CN110867559A - A Porous Lithium Metal Anode, Preparation and Application in Lithium Metal Batteries - Google Patents

Abstract

The invention belongs to the technical field of lithium metal batteries, and particularly discloses a porous lithium metal anode which comprises a porous metal current collector, a metal lithium layer compounded on a framework of the porous metal current collector, and a lithium oxide layer covering the surface of the metal lithium layer. The invention also discloses a preparation method of the porous lithium metal anode, which comprises the steps of carrying out surface oxidation on the porous metal current collector, then filling metal lithium into the porous metal current collector after the surface oxidation, and carrying out a replacement reaction to obtain the porous lithium metal anode. The invention also discloses application of the porous lithium metal anode and a prepared lithium metal battery. In the invention, the existence of the lithium oxide layer formed in situ reduces the direct contact of the lithium metal and the electrolyte, effectively avoids the occurrence of interface reaction, and simultaneously maintains the advantage of high specific surface area of the porous metal current collector. Meanwhile, the good lithium affinity of the oxide layer is beneficial to stabilizing the transmission of lithium ions, and finally the long cycle life of the lithium metal battery is realized.

Description

A Porous Lithium Metal Anode, Preparation and Application in Lithium Metal Batteries

technical field

The invention belongs to the field of energy storage, and in particular relates to the preparation and application of a porous lithium metal anode.

Background technique

The mechanism of action of metallic lithium anode in batteries is the deposition and dissolution of metallic lithium, and its basic reaction formula is:

Charge: Li ⁺ +e=Li; discharge: Li-e=Li ⁺ . Different from the negative electrode of the conventional lithium ion battery, the intercalation and extraction of lithium ions in the graphite negative electrode occurs.

With its ultra-high theoretical specific capacity (3860mAh/g) and the lowest electrode potential (-3.04 V), metal lithium is regarded by more and more researchers as the most promising anode material for next-generation lithium batteries. In this context, lithium-sulfur batteries and lithium-air batteries using lithium metal as anodes have made great strides in recent years. However, the huge volume effect during cycling of Li dendrites and Li metal batteries limits their practical applications. To deal with these problems, a large number of strategies, such as optimizing lithium salts in electrolytes, solvents, functional additives and even ionic liquids, have been extensively developed and studied. For example, Miao Wang et al. [P.Zhang, J.Zhu, M.Wang, N.Imanishi, O.Yamamoto, Lithium dendritesuppression and cycling efficiency of lithium anode, Electrochemistry Communications 87(2018) 27-30.] adopt 2.5M lithium salt to change the physicochemical properties of the electrolyte, thereby inhibiting the growth of lithium dendrites. While Ji-Guang Zhang et al. [J.Qian, W.Xu, P.Bhattacharya, M.Engelhard, W.A.Henderson, Y.Zhang, J.-G. Zhang, Dendrite-free Li deposition using trace-amounts of water as an electrolyte additive, Nano Energy 15 (2015) 135-144.] By adding a trace amount of water to the electrolyte, a lithium fluoride-rich SEI film is formed on the surface of the lithium sheet, thereby inhibiting the growth of dendrites. Behind these studies, researchers have achieved very gratifying results, and a large number of lithium dendrites have been successfully suppressed. However, the huge volume effect during cycling of lithium metal batteries, especially at high areal capacities, remains to be resolved.

In recent years, researchers have found that loading metallic lithium in 3D porous current collectors can effectively alleviate the volume change during the deposition/dissolution of metallic lithium. At the same time, the ultra-high specific surface area of the 3D porous current collectors can fully reduce the current density on the electrode surface, enabling dendrite-free Li deposition of metallic lithium at lower current densities, such as Quan-Hong Yang et al. [Q.Yun, Y. -B.He, W.Lv, Y.Zhao, B.Li, F.Kang, Q.-H.Yang, Chemical dealloying derived3D porous current collector for Li metal anodes, Advanced Materials 28(32)(2016)6932- 6939.] A porous copper current collector was prepared by dealloying a Cu-Zn alloy. As a working electrode, the porous copper current collector achieved 150 cycles at a current density of 1 mA/cm ² . Similarly, Yu-Guo Guo et al. [S.-H.Wang, Y.-X.Yin, T.-T.Zuo, W.Dong, J.-Y.Li, J.-L.Shi, C. .-H. Zhang, N.-W.Li, C.-J.Li, Y.-G.Guo, Stable Li metal anodes via regulating lithium plating/stripping invertically aligned microchannels, Advanced Materials 29(40) (2017) 1703729-1703736.] Porous copper was prepared by laser technology, and a stable cycle of 200 cycles was achieved at a current density of 1 mA/ ^cm2 . However, as a double-edged sword, the 3D porous current collector's ultra-high specific surface area not only reduces the current density on the electrode surface, but also greatly increases the contact area between metal lithium and the electrolyte. A large amount of contact area leads to a large number of interfacial side reactions, resulting in a large loss of active lithium. Therefore, the current traditional lithium-supported 3D porous current collectors are difficult to be truly applied in industry as anode materials for lithium metal batteries.

SUMMARY OF THE INVENTION

In view of the common problems of 3D lithium metal anodes, the first object of the present invention is to provide a porous lithium metal anode coated with a lithium oxide layer in situ.

The second object of the present invention is to provide a method for preparing the porous lithium metal anode, which aims to deposit lithium in-situ on the skeleton of the 3D current collector and cover the lithium oxide layer in-situ to significantly improve the electrical performance of the anode.

The third object of the present invention is to provide an application of the porous lithium metal anode.

A porous lithium metal anode comprises a porous metal current collector, a metal lithium layer compounded on the framework of the porous metal current collector, and a lithium oxide layer covering the surface of the metal lithium layer.

In the lithium metal anode of the present invention, a metal lithium layer is innovatively deposited on the skeleton of the pores of the 3D porous metal current collector, and a lithium oxide layer is coated on the surface of the metal lithium layer; , which can significantly reduce the apparent current density of the lithium metal surface, achieve stable cycling of metal lithium at high current density, and effectively improve the cycling performance at high current density (2-5 mA/cm ² ). At the same time, the existence of a uniform and dense lithium oxide layer effectively avoids the direct contact between the electrolyte and metal lithium, and inhibits the occurrence of the conventional 3D lithium metal anode interfacial reaction and the continuous loss of metal lithium.

Preferably, the material of the 3D porous metal current collector is at least one of titanium, chromium, manganese, iron, cobalt, nickel, and copper.

Preferably, the porous metal current collector is porous titanium, porous chromium, porous manganese, porous iron, porous cobalt, porous nickel, porous copper and other porous metal current collectors and their binary and ternary porous alloy current collectors. any of the .

Preferably, the 3D porous binary alloy current collector is porous nickel copper, porous nickel titanium, porous nickel chromium, porous nickel iron, porous nickel cobalt, porous nickel manganese, porous iron titanium, porous iron chromium, porous iron copper, Any one of porous iron-cobalt, porous iron-manganese, porous cobalt-titanium, porous cobalt-copper, and porous cobalt-manganese alloy. The composition ratio of the 3D porous binary alloy is arbitrary.

Preferably, the 3D porous ternary alloy current collector is porous nickel-copper-titanium, porous nickel-copper-iron, porous nickel-copper-cobalt, porous nickel-copper-manganese, porous iron-cobalt-nickel, porous iron-chromium-nickel, porous nickel-copper-chromium alloy any of the . The composition ratio of the 3D porous ternary alloy is arbitrary.

Further preferably, the material of the 3D porous metal current collector is porous nickel, porous copper, porous nickel-chromium, porous nickel-iron, porous nickel-copper, porous iron-copper, porous cobalt-copper, porous nickel-copper-titanium, porous nickel-copper-iron, Porous nickel copper cobalt, porous nickel copper manganese. Preferred metal current collectors perform better.

Most preferably, the material of the 3D porous metal current collector is porous nickel (also called nickel foam).

The thickness of the 3D porous current collector is 10-1200 μm; preferably 30-500 μm; more preferably 40-70 μm.

The porosity of the 3D porous current collector is 20-99%; preferably 30-90%; more preferably 40-90%. The inventors have found that the use of a current collector with higher porosity helps to improve the electrical performance of the prepared anode, especially the cycle performance under high current density.

The porosity of the 3D porous current collector is most preferably 40 to 60%.

The pore spacing of the 3D porous current collector is 1-400 μm; preferably 5-300 μm; more preferably 40-120 μm. The larger pore size helps to further improve the electrical performance of the prepared anode.

Preferably, in the porous lithium metal anode, the content of metallic lithium ranges from 10 to 90 wt.%.

Preferably, the thickness of lithium oxide is in the range of 10 to 700 nm.

Preferably, the content of metallic lithium is 2-12 mAh/cm 2 ; more preferably, it is 5-8 mAh/cm 2 .

The metal lithium layer and the lithium oxide layer described in the present invention are formed in situ by the metal oxide material and metal lithium compounded on the surface of the 3D porous current collector through a replacement reaction. The metal element of the metal oxide material is the same as that of the 3D porous current collector.

Preferably, the metal oxide material is obtained by the oxidative roasting of the 3D porous current collector.

The atmosphere of the oxidative roasting is, for example, an oxygen-containing atmosphere, wherein the oxygen volume content is 5-90%; preferably 15-70%; more preferably 25-55%.

The temperature of the oxidative roasting is 500 to 800°C.

The present invention also provides a method for preparing the porous lithium metal anode. The porous metal current collector is subjected to surface oxidation (oxidative pretreatment), and then metal lithium is filled into the surface-oxidized porous metal current collector to perform a replacement reaction, The metal lithium layer and the lithium oxide layer covering the surface of the metal lithium layer are formed in situ on the surface of the framework to prepare the porous lithium metal anode.

The invention innovatively pre-oxidizes the porous metal current collector in advance, so that the surface of the skeleton is slightly oxidized, and then the in-situ formed oxidation product is used as a material for inducing lithium deposition, so that lithium preferentially enters the skeleton and undergoes a replacement reaction. , to achieve the purpose of inducing the in-situ deposition of lithium in the framework, and in addition, the dense lithium oxide generated by the replacement reaction in-situ covers the surface of lithium, forming native SEI protection. The preparation method of the present invention realizes the induced in-situ deposition of lithium and the in-situ one-step formation of the SEI protective film, so that the uniformity of the lithium deposition and the lithium oxide layer can be fully guaranteed, and the effective specific surface area of the 3D metal current collector can be fully utilized. Solve the problem of lithium dendrites and significantly improve the cycle life of the anode, especially the cycle performance at high current densities.

Preferably, the surface oxidation is: calcining the porous metal current collector in an oxygen-containing atmosphere. The study found that this processing method is not only convenient for processing, but also facilitates the one-step in-situ deposition of the subsequent metal lithium layer and lithium oxide layer.

The inventors found that, for the innovative porous metal lithium anode of the present invention, controlling the degree of oxidation of the surface of the 3D metal current collector skeleton has a great influence on the performance of the subsequent anode; As well as time and other parameters, the in-situ deposition effect of the metal lithium layer and the lithium oxide layer can be further improved, and the electrical performance of the prepared porous metal lithium anode can be further improved.

The oxygen volume content of the oxygen-containing atmosphere is 5 to 90%.

Preferably, the oxygen volume content of the oxygen-containing atmosphere is 15 to 70%.

More preferably, the oxygen volume content of the oxygen-containing atmosphere is 25 to 55%. Under this preferred atmosphere, the electrical properties of the subsequently produced anodes can be unexpectedly improved.

The oxygen-containing atmosphere includes oxygen and protective gas. The protective gas is, for example, nitrogen or an inert gas.

Preferably, the oxygen-containing atmosphere is a mixed atmosphere of oxygen and nitrogen.

The calcination temperature is 100 to 1000°C; preferably 500 to 800°C; more preferably 500 to 700°C.

The inventors of the present invention have found that, for the lithium metal anode of the present invention, controlling the oxidative roasting temperature at 500-800°C, especially 500-700°C, can unexpectedly improve the electrical performance of the prepared lithium metal anode, especially the high Cycling performance at current density.

Preferably, the oxidative roasting time is 0.2-10 h.

Preferably, the oxidative roasting time is 0.5-5h. Under the stated atmosphere and calcination temperature, the preferred calcination time yields better calcination results.

Preferably, the method of filling metallic lithium is electrodeposition or melting; preferably electrodeposition. It is found that the lithium filling is performed by the electrodeposition method, and the in-situ formation of the metal lithium layer and the lithium oxide layer is utilized.

Preferably, the electrodeposition step is as follows: using the oxidized porous metal current collector as a working electrode and a lithium sheet as a counter electrode, electrodepositing in an organic solvent containing a lithium salt.

Preferably, the amount of electrodeposited metal lithium is 2-12 mAh/cm 2 ; more preferably, it is 5-8 mAh/cm 2 . Under the preferred amount of deposited lithium, the obtained anode material has excellent electrical properties, especially cycle properties.

The present invention also provides an application of the porous lithium metal anode as an anode of a lithium metal battery.

The present invention also provides a lithium metal battery using the porous lithium metal anode of the present invention as an electrode.

Preferably, the lithium metal battery is a lithium sulfur battery, a lithium iodine battery, a lithium selenium battery, a lithium tellurium battery, a lithium oxygen battery or a lithium carbon dioxide battery.

Beneficial effects:

In the proposed porous lithium metal anode, the high specific surface area of the porous lithium metal anode can significantly reduce the apparent current density of the lithium metal surface and achieve stable cycling of metal lithium at high current density. At the same time, the existence of a uniform and dense lithium oxide layer effectively avoids the direct contact between the electrolyte and metallic lithium, and suppresses the occurrence of conventional 3D lithium anode interfacial reactions and the continuous loss of metallic lithium. Moreover, the actual specific capacity of the 3D lithium anode prepared by this method can be as high as ~3500mAh/g, which is 3-10 times that of the conventional lithium-ion battery negative electrode material. In addition, the facile preparation process is beneficial to promote the practical application of 3D metal lithium industrialization.

Description of drawings

FIG. 1 is a SEM image of the copper foam in Example 1. FIG.

FIG. 2 is an SEM image of the oxidized copper foam in Example 1. FIG.

FIG. 3 is the EDS of the oxidized copper foam in Example 1. FIG.

4 is a graph showing the cycle performance of the copper foam in Example 1 and the oxidized copper foam.

Detailed ways

The following are specific descriptions of preferred embodiments of the present invention, which do not constitute any limitation to the present invention, that is, the present invention is not meant to be limited to the above-mentioned embodiments, and common modifications or alternative compounds in the technical field are included in the right of the application within the limits of the requirements.

Example 1

The commercialized copper foam current collector (Fig. 1) has a thickness of 40 μm, a porosity of 60%, and a pore spacing of 80 μm. The copper foam was placed in an oxygen-containing nitrogen atmosphere (oxygen content of 20%) and sintered at 500°C In 1 h, copper oxide modified copper foam was obtained (Fig. 2). The electrode was used as the working electrode, the metal lithium sheet was used as the counter electrode, and 1M LiTFSI/DOL:DME (volume ratio = 1:1) containing 1 wt.% LiNO ₃ was used as the electrolyte to assemble a button battery, and the charge-discharge cycle test was carried out. . At the same time, the corresponding charge-discharge cycle test was carried out with pure copper foam as the control sample.

The test found that the surface of the copper foam was uniformly covered with a layer of dense copper oxide (Figure 3), which achieved uniform dendrite-free lithium deposition and effectively avoided the occurrence of lithium dendrites and interfacial reactions. Especially at a current density of 2 mA/cm ² , the cycle life of the oxidized copper foam electrode was more than 6 times that of the pure copper foam electrode (Fig. 4).

Example 2

The thickness of the commercial porous nickel-iron current collector is 70 μm, the porosity is 40%, and the pore spacing is 120 μm. The porous nickel-iron current collector was placed in an oxygen-containing argon atmosphere (oxygen content of 30%), and sintered at 700 ° C for 2 h The porous nickel iron modified by the oxide layer is obtained. The electrode was used as the working electrode, the metal lithium sheet was used as the counter electrode, and 1M LiTFSI/DOL:DME (volume ratio = 1:1) containing 1 wt.% LiNO ₃ was used as the electrolyte to assemble a button battery, and the charge-discharge cycle test was carried out. . At the same time, the corresponding charge-discharge cycle tests were carried out with pure porous nickel-iron as the control sample.

The test found that the porous nickel-iron surface was uniformly covered with a dense oxide layer. Especially at a current density of 5 mA/cm ² , the cycle life of the oxidized porous NiFe electrode is more than 5 times that of the pure porous NiFe electrode.

Example 3

Full battery case:

The copper oxide-modified foam copper prepared in Example 1 was used as the working electrode, and then at a current density of 0.5 mA/cm ² , 5 mAh/cm ² of metallic lithium was deposited on the electrode to prepare a composite anode material, and then mixed with S-rich A lithium-sulfur battery composed of a simple carbon nanotube positive electrode was subjected to a charge-discharge cycle test at 1C in a 1M LiTFSI/DOL:DME (volume ratio=1:1) electrolyte containing 1wt.% LiNO ₃ .

Comparative Example 1

Using foamed copper as the working electrode, and then at a current density of 0.5mA/ ^cm2 , 5mAh/ ^cm2 of metallic lithium was deposited into the foamed copper, and then combined with the S-rich carbon nanotube positive electrode to form a lithium-sulfur battery at 1M LiTFSI/ The charge-discharge cycle test was carried out in an electrolyte solution containing 1 wt.% LiNO ₃ in DOL:DME (volume ratio=1:1).

The test results of the prepared battery are shown in Table 1.

Table 1

Comparing Example 3 with Comparative Example 1, it is found that the coulombic efficiency and cycle performance of the porous lithium metal anode of the present invention are significantly improved.

Example 4

The thickness of commercial nickel foam and foam iron current collectors are both 50 μm, the porosity is 50%, and the pore spacing is 90 μm. The nickel foam and iron foam are placed in an oxygen-containing nitrogen atmosphere (oxygen content 30%) , sintered at 600 °C for 1.5 h to obtain nickel oxide modified nickel foam and iron oxide modified iron foam, respectively. The two types of electrodes were used as the working electrodes respectively, the metal lithium sheet was used as the counter electrode, and 1M LiTFSI/DOL:DME (volume ratio = 1:1) containing 1 wt.% LiNO ₃ was used as the electrolyte for button cell assembly. The charge-discharge cycle test was performed at a current density of /cm ² .

The test results of the prepared battery are shown in Table 2.

Example 5

The thickness of the two commercial nickel foam current collectors is 50 μm, the pore spacing is 90 μm, and the porosity is 30% and 90%, respectively. ), sintered at 600 °C for 1.5 h to obtain nickel oxide modified nickel foam. The two electrodes were used as the working electrode, the metal lithium sheet was used as the counter electrode, and 1MLiTFSI/DOL:DME (volume ratio = 1:1) containing 1wt.% _LiNO3 was used as the electrolyte for button cell assembly. The charge-discharge cycle test was carried out at a current density of ² .

The test results of the prepared battery are shown in Table 2.

Example 6

The thickness of the commercial nickel foam current collector is 50 μm, the porosity is 50%, and the pore spacing is 5 μm and 300 μm, respectively. Sintered at ℃ for 1.5 h to obtain nickel oxide modified nickel foam. Two kinds of electrodes were used as the working electrode, the metal lithium sheet was used as the counter electrode, and 1M LiTFSI/DOL:DME (volume ratio = 1:1) containing 1wt.% _LiNO3 was used as the electrolyte for button cell assembly. The charge-discharge cycle test was carried out at a current density of ² .

The test results of the prepared battery are shown in Table 2.

Table 2

Example 4 shows that the current collector material has a certain influence on the electrical properties. It is found in Example 4 that when the foamed nickel is used as the porous metal current collector, the electrical properties can be further improved unexpectedly.

Example 5 shows that the large porosity helps to improve the performance, especially when the porosity is 40-60%, the electrical performance of the obtained anode, especially the cycle performance, is excellent.

Example 6 shows that within the preferred range, a large pore spacing helps to improve performance, and the anode obtained at the preferred 40-300 μm has excellent electrical performance, especially cycle performance.

Example 7

The commercialized porous iron-copper current collector has a thickness of 60 μm, a porosity of 60%, and a pore spacing of 45 μm. After sintering for 2 h, two kinds of iron oxide-copper oxide co-modified porous iron-copper were obtained. The two electrodes obtained were used as working electrodes, metal lithium sheets were used as counter electrodes, and 1M LiTFSI/DOL:DME (volume ratio = 1:1) containing 1wt.% LiNO3 was used as electrolyte for button cell assembly. The charge-discharge cycle test was carried out at a current density of cm ² .

The test results of the prepared battery are shown in Table 3.

Example 8

The thickness of the commercialized porous iron-copper current collector is 60 μm, the porosity is 60%, and the pore spacing is 45 μm. Two kinds of iron oxide-copper oxide co-modified porous iron-copper were obtained by sintering at 700 °C for 2 h in a 90% nitrogen atmosphere. The obtained electrodes were used as working electrodes, metal lithium sheets were used as counter electrodes, and 1M LiTFSI/DOL:DME (volume ratio = 1:1) containing 1wt.% LiNO3 was used as electrolyte for button cell assembly. The charge-discharge cycle test was carried out at a current density of ² .

The test results of the prepared battery are shown in Table 3.

Example 9

The commercialized porous iron-copper current collector has a thickness of 60 μm, a porosity of 60%, and a pore spacing of 45 μm. The porous iron-copper was placed in a nitrogen atmosphere with an oxygen content of 40%, and sintered at 700 °C for 0.2 and 0.5 μm, respectively. , 3, 5, 10h to obtain two kinds of iron oxide-copper oxide co-modified porous iron-copper. The obtained electrodes were used as working electrodes, metal lithium sheets were used as counter electrodes, and 1M LiTFSI/DOL:DME (volume ratio = 1:1) containing 1wt.% LiNO3 was used as electrolyte for button cell assembly. The charge-discharge cycle test was carried out at a current density of ² .

The test results of the prepared battery are shown in Table 3.

table 3

Example 7 shows that the performance of the current collector obtained in a nitrogen atmosphere is better. Examples 8 and 9 show that when the oxygen content is 25-55%, the performance of the obtained material is better. The electrical properties of the prepared anode are better.

Example 10

The commercialized porous NiCuFe current collector has a thickness of 150 μm, a porosity of 75%, and a pore spacing of 100 μm. The porous NiCuFe collector was placed in a nitrogen atmosphere with an oxygen content of 35%, and sintered at 650 °C, respectively. Oxide-modified porous nickel-copper-iron was obtained in 3.5h. The obtained electrode was used as the working electrode, the metal lithium sheet was used as the counter electrode, and 1M LiTFSI/DOL:DME (volume ratio = 1:1) containing 1 wt.% LiNO3 was used as the electrolyte for button cell assembly. At the current density of ² , 0.5, 2, 5, 8, and 12 mAh/cm2 of metallic lithium was deposited on the working electrode to obtain a composite 3D lithium anode, which was combined with the S-rich graphene cathode to form a lithium-sulfur battery. At 1C, Perform a charge-discharge cycle test.

The test results of the prepared battery are shown in Table 4.

Table 4

The results show that the performance of the 3D lithium anode with the deposited lithium content within 5～8mAh/cm2 is better.

Example 11

The copper oxide-modified foam copper prepared in Example 1 was used as an electrode, and contacted with metallic lithium melted in an argon atmosphere at 220° C. to obtain a composite lithium anode material, and then combined with the S-rich carbon nanotube positive electrode to form lithium Sulfur battery, in 1M LiTFSI/DOL:DME (volume ratio=1:1) electrolyte containing 1wt.% LiNO3, at 1C, the charge-discharge cycle test was carried out.

The test results of the prepared battery are shown in Table 1.

It can be seen from Table 1 that the effect of filling lithium by melting is slightly worse than that of filling lithium by electrodeposition.

Comparative Example 2

This comparative example discusses the use of planar current collectors, as follows:

The commercial copper foil was placed in an oxygen-containing nitrogen atmosphere (oxygen content of 20%), and sintered at 500° C. for 1 h to obtain a copper oxide-modified copper foil. The electrode was used as the working electrode, the metal lithium sheet was used as the counter electrode, and 1M LiTFSI/DOL:DME (volume ratio = ¹ :1) containing 1wt.% _LiNO3 was used as the electrolyte for button cell assembly. Under the current density, the charge-discharge cycle test was carried out. At the same time, the corresponding charge-discharge cycle test was carried out with copper foil as the control sample.

The test results of the prepared battery are shown in Table 5.

Comparative Example 3

The thickness of the commercial foamed copper current collector is 40 μm, the porosity is 10%, and the pore spacing is 80 μm. The copper foam is placed in an oxygen-containing nitrogen atmosphere (oxygen content 20%), and sintered at 500 ° C for 1 h to obtain copper oxide Finished copper foam. The electrode was used as the working electrode, the metal lithium sheet was used as the counter electrode, and 1M LiTFSI/DOL:DME (volume ratio = ¹ :1) containing 1wt.% _LiNO3 was used as the electrolyte for button cell assembly. Under the current density, the charge-discharge cycle test was carried out.

The test results of the prepared battery are shown in Table 5.

Comparative Example 4

The thickness of the commercial foamed copper current collector is 40 μm, the porosity is 60%, and the pore spacing is 500 μm. The copper foam is placed in an oxygen-containing nitrogen atmosphere (oxygen content 20%), and sintered at 500 ° C for 1 h to obtain copper oxide Finished copper foam. The electrode was used as the working electrode, the metal lithium sheet was used as the counter electrode, and 1M LiTFSI/DOL:DME (volume ratio = ¹ :1) containing 1wt.% _LiNO3 was used as the electrolyte for button cell assembly. Under the current density, the charge-discharge cycle test was carried out.

The test results of the prepared battery are shown in Table 5.

Comparative Example 5

This comparative example discusses the roasting temperature as follows:

A commercialized copper foam current collector with a thickness of 40 μm, a porosity of 60%, and a pore spacing of 80 μm was placed in an oxygen-containing nitrogen atmosphere (oxygen content of 20%) and sintered at 50 and 1200 °C, respectively. In 1 h, two kinds of copper oxide modified copper foams were obtained. The two electrodes were used as the working electrodes, the metal lithium sheet was used as the counter electrode, and 1M LiTFSI/DOL:DME (volume ratio = 1:1) containing 1 wt.% LiNO ₃ was used as the electrolyte for button cell assembly. Under the current density of / ^cm2 , the charge-discharge cycle test was carried out.

The test results of the prepared battery are shown in Table 5.

Comparative Example 6

This comparative example explores oxygen levels as follows:

The thickness of the commercial foamed copper current collector is 40 μm, the porosity is 60%, and the pore spacing is 80 μm. In an argon atmosphere, and sintered at 500 °C for 1 h, three kinds of copper oxide modified copper foams were obtained. The three electrodes were used as the working electrodes, the metal lithium sheet was used as the counter electrode, and 1M LiTFSI/DOL:DME (volume ratio = 1:1) containing 1wt.% _LiNO3 was used as the electrolyte for button cell assembly. Under the current density of /cm ² , the charge-discharge cycle test was carried out.

The test results of the prepared battery are shown in Table 5.

table 5

Comparative Examples 2 to 6 show that with planar current collectors or not within the preferred range conditions, poorer performance will be obtained.

Claims (10)

1. A porous lithium metal anode characterized by: the lithium ion battery comprises a porous metal current collector, a metal lithium layer compounded on a porous metal current collector framework and a lithium oxide layer covering the surface of the metal lithium layer.

2. The porous lithium metal anode of claim 1, wherein: the material of the 3D porous metal current collector is at least one of titanium, chromium, manganese, iron, cobalt, nickel and copper;

preferably, the thickness of the 3D porous current collector is 10-1200 μm; more preferably 30 to 500 μm;

preferably, the porosity of the 3D porous current collector is 20-99%; further preferably 30-90%;

preferably, the pore space of the 3D porous current collector is 1-400 μm; more preferably 5 to 300 μm.

3. The porous lithium metal anode of claim 1, wherein: the content of the metal lithium ranges from 10 to 90 wt.%; the thickness of the lithium oxide ranges from 10 nm to 700 nm.

4. The porous lithium metal anode of any one of claims 1 to 3, wherein: the metal lithium layer and the lithium oxide layer are formed in situ by the replacement reaction of a metal oxide material and metal lithium compounded on the surface of the 3D porous current collector;

preferably, the metal element of the metal oxide material is the same as the metal element of the 3D porous current collector;

preferably, the metal oxide material is obtained by oxidizing and roasting the 3D porous current collector.

5. A method for preparing a porous lithium metal anode according to any one of claims 1 to 4, characterized in that: carrying out surface oxidation on the porous metal current collector, then filling metal lithium into the porous metal current collector after the surface oxidation, and carrying out a displacement reaction to obtain the porous lithium metal anode;

preferably, the surface oxidation is: and roasting the porous metal current collector in an oxygen-containing atmosphere.

6. The method of preparing a porous lithium metal anode of claim 5, wherein: the oxygen volume content of the oxygen-containing atmosphere is 5-90%; preferably 15 to 70%.

7. The method of preparing a porous lithium metal anode of claim 5, wherein: the roasting temperature is 100-1000 ℃; preferably 500-800 ℃; further preferably 500-700 ℃;

preferably, the roasting time is 0.2-10 h; further preferably 0.5 to 5 hours.

8. The method of preparing a porous lithium metal anode according to any one of claims 5 to 7, wherein: the method for filling the metallic lithium is electrodeposition or melting;

preferably, the electrodeposition step is: taking the oxidized porous metal current collector as a working electrode and a lithium sheet as a counter electrode, and carrying out electrodeposition in an organic solvent containing lithium salt;

the amount of the electrodeposited metal lithium is 2-12 mAh/cm 2; further preferably 5 to 8mAh/cm 2.

9. Use of a porous lithium metal anode according to any one of claims 1 to 4 or a porous lithium metal anode prepared by the preparation method according to any one of claims 5 to 8, wherein: the anode is used as the anode of the lithium metal battery;

preferably, the lithium metal battery is a lithium sulfur battery, a lithium iodine battery, a lithium selenium battery, a lithium tellurium battery, a lithium oxygen battery or a lithium carbon dioxide battery.

10. A lithium metal battery using the porous lithium metal anode according to any one of claims 1 to 4 or the porous lithium metal anode prepared by the preparation method according to any one of claims 5 to 8 as an electrode.

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