, under the action of gravity, seawater will slowly filter out from the end of the hydrophilic core material along the hydrophilic core material. The light-heat enhanced lithium ion adsorption device ingeniously utilizes the synergy of gravity-driven water flow and solar-driven water evaporation, resulting in rapid replenishment-enhanced diffusion-high efficient enrichment of lithium ions in the light-heat enhanced lithium ion adsorption device, thereby realizing efficient, durable and low-energy consumption lithium ion adsorption.

[0026] Preferably, the angle between the length direction of the light-heat enhanced lithium ion adsorber and the liquid tank is 10-80°; further preferably 15-60°; further preferably 30-45°.

[0027] The application also provides a method for extracting lithium from seawater based on the light-heat enhanced lithium ion adsorption device, comprising:

[0028] Seawater is injected into the liquid tank, and under the irradiation of sunlight, lithium ions in seawater are adsorbed by the light-heat enhanced lithium ion adsorber.

[0029] After adsorption saturation, hydrochloric acid solution is used to desorb lithium ions from the light-heat enhanced lithium ion adsorber, and after desorption is completed, the light-heat enhanced lithium ion adsorption device is cleaned, completing the cyclic regeneration of the light-heat enhanced lithium ion adsorption device.

[0030] Preferably, the concentration of the hydrochloric acid solution is 0.1-2.0 mol·L -1 .

[0031] Compared with the prior art, the application has the following beneficial effects:

[0032] (1) The light-heat enhanced lithium ion adsorber with the inner layer of hydrophilic lithium ion adsorption nanofibers and the outer layer of hydrophobic light-heat nanofibers is prepared by sequential electrospinning and winding method. The hydrophilic nanofibers in the inner layer of the adsorber can provide a fast and continuous seawater flow channel, and the lithium ion sieve loaded thereon is responsible for selectively adsorbing Li + ; the hydrophobic nanofibers in the outer layer not only prevent the leakage of the inner layer flow water, but also promote the flow of seawater in the inner layer and the concentration of Li + through solar-driven light-heat evaporation.

[0033] (2) The light-heat enhanced lithium ion adsorption device has the ability of fast ion diffusion and high efficient ion concentration promoted by light-heat, which helps to improve the Li + adsorption performance of the adsorber. On the one hand, the light-heat promoted fast ion diffusion helps to Li +to obtain better adsorption efficiency; on the other hand, the ion concentration caused by high-efficiency photothermal evaporation can increase the Li + concentration near the adsorption sites, which provides a huge driving force for adsorption.

[0034] (3) The spatial configuration of the adsorber in the light-heat enhanced lithium ion adsorption device is regulated, and the concentrated interfering salt ions can be carried away by the water flow driven by gravity, which can eliminate the concentration difference polarization and even the scaling precipitation of high-concentration interfering ions in the photothermal evaporation process. Therefore, the adsorption device can maintain stable and long-lasting Li -1 adsorption performance even when the concentration of interfering salt ions in the lithium-containing solution is as high as 150 g·L + .

[0035] (4) The light-heat enhanced lithium ion adsorption device uses sunlight as the only energy source, and the power consumption in the adsorption process is extremely low. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a schematic diagram of the preparation process of the light-heat membrane adsorber; the light-heat enhanced lithium ion adsorber

[0037] Figure 2 is a photograph of the light-heat membrane adsorber and the lithium ion adsorption device;

[0038] Figure 3 is a schematic diagram of the light-heat enhanced Li + adsorption / desorption process driven by solar energy in the lithium ion adsorption device;

[0039] Figure 4 are scanning electron microscope photographs of the cross-sectional morphology and fiber morphology of the light-heat membrane adsorber, (a) is a scanning electron microscope photograph of the cross section of the light-heat membrane adsorber, (b) is a local enlarged view of (a), (c) is a scanning electron microscope photograph of the hydrophobic light-heat fiber, (d) is a local enlarged view of (c), (e) is a scanning electron microscope photograph of the hydrophilic lithium ion adsorption fiber, and (f) is a local enlarged view of (e);

[0040] Figure 5 is a photograph of the lithium ion adsorption device operating for 10 hours under solar irradiation from a lithium-containing solution containing 15wt% NaCl. DETAILED DESCRIPTION

[0041] The application will be further described in detail below in conjunction with the drawings and examples, and it should be pointed out that the following examples are intended to facilitate the understanding of the application and do not limit it in any way.

[0042] The hydrophilic polymer and lithium ion sieve are dissolved and mixed uniformly to obtain spinning solution A; the hydrophobic polymer and light-heat conversion material are dissolved and mixed uniformly to obtain spinning solution B.

[0043] The preparation method of the light-heat film adsorber in the application is as shown in Figure 1 The prepared spinning solution A is electrospun on a flat collector to produce a hydrophilic lithium ion adsorption nanofiber pad, and the lithium ion adsorption nanofiber pad is cut and wound into a column. Then, the hydrophobic light-heat nanofiber formed by electrospinning of the spinning solution B is loaded on the side wall of the continuously rotating hydrophilic fiber column to construct the light-heat film adsorber. The finally prepared light-heat film adsorber is a nanofiber column with a core-shell structure, the outer layer of which is a hydrophobic light-heat fiber, and the inner layer of which is a hydrophilic lithium ion adsorption fiber. The light-heat film adsorber is assembled into the feed liquid tank in an inclined downward spatial configuration to prepare a light-heat enhanced lithium ion adsorption device. The actual photos of the light-heat film adsorber (a) and the light-heat enhanced lithium ion adsorption device (b) are as shown in Figure 2 .

[0044] The solar-driven light-heat enhanced lithium ion adsorption device prepared in the application can be used for seawater lithium extraction. Therefore, the solar light can be used to drive the Li + adsorption / desorption experiment is a key experiment, and the specific experimental procedure is as shown in Figure 3 After adsorption saturation, pure water is used for washing, then hydrochloric acid solution is used for lithium desorption, and after desorption completion, pure water is used for cleaning to complete the cycle regeneration of the light-heat film adsorber. The evaporation rate, Li + adsorption rate, Li + adsorption capacity, ion adsorption efficiency and Li + adsorption energy consumption are important parameters for evaluating the device.

[0045] The evaporation rate is defined as the evaporation loss rate of the membrane adsorber under solar irradiation per unit area per unit time, and its unit is kg·m -2 ·h -1 , and the calculation formula is:

[0046]

[0047] Wherein, Δm ！ (g) is the evaporation loss of the membrane adsorber in the test time, Δt(h) is the test time, and S(m 2 ) is the projection area of the membrane adsorber under solar irradiation.

[0048] According to the mass of the filtrate collected at the end of the light-heat film adsorber and the residual Li + concentration collected after 1h of the start of the adsorption experiment, the Li + adsorption rate can be calculated, which is mg Li ·h -1 , and the calculation formula is:

[0049]

[0050] Among them, C 2！awat！r (mg·L -1 ) and C f (mg·L -1 ) are respectively Li in seawater + Concentration and Li in the liquid filtered from the end of the photothermal film adsorber + Concentration, Δm f (g) is the amount of liquid filtered out at the end of the photothermal film adsorber during the test time.

[0051] Based on the mass of the filtrate collected at the end of the membrane adsorber and the residual Li collected 10 hours after the start of the adsorption experiment... + The concentration of Li can be calculated. + Adsorption capacity, in mg Li The calculation formula is:

[0052] TC Li =C f！！d (Δm f +Δm ！ )-C f Δm f

[0053] Among them, C f！！d (mg·L -1 ) is Li in the feed liquid + concentration.

[0054] The adsorption efficiency (EE) of the evaporator for various ions in seawater M ,%) is calculated according to the following formula:

[0055]

[0056] Among them, C s！awat！r-M (mg·L -1 ) and C f-M (mg·L -1 ) are the concentrations of M ions in seawater and the liquid filtered out at the end of the photothermal membrane adsorber, respectively.

[0057] Lithium-ion adsorption device adsorbs Li under solar power. + In the experiment, only electrical energy was needed to transport seawater to the feed tank. The seawater then flowed into the photothermal film adsorber under gravity and achieved efficient adsorption under solar energy. Therefore, the photothermal film adsorber is used for Li + The electrical energy consumption (EC) of adsorption can be estimated using the following formula:

[0058]

[0059] Where H(m) is the vertical height of the photothermal film adsorber, g (approximately 9.8 N·kg)-1 ) is the gravitational constant, is the Li + adsorption efficiency.

[0060] For a 5 cm long light-heat film adsorber, it is calculated that its adsorption energy consumption for Li + in seawater is about 1.23 J·mgLi -1 .

[0061] Example 1

[0062] (1) The lithium manganese oxide H 1.6 Mn 1.6 O4(HMO, 1.05 g) was uniformly dispersed in DMF (16.05 mL) by ultrasonic, and PAN (polyacrylonitrile) (1.5 g) was added at 75°C to prepare a PAN / HMO solution; PVDF (1.0 g), Fe3O4nanoparticles (1.0 g) were dissolved in 6.0 mL of DMF at 75°C to prepare a uniform PVDF / Fe3O4mixed solution. All the above blended solutions need to be continuously stirred at 75°C in a magnetic stirrer for 6 h before use.

[0063] (2) The prepared PAN / HMO solution was electrospun on a flat collector to produce a PAN / HMO nanofiber mat with an average thickness of 98±6 μm (spinning speed: 0.8 mL·h -1 , applied voltage: 12.5 kV, electrospinning time: 4 h). The obtained PAN / HMO nanofiber mat was cut into a rectangle of 15 cm×11 cm and the 11 cm side was rolled into a PAN / HMO fiber column. The length of the fiber column was 15 cm and the cross-sectional diameter was 0.6 cm.

[0064] (3) Finally, the PVDF / Fe3O4solution was spun onto the side wall of the continuously rotating PAN / HMO fiber column to build a light-heat film adsorber under the conditions of a voltage of 7.5 kV and a spinning solution advancing speed of 0.8 mL·h -1 . The electrospinning time was controlled to be 80 min, the rotation speed of the PAN / HMO fiber column was controlled to be 5 rpm, and the thickness of the hydrophobic PVDF / Fe3O4fiber layer on the light-heat film adsorber was 317 μm.

[0065] (4) The hydrophilic nanofiber core of the light-heat film adsorber was fully wetted with ultrapure water, then the light-heat film adsorber with a length of 5 cm was inserted into the liquid tank (10.0 cm×5 cm×5 cm) with a 0.6 cm round hole in the side wall at an oblique downward 30°, and the gap between the light-heat film adsorber and the round hole was sealed with AB glue, to obtain a light-heat enhanced lithium ion adsorption device. The sealing of the AB glue not only fixes the spatial configuration of the light-heat film adsorber, but also prevents the liquid from leaking from the round hole of the liquid tank.

[0066] The cross-section morphology and fiber morphology of the photo-thermal membrane adsorber are shown in FIG. 1. The cross-section of the photo-thermal membrane adsorber shows a core-shell structure, the core layer is the hydrophilic PAN / HMO nanofiber, and the shell layer is the photo-thermal hydrophobic layer composed of PVDF / Fe304 nanofiber. There are many physical entanglement sites at the interface of the two layers of fibers, so that the core-shell double layer of the photo-thermal membrane adsorber closely adheres to each other at the interface. Figure 4

[0067] The evaporation rate of the photo-thermal enhanced lithium ion adsorption device prepared in Example 1 under sunlight irradiation is 3.51 kg·m -2 ·h -1 , and the Li + adsorption rate facing seawater is 2.52·10 -4 mg Li ·h -1 . In contrast, the evaporation rate of the adsorption device without sunlight irradiation is only 1.66 kg·m -2 ·h -1 , and the Li + adsorption rate facing seawater is 1.38·10 -4 mg Li ·h -1 .

[0068] The main ion concentrations of seawater before and after adsorption by the prepared adsorption device in Example 1 under sunlight irradiation are listed in Table 1. It can be calculated from the data in Table 1 that the adsorption device can efficiently capture nearly 99.3% of Li + in seawater, while almost no other interfering ions (such as Na + ~1.0%, Mg 2+ ~1.4%, K + ~1.1%, Ca 2+ ~3.4%) in seawater are captured, in addition, the Li + / Na + and Li + / Mg 2+ selectivity of the adsorption device is as high as 14042 and 9989, respectively.

[0069] Table 1 Main ion concentrations of seawater before and after adsorption by the prepared adsorption device in Example 1 under sunlight irradiation

[0070]

[0071]

[0072] Examples 2-4

[0073] ​On the basis of Example 1, the spinning time of the hydrophobic photothermal layer was adjusted to prepare a series of photothermal film adsorbers with different thicknesses of the hydrophobic photothermal layer. The adsorption devices were assembled and the evaporation rate and Li + adsorption rate were tested. The other experimental conditions were the same as in Example 1.

[0074] Table 2. Evaporation rate and Li + adsorption rate of the adsorption devices prepared in Examples 1-4 under solar irradiation

[0075]

[0076] From the test data in Table 2 above, it can be seen that the change in the thickness of the hydrophobic photothermal layer has a great influence on the evaporation performance and adsorption performance of the lithium ion adsorption device enhanced by photothermality.

[0077] Examples 5-7

[0078] On the basis of Example 1, the included angle of the photothermal film adsorber in the adsorption device was adjusted to be 15°, 45° and 60° downward. The Li + adsorption rate of the adsorption device facing seawater was tested. The other experimental conditions were the same as in Example 1.

[0079] Table 3. Li + adsorption rate of the adsorption devices prepared in Examples 1 and 5-7 under solar irradiation

[0080] Angle (°) Li + Adsorption rate (mg Li ·h -1 )]]> Example 1 30 2.52·10 -4 ]] Example 5 15 2.14·10 -4 ]]> Example 6 45 2.31 · 10 -4 ]] Example 7 60 1.63·10 -4 ]]>

[0081] Examples 8-11

[0082] On the basis of Example 1, the feed liquid was changed to a mixed solution containing 250 mg·L -1 Li + and different concentrations of sodium chloride (0.0wt%, 5.0wt%, 10.0wt% and 15.0wt% respectively). Under the irradiation of sunlight, the adsorption experiment was carried out using the adsorption device, and the experiment lasted for 10h.

[0083] The Li + adsorption capacity of the adsorption device in Examples 8-11 under solar irradiation was tested, and the results are shown in the table below. The photos of the adsorption device in Example 11 before and after the experiment are shown in Figure 5 .

[0084] Table 4. Li + adsorption capacity of the adsorption devices in Examples 8-11 under solar irradiation

[0085] NaCI concentration (wt%) Li + Adsorption capacity (mg Li )]]> Example 8 0.0 2.47 Example 9 5.0 2.49 Example 10 10.0 2.43 Example 11 15.0 2.45

[0086] From Figure 5As can be seen from the data in Table 4, even if the concentration of NaCl in the feed solution is increased to 15 wt%, the photo-thermal enhanced lithium ion adsorption device does not have NaCl salt scale, and still exhibits stable Li+ adsorption performance.

[0087] The above-described embodiments illustrate the technical solutions and beneficial effects of the present application in detail. It should be understood that the above-described embodiments are only specific embodiments of the present application and are not used to limit the present application. Any modification, supplement, and equivalent replacement within the principle range of the present application should be included in the protection range of the present application.

Claims

1. A photo-thermal enhanced lithium ion adsorption device for lithium extraction from seawater, characterized in that, The application relates to a light-heat enhanced lithium ion adsorber, which comprises a material liquid tank, a through hole is arranged on the side wall of the material liquid tank, the through hole is communicated with one end of the light-heat enhanced lithium ion adsorber, and the other end of the light-heat enhanced lithium ion adsorber is inclined to the bottom of the material liquid tank; the included angle between the length direction of the light-heat enhanced lithium ion adsorber and the material liquid tank is 10-80 degrees. The light-heat enhanced lithium ion adsorber comprises a columnar core material and a shell layer wrapped outside the side wall of the core material; the core material is a hydrophilic lithium ion adsorption nanofiber material, the average fiber diameter of the hydrophilic lithium ion adsorption nanofiber is 100-1200 nm; the shell layer is a hydrophobic light-heat nanofiber material, the average fiber diameter of the hydrophobic light-heat nanofiber is 100-5000 nm; the core material is formed by winding a hydrophilic lithium ion adsorption nanofiber film into a columnar shape, and the cross section diameter of the core material is 0.2-4.6 cm; the thickness of the shell layer is 50-2000 microns. The preparation method of the light-heat enhanced lithium ion adsorber comprises the following steps: (1) dissolving and uniformly mixing a hydrophilic polymer and a lithium ion sieve to obtain spinning liquid A; dissolving and uniformly mixing a hydrophobic polymer and a light-heat conversion material to obtain spinning liquid B; (2) electrospinning the spinning liquid A on a flat collector to obtain a hydrophilic lithium ion adsorption nanofiber pad, and cutting and winding the nanofiber pad into a columnar shape; loading the hydrophobic light-heat nanofiber formed by electrospinning the spinning liquid B onto the side wall of the continuously rotating hydrophilic fiber column to construct the light-heat enhanced lithium ion adsorber.

2. The photo-thermal enhanced lithium ion adsorption device for lithium extraction from seawater according to claim 1, wherein, The thickness of the shell layer is 100-600 microns.

3. The photo-thermal enhanced lithium ion adsorption device for lithium extraction from seawater according to claim 1, wherein, The hydrophilic lithium ion adsorption nanofiber is a hydrophilic polymer fiber coated with lithium ion sieve; the hydrophilic polymer is at least one of polyacrylonitrile, polyethersulfone, polyvinyl alcohol and cellulose acetate; the lithium ion sieve is at least one of H 1.33 Mn 1.67 O4, H 1.6 Mn 1.6 O4, H2TiO3, H4Ti5O 12 and λ-MnO2.

4. The photo-thermal enhanced lithium ion adsorption device for lithium extraction from seawater according to claim 1, wherein, The hydrophobic light-heat nanofiber is a hydrophobic polymer fiber coated with a light-heat conversion material; the hydrophobic polymer is at least one of polyurethane, polyvinylidene fluoride, polymethyl methacrylate, polylactic acid and polystyrene; and the light-heat conversion material is at least one of graphene, carbon nanotube, carbon black, graphite and ferroferric oxide.

5. A method for extracting lithium from seawater based on the photo-thermal enhanced lithium ion adsorption device according to any one of claims 1-4, characterized in that, The application further relates to a light-heat enhanced lithium ion adsorption device, which comprises the light-heat enhanced lithium ion adsorber and a material liquid tank. The seawater is injected into the material liquid tank, and the lithium ions in the seawater are adsorbed by the light-heat enhanced lithium ion adsorber under the irradiation of sunlight; After adsorption saturation, hydrochloric acid solution is used to desorb the lithium ions from the light-heat enhanced lithium ion adsorber, the light-heat enhanced lithium ion adsorption device is cleaned after desorption, and the circulation regeneration of the light-heat enhanced lithium ion adsorption device is completed.

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