CN101702375A - A kind of preparation method of element-doped manganese dioxide electrode material for supercapacitor - Google Patents

Abstract

The invention discloses a method for preparing an element-doped manganese dioxide electrode material for a supercapacitor, which is characterized in that the method comprises the following steps: (1) Synthesizing LiA _x Mn _2- with a spinel structure by a suitable method _x O ₄ powder material; wherein A is selected from Ti, Ni, Sn, Co, Zn, Al metal addition elements, and x is in the range of 0.01 to 0.25%; (2) LiA _x Mn _2- The _x O ₄ powder material was delithiated using a lithium ion extraction agent under the condition of not destroying the precursor spinel configuration to obtain an element substitution-doped MnO ₂ electrode material for supercapacitors. The element-doped manganese dioxide electrode material prepared by this method, the Mn in the crystal lattice is partially replaced by the doping element, and the doping element is uniformly replaced, the method has a high degree of industrialization maturity, and is a very potential supercapacitor oxidation Preparation route of manganese electrode material.

Description

A kind of preparation method of element-doped manganese dioxide electrode material for supercapacitor

technical field

The invention belongs to the technical field of preparation of supercapacitor electrode materials, and in particular relates to a preparation method for replacing doped manganese dioxide with elements for supercapacitors.

Background technique

Supercapacitor is a new type of energy storage element between traditional capacitors and batteries. It has both the advantages of high power density of conventional capacitors and high energy density of rechargeable batteries. It can release large currents instantly, charge and discharge quickly, and has high charging efficiency, long cycle life, no memory effect, basically no maintenance during use, and environmental protection. Pollution-free, it has extremely important and broad application prospects in mobile communications, information technology, industrial fields, consumer electronics, electric vehicles, aerospace and defense technology, etc.

At present, the electrode materials used for supercapacitors mainly include: carbon electrode materials, metal oxides and their hydrate electrode materials, and conductive polymer electrode materials. Carbon electrode materials are mainly based on the principle of electric double layer to store energy, and the specific capacitance is relatively low;

Conductive polymer materials mainly generate Faraday quasi-capacitance to store energy through the rapid reversible n-type and p-type element doping and dedoping redox reactions in the polymer on the electrode. Although the specific capacitance is high, its n-type doping It is often unstable, and its own expansion and contraction during charging and discharging can lead to its degradation. The stability problem in long-term cycling is difficult to solve, and its application is limited. Metal oxides have attracted much attention due to their quasi-Faraday capacitance characteristics and high specific capacitance. Among them, the specific capacity of RuO ₂ prepared by the sol-gel method is as high as 768F/g, but the price of RuO ₂ is expensive, which limits its research and application.

Manganese oxide (MnO ₂ ) has similar properties to RuO ₂ , and manganese oxide (MnO ₂ ) also has the advantages of abundant resources, low price, and environmental friendliness. The manganese in it can have multiple oxidation valences such as +1, +2, +3, +4, +6, +7, etc., and the crystal structure is also arranged according to the [MnO ₆ ] structural unit, and there are one-dimensional tunnels, two-dimensional A variety of pore structures such as layered and three-dimensional networks are extremely potential electrode materials for supercapacitors.

However, since MnO ₂ itself is a semiconductor, as an electrode material, its ability to conduct electrons is weak, and its performance has been greatly restricted. For example, Wang[XYWang et.al, J.Power Source140(2005)211-215.] and Yue[GHYue et.al, J.Crystal Growth 294(2006)385-388.] used sol-gel template method and solvent Highly ordered MnO ₂ nanowire arrays and single crystal MnO ₂ nanowires were synthesized by thermal method, and their supercapacitive performance was not much improved compared with ordinary MnO ₂ electrode materials, and the specific capacitance did not exceed 200F/g.

Doping, as an important technical means to affect the material structure and shape the material structure to improve the performance of the material, is of great significance to the modification of the chemical power electrode material, and is a very promising solution and way to improve the performance of the material . Recently, Machefaux et al. [E.Machefauxet.al, J.Powersourcs 165(2007)651-655.] showed that the γ-Mn _{1 -y} A _y O _2-δ ( A=Co, Al) The electrochemical performance of the electrode material is significantly improved. It can be seen that element doping of MnO ₂ is an important way to improve the electrochemical performance of its supercapacitor. However, Machefaux used a combination of electrochemical and hydrothermal reactions to prepare the element-doped MnO ₂ electrode material. The method is cumbersome and complicated, and the control conditions are high, which is not conducive to large-scale production.

Aiming at the problems existing in the Machefaux method, Chinese patent application CN101409152A disclosed on April 15, 2009 a preparation method for element-doped manganese dioxide electrode materials for supercapacitors, namely: Al, Ti, Any one of Ni and Fe is put into a high-energy ball mill jar after being mixed according to the atomic ratio of 0.05:0.95 of manganese in manganese dioxide, and agate balls with different diameters are selected as the ball milling medium, and the ball-to-material ratio is 20:1; Add anti-caking agent ethanol, mill at a ball milling speed of 250 rpm for 15 hours; take out the product after the ball mill tank is cooled to room temperature, and dry it in a drying oven at a constant temperature of 80°C for 48 hours; then dry the dried powder with agate By grinding in a mortar and mortar, the element substitution-doped manganese oxide supercapacitor electrode material can be obtained. Although this invention has low cost and simple preparation process, it is difficult to accurately control the uniformity of doping by ball milling, and it is difficult to effectively avoid the pollution of ball milling media during the ball milling process. Although the industrialization of the method is feasible, it is necessary to achieve element doping by ball milling. However, the efficiency of this method is also debatable. The present invention comes from this.

Contents of the invention

The purpose of the present invention is to provide a method for preparing an element-doped manganese dioxide electrode material for supercapacitors, which solves the problem of using carbon materials as electrode materials for supercapacitors in the prior art with small specific capacitance, using noble metal oxides as electrode materials for supercapacitors, which is expensive and expensive. Toxic and weak electronic conductivity by simply using MnO ₂ , existing methods for element doping modification of manganese dioxide are cumbersome and complicated, and require high control conditions.

In order to solve these problems in the prior art, the technical solution provided by the invention is:

A method for preparing an element-doped manganese dioxide electrode material for a supercapacitor, characterized in that the method comprises the following steps:

(1) Synthesize LiA _x Mn _2-x O ₄ powder material with spinel structure in a suitable way; wherein A is selected from Ti, Ni, Sn, Co, Zn, Al metal addition elements, and x is in the range of 0.01 to 0.25 within the range

(2) The LiA _x Mn _2-x O ₄ powder material obtained in step (1) is delithiated using a lithium ion stripping agent without destroying the precursor spinel configuration to obtain element substitution doped MnO for supercapacitors ₂ electrode material.

Preferably, the method for synthesizing LiA _x Mn _2-x O ₄ powder materials with spinel structure in the step (1) is selected from solid-phase molten salt reaction method, sol-gel method, co-precipitation method; wherein A is selected from Elements are added from Ti, Ni, Sn, Co, Zn, and Al metals, and x is in the range of 0.01 to 0.25.

Preferably, the solid phase molten salt reaction method to synthesize LiA _x Mn _2-x O ₄ powder material with spinel structure includes mixing manganese source material, lithium source material and additive element material at a temperature of 850-970°C Calcined for 24-48 hours and cooled to obtain a LiA _x Mn _2-x O ₄ powder material with a spinel structure; wherein A is selected from Ti, Ni, S n, Co, Zn, Al metal addition elements, and x is in In the range of 0.01 to 0.25.

Preferably, in the method, the manganese source material powder and the additive element material are mixed at an A/Mn molar ratio of 0.2-0.25; wherein A is selected from Ti, Ni, Sn, Co, Zn, and Al metal additive elements.

Preferably, in the method, the lithium ion removing agent is selected from hydrochloric acid, nitric acid and sulfuric acid.

Preferably, when sulfuric acid is used for the delithiation reaction, the delithiation method comprises suspending the obtained spinel structure LiA _x Mn _2-x O ₄ powder in pure water, adding sulfuric acid solution and keeping The temperature is not higher than 50°C, until the pH of the slurry reaches 0.5-2, continue to stir for 1 hour, filter the reacted slurry, wash with water until the eluate is neutral, and the filtrate is kept at a temperature not higher than 90°C Vacuum drying to obtain element substitution doped MnO ₂ electrode materials; wherein A is selected from Ti, Ni, Sn, Co, Zn, Al metal addition elements, and x is in the range of 0.01 to 0.25.

In the technical scheme of the present invention, the precursor spinel-type LiA _x Mn _2-x O ₄ powder with appropriate powder properties is synthesized by the production method applied to the positive electrode material of lithium ion battery, and the manganese dioxide on the lattice structure level is realized. The elements are evenly doped and the spinel structure of manganese dioxide is shaped, and then the precursors prepared by soaking and washing under the conditions of controlling acidity and temperature are used in the process of powder soaking, washing, filtering and drying commonly used in chemical production. The powder material is delithiated, filtered and dried to obtain _MnO2 powder uniformly doped with elements.

When the solid-phase molten salt reaction method is adopted, the technical solution of the present invention granulates the manganese source material, the lithium source material and the added element material after mixing, and then calcines with programmed temperature, including low-temperature pre-calcination and high-temperature calcination to form a LiA _x Mn _2-x O ₄ powder material with spinel structure; LiA _x Mn _2-x O ₄ powder material with spinel structure is crushed, delithiated, washed and dried to obtain the required element-doped MnO2 pink.

Its specific technological process can adopt following steps to carry out:

A: Synthesis of spinel LiA _x Mn _2-x O ₄ powder material

Process the electrolytic manganese dioxide powder into a powder with a particle size of about 20 microns, and then stir it with additional element materials such as Ni(OH) ₂ at a ratio of A/Mn molar ratio 0.2-0.25 and Li/Mn molar ratio 0.5 Thoroughly mix in the grinding mill, use a temperature-controlled muffle furnace to calcinate the mixture at 850-970°C for 24-48 hours, and cool to obtain LiA _x Mn _2-x O ₄ powder material with spinel structure .

B. Preparation of element substitution doped MnO ₂

Suspend the prepared spinel LiA _x Mn _2-x O ₄ powder in pure water, add sulfuric acid solution under stirring conditions and keep the temperature not higher than 50°C until the pH of the slurry reaches 0.5-2, continue stirring for 1 hours, the reacted slurry was suction filtered or filtered with a filter press to remove water and washed repeatedly until the eluate was neutral, and the filtrate was vacuum-dried at a temperature not higher than 90°C to obtain element-doped Miscellaneous MnO2 powder.

In the _MnO2 powder prepared by the method of the present invention, the Mn in the crystal lattice is partially replaced by doping elements, and the doping elements are evenly replaced, the method has a high degree of industrialization maturity, and is a very potential manganese oxide electrode material for supercapacitors. Preparation route.

Compared with the scheme in the prior art, the advantages of the present invention are:

Compared with the prior art, the present invention realizes the uniform replacement and doping of doping elements by synthesizing the precursor powder material—element with spinel structure to replace lithium manganate, and avoids the difficulty of doping control in the existing doping technology In addition, the process of synthesizing precursor powder materials in the present invention is relatively mature, and some processes have been successfully applied to industrial production, and the technical route is mature and reliable, which is more suitable for industrialization.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment:

Fig. 1 is the preparation process flowchart of element-doped manganese dioxide electrode material for supercapacitor of the present invention;

Fig. 2 is a cyclic voltammetry scanning curve of the element-doped manganese dioxide electrode material prepared in Example 1 of the present invention.

Fig. 3 is a constant current charge and discharge curve of the substituted-doped manganese oxide electrode material prepared in Example 2 of the present invention.

Detailed ways

The above solution will be further described below in conjunction with specific embodiments. It should be understood that these examples are used to illustrate the present invention and not to limit the scope of the present invention. The implementation conditions used in the examples can be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not indicated are usually the conditions in routine experiments.

Embodiment 1: Preparation of Ni element doped manganese dioxide electrode material

Stir and grind the electrolytic manganese dioxide powder with a particle size of about 20 microns and Ni(OH) ₂ at the ratio of Ni/Mn molar ratio 0.2 and Li/Mn molar ratio 0.5, and mix the mixture thoroughly with a temperature-controlled muffle furnace. Calcined at 850-970°C for 48 hours and cooled to obtain a LiNi _x Mn _2-x O ₄ powder material with a spinel structure. Suspend the prepared spinel LiNi _x Mn _2-x O ₄ powder in pure water, slowly add sulfuric acid solution under stirring conditions, control the temperature not higher than 50°C, until the pH of the slurry reaches 0.5-2, continue stirring After 1 hour, the reacted slurry was centrifuged and precipitated, the supernatant was poured off, suction filtered and washed repeatedly until the eluate was neutral, and the filtrate was vacuum-dried at a temperature not higher than 90°C to obtain nickel-doped MnO2 pink.

The prepared Ni-doped manganese dioxide electrode material was used as the positive electrode, the graphite electrode was used as the negative electrode, the Ag/AgCl electrode was used as the reference electrode, and 1MNa2SO4 was used as the electrolyte to form a three-electrode test system to test the electrochemical performance of the material. The cyclic voltammetry scanning speed is 10mv/s, and the scanning interval is 0.0-1.0V; the constant current charge and discharge current is 200ma/g, and the voltage interval is 0-1.0v. The Ni-doped manganese dioxide electrode has a specific capacitance of 168f/g after 500 cycles.

Preparation of Example 2Ti element doped manganese dioxide electrode material

As described in Example 1, with 1250 orders below the anatase type TiO powder is prepared to obtain titanium-doped manganese oxide electrode material;

The prepared Ti-doped manganese dioxide electrode material was used as the positive electrode, the graphite electrode was used as the negative electrode, the Ag/AgCl electrode was used as the reference electrode, and 1MNa2SO4 was used as the electrolyte to form a three-electrode test system to test the electrochemical performance of the material. Cyclic voltammetry scanning speed 10mv/s, scanning interval 0.0-1.0V; constant current charge and discharge current 200mA/g, voltage interval 0-1.0v. The Ti-doped manganese dioxide electrode has a specific capacitance of 163f/g after 500 cycles.

The preparation of embodiment 3Co element doping manganese dioxide electrode material

As described in Example 1, cobalt-doped manganese oxide electrode material is prepared with Co2O3 powder below 1250 orders;

The prepared Co-doped manganese dioxide electrode material was used as the positive electrode, the graphite electrode was used as the negative electrode, the Ag/AgCl electrode was used as the reference electrode, and 1MNa2SO4 was used as the electrolyte to form a three-electrode test system to test the electrochemical performance of the material. Cyclic voltammetry scanning speed 10mv/s, scanning interval 0.0-1.0V; constant current charge and discharge current 200mA/g, voltage interval 0-1.0v. Co-doped manganese dioxide electrode has a specific capacitance of 178f/g after 500 cycles.

The above examples are only to illustrate the technical conception and characteristics of the present invention, and its purpose is to allow people familiar with this technology to understand the content of the present invention and implement it accordingly, and cannot limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (6)

1. the preparation method of an element-doping manganese bioxide electrode material for super capacitor is characterized in that said method comprising the steps of:

(1) with the synthetic LiA of suitable method with spinel structure _xMn _2-xO ₄Powder body material; Wherein A is selected from Ti, Ni, Sn, Co, Zn, Al metal interpolation element, and x is in 0.01～0.25 scope;

(2) LiA that (1) step is obtained _xMn _2-xO ₄Powder body material uses lithium ion to deviate from agent under the condition of not destroying presoma spinelle configuration to take off lithium and obtain ultracapacitor with element substitute doping MnO ₂Electrode material.

2. method according to claim 1 is characterized in that the synthetic LiA with spinel structure of described step (1) _xMn _2-xO ₄The method of powder body material is selected from solid phase molten-salt reaction method, sol-gal process, coprecipitation; Wherein A is selected from Ti, Ni, Sn, Co, Zn, Al metal interpolation element, and x is in 0.01～0.25 scope.

3. method according to claim 2 is characterized in that the LiA of described solid phase molten-salt reaction method synthetic spinel structure _xMn _2-xO ₄Powder body material comprises with manganese source material, lithium source material and adds the mixed back of element material and calcined 24-48 hour down at temperature 850-970 ℃ that cooling makes the LiA with spinel structure _xMn _2-xO ₄Powder body material; Wherein A is selected from Ti, Ni, Sn, Co, Zn, Al metal interpolation element, and x is in 0.01～0.25 scope.

4. method according to claim 3 is characterized in that manganese source material in the described method is that the ratio of 0.2-0.25 is mixed with adding element material in the A/Mn mol ratio; Wherein A is selected from Ti, Ni, Sn, Co, Zn, Al metal interpolation element.

5. method according to claim 1 is characterized in that lithium ion is deviate from agent in the described method to be selected from hydrochloric acid, nitric acid and sulfuric acid.

6. method according to claim 1 is characterized in that when adopting sulfuric acid to take off the lithium reaction, the described lithium method of taking off comprises the spinel structure LiA that will obtain _xMn _2-xO ₄Powder is suspended in the pure water, under stirring condition, add sulfuric acid solution and keep temperature not to be higher than 50 ℃, pH reaches 0.5-2 until slurry, continue to stir 1 hour, with reacted dope filtration, be washed to eluate and be neutral, vacuumize obtains element substitute doping MnO under 90 ℃ the temperature conditions not being higher than to leach thing ₂Electrode material; Wherein A is selected from Ti, Ni, Sn, Co, Zn, Al metal interpolation element, and x is in 0.01～0.25 scope.

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