A fast-charging negative electrode and its application in anode-free batteries

Abstract

The present invention provides a fast-charging negative electrode with high lithium / sodium affinity and high conductivity, the conductivity of which is not less than 10mS / m; its composition is Cu x M y A z , wherein M is three or more of the elements Zn, Ni, Mn, Sn, Pb, Mg, Al, Ga, Ge, Co, Fe, V, Cr, and Ti; and A is one or more of the elements B, Si, P, and Se. The fast-charging negative electrode provided by the present invention can improve the affinity between the negative electrode and lithium / sodium, allowing lithium / sodium to be uniformly deposited at high current density, inhibiting the formation of dendrites, even at 100 mA / cm 2 It still has a good dendrite inhibition effect under ultra-high current density, which can greatly improve the fast charging capacity retention rate of anode-free batteries. The preparation method involved is relatively simple and the overall preparation cost is low, which is suitable for promotion and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a fast-charging negative electrode and its application in an anode-free battery. Background Art

[0002] In order to improve the energy density of batteries, researchers have developed a new type of anode-free battery in recent years. By not using negative electrode active materials, the battery energy density has been greatly improved. The principle of this technology is to deposit the lithium in the positive electrode material on the negative electrode current collector through formation charging. However, anode-free batteries have problems such as poor fast charging performance. The main reason is that the commonly used negative electrode current collector is copper foil, but due to the poor affinity between copper foil and lithium, lithium is difficult to deposit evenly on the surface of the copper foil during the charging process. During the operation of the battery, a large number of lithium dendrites and dead lithium will be formed, causing the internal resistance of the battery to increase, affecting the fast charging performance of the battery. Especially in the case of high-rate charging, dendrites will grow rapidly, break to form dead lithium, causing the battery capacity to decay significantly, resulting in poor fast charging performance of the battery.

[0003] Technologies that can improve the lithium deposition effect include using a three-dimensional current collector, modifying the current collector surface to form a lithium-affinity layer, and using an alloy current collector with good lithium affinity.

[0004] Chinese patent CN202110119058.8 discloses a method for regulating the thermal oxidation of the surface of a lithium metal negative electrode current collector to improve the cycle life. The metal current collector is first subjected to degreasing and pickling treatments in sequence, and then a three-dimensional structure is formed on the surface of the metal current collector. The three-dimensional current collector surface is then subjected to thermal oxidation treatment to achieve a change in the lithium affinity of the negative electrode current collector surface to improve the deposition uniformity of lithium metal on the current collector surface. At 1mA / cm 2 At high charge and discharge rates, the growth of lithium dendrites can be effectively suppressed, thereby improving the battery's cycle life. However, due to the poor conductivity of the oxide layer, charging at high current densities can significantly increase the polarization of the negative electrode, deteriorate the uniformity of lithium deposition, and make it difficult to suppress the growth of lithium dendrites.

[0005] Chinese patent CN201810219640.X discloses a copper-zinc alloy current collector that inhibits lithium dendrites. A conventional current collector is coated with a layer of copper-zinc alloy with a thickness of 10nm to 1μm. The atomic content of zinc in the copper-zinc alloy is 1% to 5%. Compared with conventional current collectors, the copper-zinc alloy current collector provides more active sites for metallic lithium deposition. Deposition / dissolution experiments were conducted using a blue electrode with a current density of 0.5mA / cm 2 , the copper-zinc alloy negative electrode still maintains a small voltage hysteresis after 1000 hours of cycling. However, due to the limited lithium affinity of zinc, it cannot improve the lithium deposition effect of high current density charging.

[0006] Chinese patent CN202210764790.5 discloses a high-entropy alloy current collector, which replaces the existing copper foil current collector. While meeting the relevant requirements of anode-free lithium metal batteries, the high-entropy alloy current collector can effectively regulate the deposition of lithium, reduce or avoid the formation of lithium dendrites, and overcome the shortcomings of existing anode-free lithium metals. At charge and discharge rates of 0.1C and 1C, the coulombic efficiency, initial discharge capacity, and capacity retention rate of anode-free lithium metal batteries can be improved. However, since the high-entropy alloy contains a large amount of components with high resistivity, its resistivity is about two orders of magnitude higher than that of pure copper. Under high current density charging, the negative electrode polarization will be greatly increased, the lithium deposition uniformity will deteriorate, and it will be difficult to suppress the growth of lithium dendrites. Summary of the Invention

[0007] In order to improve the fast charging capability of anode-free batteries, the present invention provides a fast charging negative electrode with high lithium / sodium affinity and high conductivity to address the problems of uneven lithium / sodium deposition, easy formation of dendrites and dead lithium / sodium at high current density in the existing technology. The present invention can improve the affinity of the negative electrode with lithium / sodium, enable lithium / sodium to be uniformly deposited at high current density, inhibit the formation of dendrites, and evenly charge the negative electrode at high current density. 2 It still has a good dendrite inhibition effect under ultra-high current density, which can greatly improve the fast charging capacity retention rate of anode-free batteries.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A fast charging negative electrode, which is an alloy composed of Cu x M y A z , where M is three or more of the elements Zn, Ni, Mn, Sn, Pb, Mg, Al, Ga, Ge, Co, Fe, V, Cr, and Ti; A is one or more of the elements B, Si, P, and Se; x, y, and z are the total molar numbers of the elements Cu, M, and A in the composition, respectively. Calculated as x+y+z=1, x, y, and z satisfy the following relationship: 0.66≤x≤0.89, 0.06≤y≤0.24, 0.04≤z≤0.15, and z≤y. The conductivity of the fast-charging negative electrode is not less than 10mS / m, 100mA / cm 2 The charge capacity retention rate is not less than 50%, and the coulombic efficiency is greater than 98%.

[0010] In the fast-charging negative electrode of the present invention, the role of Cu is to improve the conductivity of the negative electrode, but Cu has a poor affinity for lithium / sodium, so if its content is too high, it will lead to poor affinity for lithium / sodium of the negative electrode, and if its content is too low, it will lead to low conductivity of the negative electrode; the role of M is to improve the alloy uniformity and stability of the negative electrode, but M also has the problem of poor affinity for lithium / sodium, so if its content is too high, it will lead to poor affinity for lithium / sodium of the negative electrode, and if its content is too low, it will lead to poor uniformity and stability of the negative electrode; the role of A is to improve the lithium / sodium affinity of the negative electrode, but A has a very low conductivity, so if its content is too high, it will lead to a decrease in the conductivity of the negative electrode, and if its content is too low, it will lead to poor affinity for lithium / sodium of the negative electrode. By precisely controlling the contents of the three components of Cu, M and A, within the scope of the technical solution provided by the present invention, the three components of Cu, M and A can play a synergistic role, so that the negative electrode has both high lithium affinity and high conductivity.

[0011] Preferably, the molar ratios of the elements in M are equal.

[0012] Preferably, the molar ratios of the elements in A are equal.

[0013] More preferably, the M can be divided into two parts, M1 and M2, wherein M1 is two or more of the elements Zn, Sn, Pb, Al, Mg, Ga, and Ge; and M2 is zero or more of the elements Ni, Mn, Co, Fe, V, Cr, and Ti. M1 and M2 are divided according to their lithium / sodium affinity, with M1 having a better lithium / sodium affinity than M2.

[0014] Further preferably, the element types of M1 are greater than the element types of M2.

[0015] More preferably, the A is an element, preferably 0.04≤z≤0.1.

[0016] More preferably, the A is two elements, preferably 0.06≤z≤0.12.

[0017] More preferably, the A is three or more elements, preferably 0.07≤z≤0.15.

[0018] More preferably, the thickness of the fast-charging negative electrode is 4 to 50 μm. More preferably, the thickness of the fast-charging negative electrode is 5 to 25 μm.

[0019] The present invention also provides a method for preparing the above-mentioned fast-charging negative electrode, comprising the following steps:

[0020] Step 1: Mix the elemental powders of Cu, M and A evenly according to the element ratio in the composition, melt them, and cast them into a block body;

[0021] Step 2: heating the block body, hot rolling, cooling it down, and then cold rolling it to form a sheet;

[0022] Step 3: Annealing the sheet and then cold rolling it twice to make foil;

[0023] Step 4: Annealing the foil to relieve stress, thereby obtaining the fast-charging negative electrode.

[0024] In the above preparation method, in step 2, the temperature is kept at 900-1200° C. for 2-8 hours before hot rolling.

[0025] In the above preparation method, in steps 3 and 4, annealing should be carried out under a protective gas such as nitrogen or argon, with an annealing temperature of 400-600° C. and a holding time of 2-6 hours.

[0026] Based on the above, the present invention also provides an anode-free battery, which includes the fast-charging negative electrode described in the present invention as the negative electrode current collector. Depending on the selection of the positive electrode material and electrolyte in the battery, it can be an anode-free lithium battery or an anode-free sodium battery.

[0027] The main technical ideas of the present invention are as follows:

[0028] The so-called fast charging is to complete charging quickly in a short time, which generally requires a charging rate of more than 4C or a charging current density of 10mA / cm 2 Because the copper current collector used in anode-free batteries has a poor affinity with lithium, lithium deposition is uneven during operation, easily generating dendrites and dead lithium. This is positively correlated with the charging current density, meaning that the higher the charging current density, the worse the lithium deposition uniformity. Existing technologies for improving lithium deposition uniformity have the following two main deficiencies:

[0029] First, although the high conductivity of the negative electrode is maintained, the effect of improving the lithium affinity of the negative electrode is limited. The lithium affinity of the lithium-philic component (such as Zn) is not very good, or the lithium-philic component is too small. It can only improve the lithium deposition uniformity at small and medium current densities, but cannot improve the lithium deposition uniformity at high current density. At high current density, Li + The flux is greatly improved, and a large amount of Li + It needs to be deposited quickly on the negative electrode surface. If the lithium affinity of the negative electrode substrate is poor or there are fewer lithium-affinity active sites, it will lead to uneven lithium deposition.

[0030] Secondly, although the lithium affinity of the negative electrode is greatly improved, the conductivity of the negative electrode is greatly reduced. The electrode polarization is negatively correlated with the electrode conductivity and positively correlated with the current density. Charging at a high current density will greatly increase the polarization of the low-conductivity negative electrode, and the Li + The flow is turbulent, the uniformity of lithium deposition deteriorates, the charging voltage rises rapidly and reaches the charging cut-off voltage, and the battery capacity is greatly reduced.

[0031] After studying various materials and their combinations, the present invention introduces a suitable lithium-philic component into the negative electrode to enhance its lithium affinity. Simultaneously, the ratio of each component in the negative electrode is adjusted to improve its conductivity. Ultimately, a fast-charging negative electrode with both high lithium affinity and high conductivity is produced. This design approach is not found in the prior art.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] 1) The present invention introduces component A with good affinity for lithium / sodium into the negative electrode, thereby improving the affinity of the negative electrode with lithium / sodium, causing lithium / sodium to be uniformly deposited on the surface of the negative electrode current collector, and inhibiting the formation of lithium / sodium dendrites;

[0034] 2) The present invention precisely controls the contents of the three components Cu, M and A. Within the scope of the technical solution provided by the present invention, the three components Cu, M and A can play a synergistic role, so that the negative electrode has both high lithium affinity and high conductivity, even at a high current density of 100 mA / cm 2 It still has a good dendrite suppression effect under ultra-high current density, which can greatly improve the fast charging capacity retention rate of anode-free batteries;

[0035] 3) The preparation method of the present invention is simple, has low overall cost, and can be used for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The charge capacity curves at different current densities for Example 1 and Comparative Example 1 are shown;

[0037] Figure 2 100 mA / cm2 for Example 1 and Comparative Example 1 2 SEM image of the negative electrode charged at a current density of 100 nm. DETAILED DESCRIPTION

[0038] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with examples, but the present invention is not limited to the following examples.

[0039] Example 1

[0040] (1) Preparation of fast-charging negative electrode

[0041] The negative electrode is composed of Cu 0.8 Mg 0.04 Al 0.04 Sn 0.04 Si 0.04 Se 0.04 :

[0042] Step 1: Mix Cu, Mg, Al, Sn, Si, and Se powders in the appropriate element ratio, melt them, and cast them into a block body;

[0043] Step 2: Heat the blank to 1000°C, keep it warm for 5 hours, hot-roll it, and then cold-roll it after cooling it down to make a sheet.

[0044] Step 3: Under argon protection, the sheet is annealed at 500°C for 4 hours, and then cold-rolled twice to form a foil with a thickness of 15 μm.

[0045] Step 4: Under argon protection, the foil is annealed to relieve stress at a temperature of 550°C for 3 hours to obtain the fast-charging negative electrode. The negative electrode is sliced to form a negative electrode sheet.

[0046] (2) Positive electrode preparation

[0047] The positive electrode active material is lithium cobalt oxide, the positive electrode conductive agent is SP, the positive electrode binder is PVDF, and the positive electrode current collector is aluminum foil. The mass ratio of the positive electrode active material, positive electrode conductive agent, and positive electrode binder is 97:1.5:1.5. The positive electrode active material, positive electrode conductive agent, and positive electrode binder are made into a slurry, coated on the positive electrode current collector, and then dried, roll-pressed, and die-cut to form the positive electrode sheet.

[0048] (3) Battery preparation

[0049] Using the negative and positive electrodes prepared in the above steps, a CR2032 button-type anode-free battery was fabricated. The method involved stacking the negative electrode shell, negative electrode sheet, separator (50 μL of electrolyte was added while the separator was in place), positive electrode sheet, gasket, spring, and positive electrode shell in this order, then fastening them together. The separator used a PE / PP double-layer membrane, and the electrolyte was lithium hexafluorophosphate at a concentration of 1 mol / L.

[0050] Example 2

[0051] (1) Preparation of fast-charging negative electrode

[0052] The negative electrode is composed of Cu 0.66 Zn 0.05 Al 0.05 Ge 0.05 Ni 0.05 V 0.05 P 0.03 Si 0.03 Se 0.03 :

[0053] Step 1: Mix Cu, Zn, Al, Ge, Ni, V, P, Si, and Se powders uniformly according to the element ratio in the composition, melt them, and cast them into a block embryo;

[0054] Step 2: Heat the blank to 900°C, keep it warm for 8 hours, hot-roll it, and then cold-roll it after cooling it down to make a sheet.

[0055] Step 3: Under argon protection, the sheet is annealed at 400°C for 6 hours, followed by secondary cold rolling to produce a foil with a thickness of 25 μm.

[0056] Step 4: Under argon protection, the foil is annealed to relieve stress at 450°C for 6 hours to obtain the fast-charging negative electrode. The negative electrode is sliced to form a negative electrode sheet.

[0057] (2) Cathode and battery preparation

[0058] A positive electrode sheet and a battery were prepared according to the method of Example 1.

[0059] Example 3

[0060] (1) Preparation of fast-charging negative electrode

[0061] The negative electrode is composed of Cu 0.73 Mg 0.03 Al 0.03 Zn 0.03 Sn 0.03 Ni 0.03 Co 0.03 P 0.03 Si 0.03 Se 0.03 :

[0062] Step 1: Mix Cu, Mg, Al, Zn, Sn, Ni, Co, P, Si, and Se powders in proportion to the elements in the composition, melt them, and cast them into a block body;

[0063] Step 2: Heat the blank to 1000°C, keep it warm for 5 hours, hot-roll it, and then cold-roll it after cooling it down to make a sheet;

[0064] Step 3: Under argon protection, the sheet is annealed at 500°C for 3 hours, and then cold-rolled twice to form a foil with a thickness of 5 μm.

[0065] Step 4: Under argon protection, the foil is annealed to relieve stress at a temperature of 550°C for 3 hours to obtain the fast-charging negative electrode. The negative electrode is sliced to form a negative electrode sheet.

[0066] (2) Cathode and battery preparation

[0067] A positive electrode sheet and a battery were prepared according to the method of Example 1.

[0068] Example 4

[0069] (1) Preparation of fast-charging negative electrode

[0070] The negative electrode is composed of Cu 0.89 Ge 0.015 Sn 0.015 Al 0.015 Co 0.015 P 0.025 Se 0.025 :

[0071] Step 1: Mix Cu, Ge, Sn, Al, Co, P, and Se powders uniformly according to the element ratio in the composition, melt them, and cast them into a block embryo;

[0072] Step 2: Heat the blank to 1200°C, keep it warm for 2 hours, hot-roll it, and then cold-roll it after cooling it down to make a sheet;

[0073] Step 3: Under argon protection, the sheet is annealed at 600°C for 2 hours, followed by secondary cold rolling to produce a foil with a thickness of 5 μm.

[0074] Step 4: Under argon protection, the foil is annealed to relieve stress at 600°C for 2 hours to obtain the fast-charging negative electrode. The negative electrode is sliced to form a negative electrode sheet.

[0075] (2) Cathode and battery preparation

[0076] A positive electrode sheet and a battery were prepared according to the method of Example 1, except that sodium nickel iron manganese oxide was used as the positive electrode material and sodium hexafluorophosphate was used as the electrolyte.

[0077] Comparative Example 1

[0078] A 10 μm thick pure copper foil was cut into negative electrode sheets, and a positive electrode sheet and a battery were prepared according to the method of Example 1.

[0079] Comparative Example 2

[0080] (1) Negative electrode preparation

[0081] The composition of the negative electrode is CuZn alloy with a Zn content of 5wt%:

[0082] Step 1: Mix Cu and Zn powders evenly according to the element ratio in the composition, melt, and cast into a block body;

[0083] Step 2: Heat the blank to 1000°C, keep it warm for 5 hours, hot-roll it, and then cold-roll it after cooling it down to make a sheet;

[0084] Step 3: Under argon protection, the sheet is annealed at 500°C for 4 hours, and then cold-rolled twice to form a foil with a thickness of 15 μm.

[0085] Step 4: Under argon protection, the foil is annealed to relieve stress at a temperature of 550°C for 3 hours to obtain the fast-charging negative electrode. The negative electrode is sliced to form a negative electrode sheet.

[0086] (2) Cathode and battery preparation

[0087] A positive electrode sheet and a battery were prepared according to the method of Example 1.

[0088] Comparative Example 3

[0089] (1) Negative electrode preparation

[0090] The negative electrode is composed of Cu 0.2 Fe 0.2 Mg 0.2 Mn 0.2 Si 0.2 High Entropy Alloys:

[0091] Step 1: Mix Cu, Fe, Mg, Mn, and Si powders uniformly according to the element ratio in the composition, melt, and cast into a block embryo;

[0092] Step 2: Heat the blank to 1000°C, keep it warm for 5 hours, hot-roll it, and then cold-roll it after cooling it down to make a sheet;

[0093] Step 3: Under argon protection, the sheet is annealed at 500°C for 4 hours, and then cold-rolled twice to form a foil with a thickness of 15 μm.

[0094] Step 4: Under argon protection, the foil is annealed to relieve stress at a temperature of 550°C for 3 hours to obtain the fast-charging negative electrode. The negative electrode is sliced to form a negative electrode sheet.

[0095] (2) Cathode and battery preparation

[0096] A positive electrode sheet and a battery were prepared according to the method of Example 1.

[0097] Comparative Example 4

[0098] (1) Negative electrode preparation

[0099] The composition of the negative electrode is CuSnCrZnMgAlSiP alloy, in which the content of each component is Cu 96.78wt%, Sn 1.5wt%, Cr 0.3wt%, Zn 0.12wt%, Mg 0.25wt%, Al 0.35wt%, Si 0.55wt%, P0.15wt%:

[0100] Step 1: Mix Cu, Sn, Cr, Zn, Mg, Al, Si, and P powders uniformly according to the element ratio in the composition, melt, and cast into a block embryo;

[0101] Step 2: Heat the blank to 1000°C, keep it warm for 5 hours, hot-roll it, and then cold-roll it after cooling it down to make a sheet;

[0102] Step 3: Under argon protection, the sheet is annealed at 500°C for 4 hours, and then cold-rolled twice to form a foil with a thickness of 15 μm.

[0103] Step 4: Under argon protection, the foil is annealed to relieve stress at a temperature of 550°C for 3 hours to obtain the fast-charging negative electrode. The negative electrode is sliced to form a negative electrode sheet.

[0104] (2) Cathode and battery preparation

[0105] A positive electrode sheet and a battery were prepared according to the method of Example 1.

[0106] Performance Testing

[0107] The electrical conductivities of the negative electrodes prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were tested, and the results are shown in Table 1.

[0108] Table 1 Conductivity test data

[0109]

[0110] The CR2032 button batteries prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were respectively 2 , 10mA / cm 2 , 100mA / cm 2 The current density is charged and discharged. The charge and discharge voltage range of Examples 1 to 3 and Comparative Examples 1 to 4 is 2.75 to 4.3 V, and the charge and discharge voltage range of Example 4 is 1.5-4.1 V. The test results are shown in FIG. Figure 1 、 Figure 2 and Table 2 and Table 3.

[0111] Among them, 100mA / cm 2 Charge capacity retention rate = 100mA / cm 2 Charge specific capacity / 1mA / cm 2 Charge capacity*100%.

[0112] Table 2 Test data of different current densities

[0113]

[0114]

[0115] Table 3 100mA / cm 2 Charge and discharge test data sheet

[0116]

[0117] from Figure 1 As can be seen from the data in Tables 2 and 3, the batteries obtained in Examples 1 to 4 all have good fast charging performance. Examples 1 to 4 can charge more than 50% of their capacity in only about 50 seconds, and the coulombic efficiency is greater than 98%. The main reason is that the examples use the fast-charging negative electrode described in the present invention. The Cu, M, and A components can synergistically induce uniform lithium / sodium deposition and inhibit the formation of dendrites, thereby significantly improving the fast charging performance of the battery.

[0118] from Figure 2 As can be seen from the figure, the lithium deposited on the negative electrode of Example 1 is in the form of flat blocks with good uniformity and almost no dendrites; while the lithium deposited on the negative electrode of Comparative Example 1 is in the form of fine dendrites with dendrites covering the surface of the negative electrode. This shows that the present invention has a good performance at 100mA / cm 2 Even at ultra-high current density, the uniformity of lithium deposition can be improved and dendrite growth can be inhibited.

[0119] The negative electrode of Comparative Example 1 uses pure copper foil, which has poor lithium affinity and forms a large amount of dendrites and dead lithium during the charge and discharge process (see Figure 2 ), resulting in increased polarization of the negative electrode, quickly reaching the charge and discharge cut-off voltage, and a significant decrease in battery capacity. 2 It is almost impossible to charge and discharge at a current density of 100 nm, and the fast charging performance is extremely poor.

[0120] The negative electrode of Comparative Example 2 uses CuZn alloy with a Zn content of 5wt%. Its conductivity is very high, but due to the poor lithium affinity of Zn, its fast charging performance is very poor. 2 The charge capacity retention rate at the current density of is only 20.5%, and the coulombic efficiency is only 12.6%, which are much lower than those in the embodiment.

[0121] High entropy alloy is a new material developed in recent years. It can be added with lithium-philic elements to improve the lithium-philic effect of the material. However, in order to maintain the high entropy state and uniformity of the material, the molar ratio of all elements must be equal. The addition of a large amount of low conductivity elements will cause the conductivity of the high entropy alloy to drop significantly. 0.2 Fe 0.2 Mg 0.2 Mn 0.2 Si 0.2 The high entropy alloy contains up to 20% molar ratio of low conductivity element Si, which results in a very low conductivity of the negative electrode (only 0.2mS / m), resulting in poor fast charging performance. 2 At a current density of , the cut-off voltage is reached after only 5s of charging, the charging capacity retention rate is only 5.6%, and the coulombic efficiency is only 7.2%, which are much lower than those in the embodiment.

[0122] The negative electrode of Comparative Example 4 adopts CuSnCrZnMgAlSiP alloy, wherein the content of each component is Cu 96.78wt%, Sn 1.5wt%, Cr 0.3wt%, Zn 0.12wt%, Mg 0.25wt%, Al 0.35wt%, Si 0.55wt%, P0.15wt%, at 100mA / cm 2 The charge capacity retention rate at the current density is only 13%, and the coulombic efficiency is only 9.8%, which are much lower than those in the embodiment. This may be because the content of the lithium-philic component is too low (the content of Si+P is only 0.7wt%), resulting in poor lithium-philic effect.

[0123] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, several improvements and changes can be made without departing from the creative concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A fast-charging negative electrode, characterized in that: The conductivity of the fast-charging negative electrode is not less than 10mS / m; The composition of the fast charging negative electrode is Cu x M y A z , wherein M is three or more of the elements Zn, Ni, Mn, Sn, Pb, Mg, Al, Ga, Ge, Co, Fe, V, Cr, and Ti; A is one or more of the elements B, Si, P, and Se; x, y, and z satisfy the following relationship: x+y+z=1, 0.66≤x≤0.89, 0.06≤y≤0.24, 0.04≤z≤0.15, z≤y.

2. The fast-charging negative electrode according to claim 1, characterized in that The M includes M1 and M2, wherein M1 is two or more of the elements Zn, Sn, Pb, Al, Mg, Ga, and Ge; and M2 is one or more of the elements Ni, Mn, Co, Fe, V, Cr, and Ti.

3. The fast-charging negative electrode according to claim 1, characterized in that The M is M1, wherein M1 is three or more of the elements Zn, Sn, Pb, Al, Mg, Ga, and Ge.

4. The fast-charging negative electrode according to claim 1, characterized in that A is an element, 0.04≤z≤0.

1.

5. The fast-charging negative electrode according to claim 1, characterized in that The A is two elements, 0.06≤z≤0.

12.

6. The fast-charging negative electrode according to claim 1, characterized in that The A is three or more elements, 0.07≤z≤0.

15.

7. The fast-charging negative electrode according to claim 1, characterized in that: The thickness is 4 to 50 μm.

8. The method for preparing the fast-charging negative electrode according to claim 1, characterized in that: The following steps are involved: Step 1: Mix the elemental powders of Cu, M and A evenly according to the element ratio in the composition, melt them, and cast them into a block body; Step 2: heating the block body, hot rolling, cooling it down, and then cold rolling it to form a sheet; Step 3: Annealing the sheet and then cold rolling it twice to make foil; Step 4: Annealing the foil to relieve stress, thereby obtaining the fast-charging negative electrode.

9. The method for preparing a fast-charging negative electrode according to claim 7, characterized in that: Before hot rolling in step 2, the temperature is kept at 900-1200° C. for 2-8 hours; and the annealing in steps 3 and 4 is carried out under a protective atmosphere.

10. Use of the fast-charging negative electrode according to any one of claims 1 to 7 in an anode-free battery, wherein the anode-free battery is an anode-free lithium battery or an anode-free sodium battery.

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