CN106602036A - Carbon core/copper oxide housing composite electrode for lithium ion battery and preparation method thereof - Google Patents

Abstract

The invention discloses a carbon core/copper oxide housing composite electrode for a lithium ion battery and a preparation method thereof. A core part of the carbon core/copper oxide housing composite electrode is formed by carbon fibers, and a housing of the carbon core/copper oxide housing composite electrode is a copper oxide thin layer; and the copper oxide thin layer is provided with nano needle-shaped structures and nano pore-shaped structures, which are arranged in an array mode. The preparation method of the carbon core/copper oxide housing composite electrode comprises the following steps of: (1) preparation of copper-coated carbon fibers; (2) sintering moulding of the copper-coated carbon fibers; and (3) surface oxidation treatment of a formed copper-coated carbon fiber felt. According to the carbon core/copper oxide housing composite electrode disclosed by the invention, charging and discharging capacity of the lithium ion battery is improved, and electrochemical properties of a cycle life, coulombic efficiency, cycling stability and the like of the lithium ion battery are improved.

Description

A carbon core/copper oxide shell composite electrode for lithium-ion batteries and its preparation method

technical field

The invention relates to the technical field of lithium ion batteries, in particular to a carbon core/copper oxide shell composite electrode for lithium ion batteries and a preparation method thereof.

Background technique

Lithium-ion battery is a green high-energy rechargeable chemical power source, which has outstanding advantages such as high voltage, high energy density, good cycle performance, small self-discharge, and no memory effect. It has been widely used in defense industry and other fields.

Carbon materials are currently the most widely used negative electrode materials in lithium-ion batteries. They have suitable lithium intercalation potential (0.15~0.25V), good conductivity, stable cycle, rich resources and low price, and have long become the mainstream of the market. However, the theoretical specific capacity of carbon materials is low (372mAh·g ^-1 ), which can no longer meet people's high demand for energy. Therefore, people urgently need new active materials with good lithium storage performance and high theoretical capacity to replace traditional graphite materials. It is applied in the field of lithium-ion batteries to solve the embarrassing situation that energy is in short supply. Due to the advantages of good lithium storage performance, high theoretical capacity, simple preparation, and wide source of raw materials, transition metal oxides have aroused strong interest of researchers at home and abroad. Copper oxide, as the most common transition metal oxide, has been gradually used in lithium-ion batteries due to its high theoretical specific capacity (674mAh·g ^-1 ), simple preparation, and low cost. However, the conductivity of copper oxide is poor, so the application of pure copper oxide as the negative electrode active material in lithium-ion batteries will inevitably lead to a decrease in the cycle life, Coulombic efficiency, and charge-discharge stability of the battery. In order to solve this problem, the majority of researchers currently improve the comprehensive performance of batteries with copper oxide as the negative electrode active material by adding conductive additives, synthesizing composite materials, and modifying the form of active materials. For example, the conductivity of electrodes can be improved by adding conductive materials such as conductive graphite, carbon nanotubes, and metal powders, and the cycle life and reversible capacity of batteries can be improved by synthesizing structures such as CuO composite nanowires, nanorods, and nanoflowers. These methods have solved to a certain extent the problem of poor electrical conductivity of CuO leading to the degradation of battery performance.

In addition, during the cycle charge and discharge process of lithium-ion batteries, the process of lithium intercalation and delithiation inside the active material will inevitably cause the expansion and contraction of the particle volume of the active material, which will cause the pulverization of the electrode material and affect the cycle life of the battery. . Therefore, limiting the volume change of the active material during lithium intercalation and delithiation is undoubtedly an effective means to prolong the cycle life of the battery and improve the overall performance of the battery. For example, some researchers limit the drastic volume change of silicon particles during battery charging and discharging by carbonizing a thin layer of carbon on the surface of silicon particles, thereby improving the cycle life and reversible capacity of batteries. Some scholars have metallized the surface of silicon particles by electroless copper plating, thereby improving the electrochemical performance of lithium-ion batteries.

Contents of the invention

In order to improve the conductivity of the electrode when CuO is used as the negative electrode material of the battery, limit the volume change of the carbon-based active material in the charging and discharging process of the battery, thereby improving the electrochemical properties such as the reversible capacity, cycle life, and charge-discharge stability of the battery. Provided is a carbon core/copper oxide shell composite electrode for lithium ion batteries.

The invention also provides a preparation method of the carbon core/copper oxide shell composite electrode for lithium ion batteries.

The present invention is realized through the following technical solutions.

A carbon core/copper oxide shell composite electrode for lithium-ion batteries, the core is carbon fiber, and the shell is a thin layer of copper oxide; the thin layer of copper oxide has an array-type nano-needle structure and a nano-pore structure; The nano-acicular structure is on the outer surface of the copper oxide thin layer, and the nano-porous structure is a hole penetrating through the copper oxide thin layer.

The method for preparing a carbon core/copper oxide shell composite electrode for lithium ion batteries includes preparation of copper-coated carbon fibers, sintering of copper-coated carbon fibers and surface oxidation treatment of formed copper-coated carbon fiber mats.

Further, the preparation of the copper-plated carbon fiber comprises the following steps:

(1) Surface degumming: place the carbon fiber in a high-temperature resistance furnace and burn it in the air to remove the protective glue on the surface of the carbon fiber, improve the bonding force between the coating and the carbon fiber, and reduce the contact resistance between the coating and the carbon fiber;

(2) Surface roughening: Soak the burnt carbon fiber in (NH ₄ ) ₂ S ₂ O ₈ solution with ultrasonic waves to make the surface of the carbon fiber rough and hydrophilic; then soak it in NaOH solution to remove the residue on the surface of the carbon fiber (NH ₄ ) ₂ S ₂ O ₈ , and then washed with deionized water;

(3) Surface sensitization: Soak the roughened carbon fiber in a sensitization solution prepared by SnCl ₂ , HCl and H ₂ O, and then rinse it with deionized water;

(4) Surface activation: soak the sensitized carbon fiber in an activation solution prepared by AgNO ₃ , NH ₃ H ₂ O and H ₂ O, and then clean the carbon fiber to black with deionized water;

(5) Copper plating on the surface: place the activated carbon fiber in a plating solution prepared by NaKC ₄ H ₄ O ₆ 4H ₂ O, CuSO ₄ 5H ₂ O, HCHO, NaOH and H ₂ O, and use magnetic Stir with a stirrer until no bubbles are generated in the solution, and finally wash with deionized water and dry in vacuum to obtain the copper-plated carbon fiber.

Furthermore, in step (1), the length of the carbon fiber is 1-2 mm.

Furthermore, in step (1), the burning is burning at 400-500° C. for 30-40 minutes.

Furthermore, in step (2), the concentration of the (NH ₄ ) ₂ S ₂ O ₈ solution is 15-17wt%.

Furthermore, in step (2), the ultrasonic soaking time in (NH ₄ ) ₂ S ₂ O ₈ solution is 30-40 minutes.

Furthermore, in step (2), the concentration of the NaOH solution is 9-11wt%.

Furthermore, in step (2), the soaking time in NaOH solution is 5-10 minutes.

Furthermore, in step (2), the deionized water washing is performed until the washing liquid is neutral.

Furthermore, in step (3), in the sensitization solution prepared by SnCl ₂ , HCl and H ₂ O, the concentration of SnCl ₂ is 0.01-0.02 g·mL ^-1 , and the concentration of HCl is 38-40 mL· L ^-1 .

Furthermore, in step (3), the soaking time is 5-10 minutes.

Furthermore, in step (3), the number of times of rinsing with static water is 3 to 4 times.

Furthermore, in step (4), in the activation solution prepared from AgNO ₃ , NH ₃ ·H ₂ O and H ₂ O, the concentration of AgNO ₃ is 0.004~0.005g·mL ^-1 , and the concentration of NH ₃ 9~10mL·L ^-1 .

Furthermore, in step (4), the soaking time is 5-10 minutes.

Further, in step (5), in the plating solution prepared by NaKC ₄ H ₄ O ₆ 4H ₂ O, CuSO ₄ 5H ₂ O, HCHO, NaOH and H ₂ O, NaKC ₄ H ₄ O ₆ The concentration of CuSO 4 is 0.04~0.05g·mL ^-1 , the concentration of CuSO ₄ is 0.01~0.02g·mL ^-1 , the concentration of HCHO is 9~10mL·L ^-1 , and the concentration of NaOH is 0.01~0.02 g·mL ^-1 .

Furthermore, in step (5), the stirring speed of the magnetic stirrer is 300~400r·min ⁻¹ .

Furthermore, in step (5), the deionized water washing is performed until the washing liquid is neutral.

Furthermore, in step (5), the vacuum drying is carried out at 50-60° C. for 5-6 hours.

Further, the sintering molding of the copper-coated carbon fiber includes the following steps:

The copper-coated carbon fiber is pressed into a fiber felt with a mold, placed in a vacuum resistance furnace, and sintered at high temperature to obtain a shaped copper-coated carbon fiber felt.

Furthermore, the carbon fiber felt has a diameter of 14-15mm and a thickness of 0.1-0.2mm.

Furthermore, the sintering is carried out under a hydrogen atmosphere.

Furthermore, the sintering temperature is 750-800° C., and the sintering time is 60-70 minutes.

Further, the surface oxidation treatment of the shaped copper-clad carbon fiber felt includes the following steps:

The formed copper-coated carbon fiber felt is placed in a muffle furnace, and heated and oxidized at a high temperature in an air atmosphere to obtain the carbon core/copper oxide shell composite electrode for lithium-ion batteries.

Furthermore, the temperature of the heating oxidation is 400-450° C., and the time is 1-2 hours.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) In the carbon core/copper oxide shell composite electrode used in the lithium ion battery of the present invention, the nanoporous structure of the copper oxide thin layer is conducive to the easy passage of lithium ions in the electrolyte, and then lithium intercalation and Delithiation process, thereby increasing the charge and discharge capacity of lithium-ion batteries;

(2) The present invention is used in the carbon core/copper oxide shell composite electrode of lithium-ion batteries. The carbon core part is in close contact with the copper oxide shell, which not only improves the conductivity of the electrode, but also buffers the volume change during the copper oxide conversion process ;

(3) The carbon core/copper oxide shell composite electrode of the present invention is used for lithium ion batteries. The copper oxide shell tightly wraps the carbon core, and the nano-needle structure of the copper oxide shell greatly shortens the diffusion distance and The effective contact area with lithium ions is increased, and the expansion of carbon fiber volume during charging and discharging lithium intercalation and delithiation processes of lithium ion batteries is limited, which is conducive to improving the reversible capacity and cycle life of lithium ion batteries.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the carbon core/copper oxide shell composite electrode prepared in embodiment 1;

Fig. 2 is the local schematic diagram of the carbon core/copper oxide shell composite electrode prepared in embodiment 1;

Fig. 3 is the assembly schematic diagram of the lithium-ion half cell that carbon core/copper oxide shell composite electrode is housed in embodiment 2;

FIG. 4 is a graph showing cycle charge and discharge test curves of a lithium-ion half-cell equipped with a carbon core/copper oxide shell composite electrode in Example 2. FIG.

detailed description

In order to further understand the present invention, the present invention will be further described below in conjunction with the accompanying drawings and examples, but it should be noted that the scope of protection claimed by the present invention is not limited to the scope expressed in the examples, and other parameters not listed in the scope of the claims Examples are equally valid.

Example 1

A preparation of a carbon core/copper oxide shell composite electrode for lithium ion batteries, comprising the steps of:

Preparation of copper-coated carbon fibers

(1) Surface degumming: Put the carbon fiber with a length of 1 mm in the air in a high-temperature resistance furnace and burn for 30 minutes at a temperature of 400°C to remove the protective glue on the surface of the carbon fiber, improve the bonding force between the coating and the carbon fiber, and reduce the contact resistance between the coating and the carbon fiber;

(2) Surface roughening: The carbon fibers after degumming were placed in (NH ₄ ) ₂ S ₂ O ₈ solution with a concentration of 15wt% and ultrasonically soaked for 30 minutes to make the surface of the carbon fibers rough and hydrophilic; Soak it in 10wt% NaOH solution for 5 minutes to remove the residual (NH ₄ ) ₂ S ₂ O ₈ on the surface of the carbon fiber, and wash the carbon fiber until the washing solution is neutral;

(3) Surface sensitization: place the roughened carbon fiber in a sensitization solution prepared by SnCl ₂ , HCl and H ₂ O (in the sensitization solution, the concentration of SnCl ₂ is 0.02g·mL ^-1 , HCl concentration of 40mL·L ^-1 ) for 10min, and then rinse the carbon fiber with deionized water for 3 times;

(4) Surface activation: place the sensitized carbon fibers in an activation solution prepared from AgNO ₃ , NH ₃ H ₂ O and H ₂ O (in the activation solution, the concentration of AgNO ₃ is 0.005g·mL ^-1 , the concentration of NH ₃ ·H ₂ O is 10mL·L ^-1 ) for 10min, and then wash the carbon fiber with deionized water until it is black;

(5) Copper plating on the surface: place the activated carbon fiber in a plating solution prepared by NaKC ₄ H ₄ O ₆ 4H ₂ O, CuSO ₄ 5H ₂ O, HCHO, NaOH and H ₂ O (in the plating solution , the concentration of NaKC ₄ H ₄ O ₆ is 0.04g·mL ^-1 , the concentration of CuSO ₄ is 0.01g·mL ^-1 , the concentration of HCHO is 10mL·L ^-1 , and the concentration of NaOH is 0.01g·mL ^-1 ) In the process, stir with a magnetic stirrer at a speed of 400r min ^-1 until the solution has no bubbles, and finally wash the copper-coated carbon fiber with deionized water until the washing solution is neutral, and dry it in vacuum at 60°C for 6h to obtain the copper-coated carbon fiber .

Sintering Forming of Copper-coated Carbon Fiber

(6) Compression: Press 50mg of copper-plated carbon fiber into a fiber mat with a diameter of 15mm and a thickness of 0.1mm;

(7) Sintering: Place the pressed fiber mat in a vacuum resistance furnace, sinter at high temperature under hydrogen atmosphere, the sintering temperature is 800°C, and the holding time is 60min to obtain a shaped copper-coated carbon fiber mat.

Surface Oxidation Treatment of Formed Copper-clad Carbon Fiber Felt

(8) Put the obtained formed copper-coated carbon fiber felt in a muffle furnace, heat and oxidize it in the air at a high temperature, the heating temperature is 400°C, and the holding time is 2h, to obtain the carbon core/copper oxide for lithium-ion batteries Shell composite electrodes.

The overall structural schematic diagram and partial schematic diagram of the prepared carbon core/copper oxide shell composite electrode for lithium-ion batteries are shown in Figure 1 and Figure 2, respectively, including the core and the shell, the core is made of carbon fiber 11, and the shell is made of copper oxide thin film layer; the copper oxide thin layer has an array-type nano-needle structure 9 and a nano-porous structure 10, the nano-acicular structure 9 is on the outer surface of the copper oxide thin layer, and the nano-porous structure 10 is a hole penetrating the copper oxide thin layer.

Example 2

The schematic diagram of assembling the carbon core/copper oxide shell composite electrode prepared in Example 1 into a lithium-ion half-cell is shown in Figure 3, including an upper battery case 1, a shrapnel 2, a gasket 3, a lithium sheet 4, a diaphragm 5, and an electrolyte 6. Lower battery shell 7 and carbon core/copper oxide shell composite electrode 8;

The carbon core/copper oxide shell composite electrode 8 is placed on the lower battery shell 7, and the electrolyte 6 fills the entire cavity composed of the carbon core/copper oxide shell composite electrode 8, the lower battery shell 7 and the diaphragm 5, and the entire cavity is filled with There are active substances, and the electrolyte 6 directly infiltrates the active substances on the carbon core/copper oxide shell composite electrode 8; the lithium sheet 4 is closely attached to the diaphragm 5, and the upper surface of the lithium sheet 4 is placed in sequence from bottom to top. Gasket 3 and shrapnel 2. Gasket 3 and shrapnel 2 play the role of adjusting the pressure. Shrapnel 2 is in close contact with upper battery case 1 to reduce contact resistance and ensure good electrical conductivity inside the battery.

After the lithium-ion half-cell is assembled, when it is discharged, the lithium sheet 4 begins to delithiate, and the lithium ions enter the electrolyte 6 through the diaphragm 5, and then contact the active material on the carbon core/copper oxide shell composite electrode 8 to undergo transformation. The specific performance is that lithium ions are directly converted with 9 through the electrolyte, and then pass through the nanostructure 10 and then intercalate with 11; at the same time, electrons enter the lower battery through the gasket 3, the shrapnel 2 and the upper battery case 1. Shell 7, because the lower battery shell 7 is in close contact with the carbon core/copper oxide shell composite electrode 8, so electrons enter the active material of the carbon core/copper oxide shell composite electrode 8 to neutralize the charge with lithium ions, completing the lithium ion half The discharge process of the battery; and the charging process of the lithium-ion half-cell is just the opposite.

During the charging and discharging process of the lithium-ion half-battery, since the nano-needle structure of the copper oxide shell greatly shortens the diffusion distance of lithium ions and increases the effective contact area with lithium ions, the reversible capacity of the battery can be be greatly improved. In addition, the nanoporous structure of copper oxide is conducive to the easy passage of lithium ions in the electrolyte, and then lithium intercalation and delithiation processes occur in the carbon core, thereby increasing the charge and discharge capacity of the battery. During the cycle charge and discharge process of the battery, the carbon core part is in close contact with the copper oxide shell, which not only improves the conductivity of the electrode, but also buffers the volume change during the conversion of copper oxide; the copper oxide shell tightly wraps the carbon core part , to a certain extent limit the volume change of the carbon core during lithium intercalation and delithiation, which is beneficial to improve the reversible capacity and cycle life of the battery.

Using the LAND battery test system CT2001A to conduct cycle charge and discharge tests on the assembled lithium-ion half-cells, the obtained test curves are shown in Figure 4. It can be seen from the curve that the lithium-ion battery with carbon core/copper oxide shell composite electrode (CuO-CF) has a higher reversible capacity than the lithium-ion battery with only copper oxide electrode (CuO) and only carbon fiber electrode (CF) and better magnification performance. Among them, the lithium-ion battery with carbon core/copper oxide shell composite electrode has a reversible specific capacity of 671.2mAh/g under the current condition of 0.1C, which is much higher than that of lithium-ion batteries with only copper oxide electrodes and carbon fiber electrodes. Under different rate conditions, the reversible capacity of lithium-ion batteries with carbon core/copper oxide shell composite electrodes is also extremely superior to that of the other two batteries. In addition, after charging and discharging at 0.1C, 0.2C, 0.5C, 1C and 2C rates, the lithium-ion battery with carbon core/copper oxide shell composite electrode still maintains a reversible capacity of 637.4 mAh/g under the current condition of 0.1C, It accounts for 94.8% of the stable capacity of the battery before charging and discharging at a rate. The results show that the carbon core/copper oxide shell composite electrode can effectively improve the electrochemical performance of lithium-ion batteries.

The above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (10)

1. A carbon core/copper oxide shell composite electrode for lithium-ion battery, characterized in that, the core of the carbon core/copper oxide shell composite electrode is carbon fiber, and the shell is a copper oxide thin layer; The copper thin layer has an array-type needle-like structure and a hole-like structure; the needle-like structure and the hole-like structure are both nanoscale structures; the needle-like structure is on the outer surface of the copper oxide thin layer, and the hole-like structure It is a hole through the thin layer of copper oxide. 2. the preparation method of a kind of carbon core/copper oxide shell composite electrode that is used for lithium-ion battery according to claim 1, is characterized in that, comprises the preparation of copper-plated carbon fiber, the sintering molding of copper-plated carbon fiber and the molding copper-plated carbon fiber Surface oxidation treatment of felt. 3. the preparation method of a kind of carbon core/copper oxide shell composite electrode for lithium ion battery according to claim 2, is characterized in that, the preparation of described copper-plated carbon fiber comprises the steps: (1) Surface glue removal: place the carbon fiber in the air in a high-temperature resistance furnace and burn it in the air to remove the protective glue on the surface of the carbon fiber; (2) Surface roughening: The burned carbon fiber is ultrasonically soaked in (NH ₄ ) ₂ S ₂ O ₈ solution, and then soaked in NaOH solution to remove the residual (NH ₄ ) ₂ S ₂ O ₈ on the surface of the carbon fiber. Then rinse with deionized water; (3) Surface sensitization: Soak the roughened carbon fiber in a sensitization solution prepared by SnCl ₂ , HCl and H ₂ O, and then rinse it with deionized water; (4) Surface activation: soak the sensitized carbon fiber in an activation solution prepared by AgNO ₃ , NH ₃ H ₂ O and H ₂ O, and then clean the carbon fiber to black with deionized water; (5) Copper plating on the surface: place the activated carbon fiber in a plating solution prepared by NaKC ₄ H ₄ O ₆ 4H ₂ O, CuSO ₄ 5H ₂ O, HCHO, NaOH and H ₂ O, and use magnetic Stir with a stirrer until no bubbles are generated in the solution, and finally wash with deionized water and dry in vacuum to obtain the copper-plated carbon fiber. 4. A method for preparing a carbon core/copper oxide shell composite electrode for a lithium-ion battery according to claim 3, wherein in step (1), the length of the carbon fiber is 1-2mm, and the The above-mentioned burning is burning at 400-500°C for 30-40min; in step (2), the concentration of the (NH ₄ ) ₂ S ₂ O ₈ solution is 15-17wt%, in (NH ₄ ) ₂ S ₂ The time of ultrasonic immersion in O ₈ solution is 30～40min, and the concentration of described NaOH solution is 9～11wt%, and the time of immersion in NaOH solution is 5～10min, and described deionized water cleaning is to clean until washing liquid is medium sex. 5. A method for preparing a carbon core/copper oxide shell composite electrode for lithium-ion batteries according to claim 3, characterized in that, in step (3), it is prepared from SnCl ₂ , HCl and H ₂ O In the sensitized solution, the concentration of SnCl ₂ is 0.01~0.02g·mL ^-1 , the concentration of HCl is 38~40mL·L ^-1 ; the soaking time is 5~10min, and the times of rinsing with static water are 3~4 times; in step (4), in the activation solution prepared by AgNO ₃ , NH ₃ ·H ₂ O and H ₂ O, the concentration of AgNO ₃ is 0.004~0.005g·mL ^-1 , the concentration of NH ₃ The concentration is 9~10mL·L ^-1 ; the soaking time is 5~10min. 6. A method for preparing a carbon core/copper oxide shell composite electrode for lithium-ion batteries according to claim 3, characterized in that, in step (5), NaKC ₄ H ₄ O ₆ ·4H ₂ O , CuSO ₄ ·5H ₂ O, HCHO, NaOH and H ₂ O, the concentration of NaKC ₄ H ₄ O ₆ is 0.04~0.05g·mL ^-1 , the concentration of CuSO ₄ is 0.01~0.02g · mL ^-1 , the concentration of HCHO is 9~10mL·L ^-1 , the concentration of NaOH is 0.01~0.02 g·mL ^-1 ; the stirring speed of the magnetic stirrer is 300~400r·min ^-1 ; Ionized water cleaning is to wash until the washing liquid is neutral; the vacuum drying is to dry at 50-60°C for 5-6 hours. 7. A kind of preparation method for the carbon core/copper oxide shell composite electrode of lithium-ion battery according to claim 2, is characterized in that, described copper-plated carbon fiber sintering molding, comprises the steps: The copper-coated carbon fiber is pressed into a fiber felt with a mold, placed in a vacuum resistance furnace, and sintered at high temperature to obtain a shaped copper-coated carbon fiber felt. 8. A kind of preparation method for the carbon core/copper oxide casing composite electrode of lithium ion battery according to claim 7, it is characterized in that, the diameter of described copper-plated carbon fiber felt is 14～15mm, and thickness is 0.1～ 0.2 mm; the sintering is carried out under a hydrogen atmosphere; the sintering temperature is 750-800° C., and the sintering time is 60-70 minutes. 9. A kind of preparation method for the carbon core/copper oxide shell composite electrode of lithium-ion battery according to claim 2, is characterized in that, the surface oxidation treatment of described forming copper-plated carbon fiber felt, comprises the steps: The formed copper-coated carbon fiber felt is placed in a muffle furnace, and heated and oxidized at a high temperature in an air atmosphere to obtain the carbon core/copper oxide shell composite electrode for lithium-ion batteries. 10. A method for preparing a carbon core/copper oxide shell composite electrode for lithium-ion batteries according to claim 9, characterized in that the heating and oxidation temperature is 400-450°C, and the time is 1-2h .