WO2016134765A1

WO2016134765A1 - Electrode material for lithium-ion batteries and preparation method thereof

Info

Publication number: WO2016134765A1
Application number: PCT/EP2015/054011
Authority: WO
Inventors: Xin He; Jie Li; Jun Wang
Original assignee: Westfälische Wilhelms-Universität Münster
Priority date: 2015-02-26
Filing date: 2015-02-26
Publication date: 2016-09-01

Abstract

The present invention relates to a method of preparing a mesoporous metal oxide, comprising the steps of: a) providing metal salt; b) providing a template; c) mixing the metal salt of step a) with the template of step b) in a solvent to form a precursor solution and heating the precursor solution to obtain a precipitate; and d) calcining the precipitate obtained from step c) to form the mesoporous metal oxide, wherein the template is N-C_10-26 acyl-glutamic acid. The present invention further relates to a mesoporous metal oxide prepared by the method, and to a use of the mesoporous metal oxide as electrode material for electrochemical energy storage devices such as lithium-ion batteries.

Description

Electrode material for lithium-ion batteries and preparation method thereof

The present invention relates to the technical field of lithium ion batteries, and particularly relates to an electrode material for lithium-ion batteries, and a method for preparing the electrode material. Due to the demand of the fast-growing market of portable electronic devices and hybrid electric vehicles (HEVs), energy storage devices had a fast development in the past 20 years. Lithium ion batteries with high efficiency and high energy storage ability, have led battery technology for more than ten years. Super capacitors or electrochemical capacitors, which have several exciting properties like pulse supply of high power, a long cycle life and a high rate of charge propagation, also attract more and more research attention. The requirement of achieving better performance not only of lithium ion batteries and capacitors but also of other energy storage devices, put a focus on increasing their energy density and power.

Both cathode and anode active materials play important roles concerning the improvement of the energy density of energy storage devices. Particularly materials with a higher specific capacity are in demand. Nanostructured transition metal oxides currently are considered as the most promising candidates to replace the state of art anode materials such as graphite having a theoretical capacity of 372 mAh g^"1 in energy storage devices. A most interesting material, transition metal oxide Mn₂0₃ shows the advantage of environmentally benefit, in addition to its high theoretical capacity of 1018 mAh g^"1. This has aroused increasing attention on this material, especially on the electrochemical performance. However, Mn₂0₃ still faces the obstacle of a limited life due to volume expansion and particle agglomeration during cycling.

It is generally believed that the specific morphology of the metal oxide is one of the important factors that affect the electrochemical performance. Up to now, various metal oxides with different morphologies have been prepared. PCT application WO 2010/046629 Al for example discloses mesoporous lithium transition metal oxides which are prepared by a template method using surfactants as template, which finally are removed as organic composite by post calcination. Mesoporous structured metal oxide has larger surface area compared to other nanostructures providing more electrode/electrolyte interface to benefit the lithium ions intercalation/deintercalation reactions and the transfer of electrons. As a result, the specific capacity and cycling performance of electrode material could be improved.

Hence, further synthesis strategies for the fabrication of specific structures employing templates as structure-directing agent are developed, such as an ionic liquid-assisted solvothermal synthesis of Mn₂0₃ particles. However, the metal oxides still face several challenges, besides a still low surface area especially a low capacity retention and rate capability of electrodes during cycling.

There is an ongoing demand for improvements in the preparation of electrode materials for application in electrochemical energy storage systems.

Therefore, the object underlying the present invention was to provide a method for the manufacture of a metal oxide usable as electrode material in lithium ion batteries. The problem is solved by a method for preparing a mesoporous metal oxide, comprising the following steps:

a) providing a metal salt;

b) providing a template; c) mixing the metal salt of step a) with the template of step b) in a solvent to form a precursor solution and heating the precursor solution to obtain a precipitate; and

d) calcining the precipitate obtained from step c) to form the mesoporous metal oxide, wherein the template is N-Cio-26 acyl-glutamic acid.

It has been surprisingly found that the method provides the formation of a mesoporous metal oxide comprising primary hollow particles and a secondary mesoporous structure. The mesoporous metal oxide comprises primary hollow particles instead of solid ones as of known mesoporous metal oxide. Therefore, the electrode material provides a much enlarged surface area, which displays much better electrochemical performance. It is assumed that the formation of primary hollow particles rather than solid particles is due to a reaction mechanism based on N-Cio-26 acyl-glutamic acid as template.

The term "mesoporous" refers to a porous material containing pores with an average pore size in the range from about 1 nm to 50 nm. Porous materials having a pore size less than 1 nm are denoted microporous, and porous materials having a pore size in the range from 50 nm to 100 nm generally are denoted nanoporous. However, the definition is to be interpreted as a general classification of the material. The term "average" pore size refers to the average value of all pore sizes or arithmetically averaged pore size relative to all pores of the respective material. The pore size can for example be evaluated by using field-emission scanning electron microscopy. The mesoporous materials produced by the method of the invention hence may have pores larger than 50 nm and pores smaller than 1 nm.

The term "precipitate" as used herein refers to a solid formed in a solution during a chemical reaction. Precipitation occurs if the concentration of a compound exceeds its solubility for example when changing the temperature of the solution. The term "calcination" as used herein refers to the heating of a material in the presence of oxygen such as in air to create a condition of thermal decomposition. Calcining for example converts a metal hydroxide or a metal-lipid precursor to a respective metal oxide. The term "N-acyl-glutamic acid" as used herein refers to glutamic acid in which a hydrogen attached to the nitrogen has been replaced by an acyl group. The acyl group of the N-C 10-26 acyl-glutamic acid may have 10 to 26 carbon atoms. N-C₁₈ acyl-D-glutamic acid for example also is denoted N-(l-oxooctadecyl)-D-glutamic acid. The method advantageously provides for primary hollow particles having a secondary mesoporous structure. It is assumed that the effect of N-Cio-₂₆acyl glutamic acid on the morphology of the resulting structure of the metal oxide may be attributed to the influence of the chiral carbon of N-Cio-₂₆acyl-L-glutamic acid or N-Cio-₂₆acyl-D-glutamic acid, respectively, and on the effect of the chain length of the acyl group. It is assumed that the N- Cio-₂₆acyl-L/D glutamic acid coordinates the metal ion and upon heating forms a metal-lipid fiber precursor. It is further assumed that the effect of the template can be attributed to the interaction between the carboxylic head groups of the N-C 10-26 acyl-L/D glutamic acid and the highly reactive metal hydroxide species formed from metal salts by hydrolysis in aqueous solution. It was found that an increase in the concentration of the organic template and a control of the continuous/homogeneous nucleation and growth for example by time and/or temperature and also the use of inert atmosphere can influence the interactions with carboxylic acids.

It is assumed that the template method according to the invention is able to transcribe the helical structure of lipid fibers onto the microscopic helical assembly of inorganic metal ions. The interactions between lipid helical fibers through the metal-carboxylic acid (M-COOH) coordination at the interface are thought to result in the formation of carboxylic acid-metal ion coordinate helical fibers. The helical ribbons or fibers with a bilayer molecular arrangement can form by self-organization. The formation of the mesoporous metal oxide comprising primary hollow particles rather than primary solid particles is assumed to be attributed to this special reaction mechanism. Based on a different number of carbon atoms, the solubility and hydrolysis of templates are different. Further, the ability to coordinate metal ions and form a metal-lipid fiber and the length is also different. When heated to high temperature to remove the organic compounds, this results in a distinct size of left void space of the resulting metal oxide.

In embodiments, the N-Cio-26 acyl-glutamic acid is selected from the group of N-Cio-26 acyl- D-glutamic acid, N-Cio-26 acyl-L-glutamic acid, or mixtures thereof. The N-Cio-26 acyl- glutamic acid may be a mixture of N-acyl-L/D-glutamic acid (C_n-L/D-Glu) or may be used as pure chiral N-acyl-L-glutamic acid or N-acyl -D-glutamic acid. Advantageously, the chiral carbon of N-acyl-L-glutamic acid or N-acyl-D-glutamic acid can provide for differences in the morphology of the resulting metal oxide. A particularly advantageous difference was found in the pores size, which is attributed to the ability of the template to form metal-lipid fibers. Using N-Cigacyl-L-glutamic acid resulted in mesoporous metal oxide showing a larger average pore size compared to the use of N-Cigacyl-D-glutamic acid. Advantageously, different templates can lead to differences in the size of pore structure which have an effect on the electrochemical performance of the resulting metal oxide.

The template needs to be capable of forming a helical structure which may be transcribed onto the microscopic helical assembly of inorganic metal ions. The acyl group or the respective hydrolysed carboxylic acid hence has a chain length of at least 10 carbon atoms. Medium- chain or long-chain fatty acids are preferred. In embodiments, the acyl group of the N-acyl- glutamic acid has a chain length of > 12 to < 24 carbon atoms, preferably of > 13 to < 21 carbon atoms. Preferably the acyl group comprises a saturated carbon chain. Advantageously, saturated carbon chains are straight chains thus allowing for organized helical assembly. Preferred acyl groups are C₁₂, C₁₄, C₁₆, C₁₈ or C₂o acyl groups. In preferred embodiments, the acyl group is an octadecyl group.

The metal oxides manufactured by the method have been characterised by X-ray diffraction (XRD) analysis to possess a crystalline structure. The Brunauer-Emmett-Teller (BET) surface area of the manufactured manganese oxide further was determined using nitrogen adsorption

2 -1 2 -1 to exceed at least 30 m g^" and to be able to achieve a surface area of more than 70 m g^" .

The method is usable for the manufacture of mesoporous metal oxides of the formula M_xO_y wherein 1 < x < 3 and 1 < y < 5. In preferred embodiments of the method the metal of the metal salt is selected from the group consisting of Al, Mg, Mn, Ni, Co, Cr, B, Ca, Zr, Nb, Mo, Sr, Sb, W, V, Ge, Sn, Fe, Cu, Zn, and Ti or is a mixture of two or three of these metals. The metal M preferably is a transition metal. In preferred embodiments the metal is selected from the group consisting of Mn, Zn and Ti. Particularly by synthesizing Mn₂0₃ a transition metal oxide with a high theoretical capacity for use as anode material for lithium-ion batteries can be provided.

The metal is provided in step a) in form of a metal salt. The term "salt" as used herein refers to a metal compound wherein the metal is provided in cationic form together with an anionic counter compound. The metal salt may be an anorganic metal salt or an organic salt metal salt. In preferred embodiments, the metal salt is selected from the group consisting of a metal sulphate, acetate, carbonate, nitrate, chloride, oxalate, and mixtures thereof. The metal salt further may be an organically modified metal source particularly an organic metal salt. In further embodiments, the metal salt may be a metal acetylacetonate or a metal diisopropoxide bis(acetylacetonate), such as titanium diisopropoxide bis(acetylacetonate).

In embodiments of the method, the metal salt in step a) may be provided in the form of a solution of the metal salt in a solvent. The solution preferably is an aqueous solution. An aqueous solution advantageously supports the formation of metal hydroxides. The solvent hence preferably is water. In alternative embodiments, the metal salt may not be provided in solution, but may be dissolved in a solution of the template. In embodiments of the method, in step b) the template is provided in a solvent. The N-Cio-₂₆ acyl-glutamic acid may be mixed with a solvent or solved in a solvent to obtain a solution or dispersion of the N-acyl-glutamic acid. Preferably, N-Cio-₂₆acyl-L/D-glutamic acid initially is solved in alcohol and afterwards a mixture of water and alcohols is added. Advantageously, this provides that the template will stay in solution even after mixing with water. The alcohol preferably is selected from the group consisting of methanol, ethanol, glycol, acetone and mixtures thereof. N-C 10-26 acyl-glutamic was found to solve best in these alcohols. Preferred alcohols are methanol and ethanol. N-C 10-26 acyl-glutamic may be solved in ethanol and to this solution may be added a mixture of water and ethanol. The solvent in step b) and hence also in step c) preferably is a mixture of water and alcohol. An aqueous solution

advantageously supports the hydrolysis of the N-C 10-26 acyl-glutamic acid into a C 10-26 carboxylic acid and glutamic acid.

In embodiments of the method, particularly in laboratory scale embodiments, the mole ratio of the alcohol to the N-C 10-26 acyl-glutamic acid may be in a range from > 2xl0³ to < 1.2xl0⁴,

3 3 3 preferably in a range from > 4x10 to < 8x10 , more preferably in a range from > 5.5x10 to < 7x10 . In further embodiments, the mole ratio of the alcohol to the N-C 10-26 acyl-glutamic acid

-2 2 -5 -2 may be in a range of > 10^" mol to < 10 mol alcohol to > 10^" to < 10^" mol N-Cio-26 acyl-

-5 -3 glutamic acid, preferably in a range of > 0.1 mol to < 20 mol alcohol to 5x10^" mol to < 6x10^" mol N-Cio-26 acyl-glutamic acid, more preferably in a range of > 1 to < 5 mol alcohol to 2x10^" ⁴ mol to < 8xl0^"4 mol N-C 10-26 acyl-glutamic acid. In an embodiment, the mole ratio of the alcohol to the N-Cio-26 acyl-glutamic acid in may be 2.2 mol alcohol to 4xl0^"4 mol N-Cio-26 acyl-glutamic acid. For example, 4xl0^"4 mol of N-C₁₈- acyl-glutamic acid may be solved in 40 ml, corresponding to 1.1 mol, of ethanol and afterwards a solution of 40 ml ethanol and 400 ml water may be added.

Mixing of the metal salt and N-Cio-26 acyl-glutamic acid with the respective solvent in steps a) and b) and/or the mixing of the metal salt and N-C 10-26 acyl-glutamic acid in step c) may include agitating the solution to form a solution, a dispersion or an emulsion. Solubility of the N-C 10-26 acyl-glutamic acid is influenced by the chain length of the acyl group. A solution may be formed or a dispersion. As used herein the term solution includes also a dispersion. Preferably the mixing may be supported by stirring.

Further, the mixing may be supported by heating the solution. Particularly mixing the N-C ₁₀-26 acyl-glutamic acid with an aqueous solvent may be performed under heating. The aqueous solution of N-C ₁₀-26 acyl-glutamic acid may be heated to a temperature in a range of > 40 °C to < 80 °C, preferably in a range of > 45 °C to < 70 °C, more preferably to temperatures in the range of > 50 °C to < 60 °C.

The metal salt and the template N-Cio-26 acyl-glutamic acid are mixed to form a precursor solution, and the precursor solution is heated. Mixing and heating may be performed consecutively. Preferably, mixing and heating are performed in parallel. A solution of N-C₁₀- 26 acyl-glutamic acid may be heated in step b) and after adding a solution of the metal salt heating of the precursor solution may continue at the same or a different temperature.

Particularly the step c) of the method provides for a mechanism that allows to control the interaction between the carboxylic head groups and highly reactive M-OH species formed by hydrolysis of the metal (M) salt in an aqueous solvent. It was found that an increase in the concentration of the organic template and a control of the continuous/homogeneous nucleation and growth could lead to fine interactions of the metal ions with the C ₁₀-26 carboxylic acid formed by hydrolysis of the N-C 10-26 acyl-glutamic acid. In preferred embodiments, particularly in laboratory scale embodiments, the mole ratio of the

-4 -2 metal salt to the template in the precursor solution of step c) is in a range of > 10^" to < 5x10^"

-5 -2

mol metal salt to > 10^" to < 10^" mol template. The term "mole ratio" or "molar ratio" as used herein refers to the ratio between the amounts in moles of any two compounds involved in a chemical reaction. It was found that if the amount of the metal salt is higher, a large solid particle or a lot of small particles which strongly agglomerate will form, or only a small part of the particles with have pores on the surface. If the amount of the metal salt however is too low, the reaction will waste template which reduces the benefit of the method. Preferably, the mole ratio of the metal salt to the template in the precursor solution is in a range from > 5x 10^" ⁴ to < 10^"2 mol metal salt to > 5xl0^"5 to < 6xl0^"3 mol template, more preferably in a range

-3 -3 -5 -3

from > lx 10^" to < 5x10^" mol metal salt to > 5x10^" to < 6x10^" mol template. Such ranges of the mole ratio of the metal salt to N-C 10-26 acyl-glutamic acid in the precursor solution have been shown to provide for mesoporous metal oxides with desired structure. In an

embodiment, the mole ratio of the metal salt to the template in the precursor solution may be 1.5xl0^"3 mol metal salt to 4xl0^"4 mol N-Cio-26 acyl-glutamic acid.

The precursor solution is heated to obtain a precipitate. In preferred embodiments, the precursor solution is heated to a temperature in a range of > 40 °C to < 80 °C. It has been found that temperatures below 80 °C are particularly suitable for the formation of a precursor with the desired structure. Higher temperatures may increase alcohol evaporation and reduce the stability of coordinate bonds. Preferably the precursor solution is heated to a temperature in a range of > 45 °C to < 70 °C, more preferably to temperatures in the range of > 50 °C to < 60 °C. Particularly temperatures in the range of 50 °C, 55 °C or 60 °C have been found to support the interaction between the carboxylic head groups and the metal hydroxide species and provide for a continuous nucleation and growth to form a homogeneous precursor. The heating may be in air or in another gaseous atmosphere such as under nitrogen or argon. The atmosphere will influence the crystal particle grow. It was found that by heating under argon particles having a smaller size could be obtained. According to the reaction temperature the precursor solution may be allowed to react for shorter or longer periods. In preferred embodiments, the precursor solution is reacted for a time period in a range of > 10 minutes to < 10 hours, preferably in the range of > 1 hour to < 5 hours, more preferably in the range of > 2 hours to < 4 hours. Such time ranges have been shown to provide for a good precursor formation.

The obtained precipitate may be separated from the solution for example by filtering. The precipitate further may be washed from residues such as by rinsing with water. After filtering the precipitate optionally may be dried before calcining. Preferably, drying may be in a temperature range from under -120 °C to 100 °C. Freeze-drying is preferred. The drying time may lie in a range from 30 minutes to 168 hours.

In the step d) the precipitate obtained from step c) is calcined to form the mesoporous metal oxide. The calcination converts the material to the desired crystal phase. Further, the calcination removes organic residuals. The surfactant removal and the calcining thus are combined, such that the surfactant is removed by thermal decomposition at a temperature suitable for calcining. Temperatures in a range from > 300 °C to < 1000 °C may be used to convert the respective metal-lipid precursor to the desired crystal phase of a metal oxide. A suitable temperature may be selected in accordance with the desired metal oxide. For the synthesis of Mn₂0₃, the calcining temperature preferably lies in a range from > 450 °C to < 650 °C and more preferably in the range from > 500 °C to < 600 °C. For the synthesis of ZnO and Ti0₂, respectively, the calcining temperature preferably lies in the range from > 500 °C to < 600 °C, more preferably at about 550 °C. Calcining at temperatures as low as possible may have the advantage that pore integrity will be maintained and porous structure in general suffers less damage.

The time range for calcining may lie in a range from > 1 hour to < 10 hours, preferably in a range from > 3 hour to < 5 hours. It was found that longer calcining time lead to a growth of larger particles. Shorter calcining times might cause that the template can not be fully removed and that the resulting oxide may partly keep some organics. The time until the furnace reaches the calcining time also may be varied. The heating rate may lie in a range from 0.5 °C /min to 20 °C /min, preferably a range from 1 °C /min to 5 °C /min. It was found that a slower heating rate to reach the calcination temperature advantageously resulted in smaller particles. Smaller particles provide large surface area and hence better performance as electrode material. It is assumed that by slow heating the carbon template slowly transformed before the carbon was removed by the calcination while at the same time the Mn₂0₃ particles are formed.

Another aspect refers to a mesoporous metal oxide of the formula M_xO_y wherein 1 < x < 3 and 1 < y < 5, and wherein the metal M is selected from the group consisting of Al, Mg, Mn, Ni, Co, Cr, B, Ca, Zr, Nb, Mo, Sr, Sb, W, V, Ge, Sn, Fe, Cu, Zn, and Ti or is an alloy of two or three of these metals prepared by the method according to the invention. The metal M preferably is a transition metal. In preferred embodiments the metal is selected from the group consisting of Mn, Zn and Ti. In a preferred embodiment, the mesoporous metal oxide is Mn₂0₃. The metal oxide prepared by the method particularly is usable as active material for electrodes used in lithium-ion batteries, lithium-ion capacitors and supercapacitors.

Particularly Mn₂0₃ provides a mesoporous transition metal oxide with a high theoretical capacity for use as anode material for lithium-ion batteries. In a further embodiment, the mesoporous metal oxide is Ti0₂. In a further embodiment, the mesoporous metal oxide is ZnO. The mesoporous metal oxide can provide for primary hollow particles having a secondary mesoporous structure. It was found that these metal oxides provide a remarkably large surface area. In embodiments, the mesoporous metal oxide has a BET surface area in a range from >

2 -1 2 -1 2 -1 2 -1

20 m g^" to < 80 m g^" , preferably in a range from > 30 m g^" to < 75 m g^" , more preferably in a range from > 35 m 2 g-^"1 to < 73 m 2 g-^"1. The Brunauer-Emmett-Teller (BET) surface area of the metal oxide was determined using nitrogen adsorption. A BET surface area of the mesoporous metal oxide exceeding 30 m 2 g-^"1 and even achieving more than 70 m 2 g-^"1 could be determined. In embodiments, the mesoporous metal oxide has a desorption average pore width in a range from > 1 nm to < 50 nm, preferably in a range from > 5 nm to < 40 nm, more preferably in a range from > 7 nm to < 36 nm. The desorption average pore width was determined using the BET results. Advantageously, a high porosity and a large pore size can help to stabilize the structure of the active material during charge/discharge processes. The insertion of lithium generates stress in the material matrix, and the strain induced by stress not only deforms the structure by expansion but also compromises the lithium diffusion. The maximum stress around the pore increases if the initial pore size is decreased, which would act as a source of fracture. Generally speaking, decreasing the initial pore radius / pore-to-pore distance ratio (r/1 ratio) to a lower value, i.e. low porosity, would increase the maximum stress, and a smaller initial pore would result in higher maximum stress around the pore.

Another aspect refers to an electrode material for electrochemical energy storage devices particularly for lithium and lithium-ion batteries prepared by the method according to the invention. The electrode material is a mesoporous metal oxide of the formula M_xO_y wherein 1 < x < 3 and 1 < y < 5, and wherein the metal M is selected from the group consisting of Al, Mg, Mn, Ni, Co, Cr, B, Ca, Zr, Nb, Mo, Sr, Sb, W, V, Ge, Sn, Fe, Cu, Zn, and Ti or is an alloy of two or three of these metals. The electrode material obtained by the method may have

2 -1 2 -1

a BET surface area in a range from > 20 m g^" to < 80 m g^" , preferably in a range from > 30 m 2 g-^"1 to < 75 m 2 g-^"1 , more preferably in a range from > 35 m 2 g-^"1 to < 73 m 2 g-^"1. Further, the mesoporous metal oxide obtained by the method may have a desorption average pore width in a range from > 1 nm to < 50 nm, preferably in a range from > 5 nm to < 40 nm, more preferably in a range from > 7 nm to < 36 nm. The electrode material preferable may be Mn₂0₃, Ti0₂ or ZnO. It was found that the electrode material manufactured by the method according to the invention provides improved high rate performance and cycling stability of the resulting electrodes.

Another aspect of the invention refers to an electrode comprising as electrode material a mesoporous metal oxide prepared by the method according to the invention. The electrode can particularly be an electrode for lithium-ion batteries, lithium-ion capacitors and supercapacitors. Surprisingly, it was found that electrodes manufactured from metal oxide prepared by the method showed an exceptional high rate performance. This allows the realisation of lithium-ion batteries, lithium-ion capacitors and supercapacitors based on cost- effective and environmentally friendly manganese oxide which is considered an essential aspect of the invention.

Electrode material with a primary hollow and secondary mesoporous structure achieved markedly improved electrochemical performance in view of specific capacity and cycling stability when being used as anode material for energy storage devices. Mn₂0₃ as a good example, showed a charge capacity around 1150 mAh g^"1 under 0.1C, which is 350 mAh g^"1 higher than the best performance of 800 mAh g^"1 for Mn₂0₃ as known. This provides the possibility of a successful commercialization of these materials in order to enable lithium-ion batteries, sodium-ion batteries and super capacitors technology to take a step forward in terms of energy and power density.

Another aspect of the invention refers to an electrochemical energy storage device, comprising an electrode comprising a mesoporous metal oxide prepared by the method according to the invention as electrode material. The electrochemical energy storage device particularly is a lithium-ion battery, a lithium-ion capacitor or a super capacitor. A lithium-ion battery for example can comprise an anode manufactured from active material prepared by the method as described, a cathodic electrode, and an electrolyte.

Another aspect of the invention refers to the use of a mesoporous metal oxide prepared by the method according to the invention as electrode material for electrochemical energy storage devices, particularly as active material for electrodes used in lithium-ion batteries, lithium-ion capacitors and super capacitors.

Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The examples which follow serve to illustrate the invention in more detail but do not constitute a limitation thereof.

In the figures show:

Figure 1 shows a scan electron microscope (SEM) photograph of the precipitated

Mn(Ci₈H₃₅0₂)₂ precursor obtained after step c) of example 4 under 20k magnification.

Figure 2 shows a SEM photograph of the calcined mesoporous Mn₂0₃ obtained after step d) according to example 4 under 50k magnification.

Figure 3 shows a SEM photograph of the calcined mesoporous Mn₂0₃ obtained after step d) according to example 4 under 20k magnification.

Figure 4 shows a powder X-ray diffraction (XRD) pattern of the calcined mesoporous

Mn₂0₃ obtained according to example 4 (sample 1). Figure 5 shows a SEM photograph of the calcined mesoporous Mn₂0₃ obtained after step d) according to example 5 under 50k magnification.

Figure 6 shows a SEM photograph of the calcined mesoporous Mn₂0₃ obtained after step d) according to example 5 under 10k magnification.

Figure 7 shows a powder X-ray diffraction (XRD) pattern of the calcined mesoporous

Mn₂0₃ obtained according to example 5 (sample 2).

Figure 8 shows a SEM photograph of the calcined mesoporous Mn₂0₃ obtained after step d) according to example 6 under 50k magnification.

Figure 9 shows a SEM photograph of the calcined mesoporous Mn₂0₃ obtained after step d) according to example 6 under 10k magnification.

Figure 10 shows a powder X-ray diffraction (XRD) pattern of the calcined mesoporous

Mn₂0₃ obtained according to example 6 (sample 3).

Figure 11 shows a SEM photograph of the calcined mesoporous Mn₂0₃ obtained after step d) according to example 7 under 100k magnification.

Figure 12 shows a powder X-ray diffraction (XRD) pattern of the calcined mesoporous

Mn₂0₃ obtained according to example 7.

Figure 13 shows a SEM photograph of mesoporous ZnO obtained after step d) according to example 8 under 10k magnification.

Figure 14 shows a SEM photograph of mesoporous Ti0₂ obtained after step d) according to example 9 under 20k magnification.

Figure 15 shows the first cycle performance of discharge and charge capacity of the

mesoporous Mn₂0₃ of example 4.

Figure 16 shows the rate performance of the mesoporous Mn₂0₃ of example 4. Given is the charge and discharge capacity for 300 cycles.

Example 1

Preparation of N-(l-oxooctadecyl)-D-glutamic acid (Ci₈-D-Glu) 0.1 mol stearoyl chloride (Sigma Aldrich) and 0.1 mol sodium hydroxide (Sigma Aldrich) were solved in 20 ml deionized water. 0.12 mol D-glutamic acid (Sigma Aldrich) was solved in a solvent mixture of 70 ml of deionized water and 60 ml acetone, then 0.24 mol sodium hydroxide was added into the solution to reach a pH of 12. The solution was stirred at 30 °C for 20 minutes. Afterwards, the stearoyl chloride solution was added to the L-glutamic acid solution, and during this procedure the reaction system was kept at a pH of 12. After stirring for one hour, the solvent was cooled down to room temperature (22±2°C) and acidified to pH 1 with HC1. A white precipitated formed. The precipitated solid N-C₁₈ acyl-D-glutamic acid was washed in pentane ether and dried at 40 °C to obtain pure crystals.

Example 2

Preparation of N-(l-oxooctadecyl)-L-glutamic acid (Cig-L-Glu)

The synthesis was performed as described under example 1 with the exception that 0.12 mol L-glutamic acid (Sigma Aldrich) were used.

Example 3

Preparation of N-(l-oxotridecyl)-D-glutamic acid (Co-D-Glu)

The synthesis was performed as described under example 1 with the exception that 0.1 mol tridecanoyl chloride (Sigma Aldrich) was used.

Example 4

Preparation of Mn₂0₃

Step a) Preparation of a manganese solution

0.26 g of manganese acetate Mn(ac)₂ (Sigma Aldrich) were solved in 50 ml of deionized water under stirring for 10 minutes.

Step b) Preparation of a template solution of N-(l-oxooctadecyl)-D-glutamic acid 0.16 g of N-(l-oxooctadecyl)-D-glutamic acid (Cig-D-Glu) obtained from example 1 were solved in 40 ml of ethanol under stirring for 10 minutes. To the solution of Ci₈-D-Glu in ethanol a solvent mixture of 400 ml deionized water and 40 ml ethanol was added and the mixture was then heated up to 55 °C under stirring for 2 hours. The template solution appeared like a clear gel. The molar ratio of N-(l-oxooctadecyl)-D-glutamic acid (4x xlO^"4 mol) to ethanol (2.2 mol) was 1 to 5.5x10 .

Step c) Preparation of the precursor

The aqueous manganese solution of step a) was added to the solution of the template of step b) at a temperature of 55°C under stirring. The molar ratio of Mn(ac)₂ to N-(l-oxooctadecyl)- D-glutamic acid was 1.5xl0^"3 to 4xl0^"4 mol. The resulting precursor solution was kept at 55 °C under stirring for 4 hours. After 10 minutes the formation of a precipitate was observed, which after one hour turned to a flocculent precipitate. After 4 hours the mixture was left to cool to room temperature and the precipitate was collected by filtration and washed thoroughly with deionized water. The precipitate was dispersed in 20 ml of deionized water and freeze dried at -105 °C for 72 h. The freeze dried precipitate was then used for evaluation of particle morphology.

Particle morphology was evaluated by using field-emission scanning electron microscopy (FE - SEM, Zeiss Auriga® microscope). Figure 1 shows the SEM photograph of the precipitate under 20k magnification. As can be seen in Figure 1, the freeze dried precipitate showed a helical structure. It is assumed that interactions between the Ci₈-lipid helical fibers through the manganese-carboxylic acid coordination at the interface resulted in the formation of the shown precursor of Ci₈-lipid-metal hybrid helical fibers. Such helical ribbons or fibers with a bilayer molecular arrangement can form by self-organization in the precursor solution.

Step d) Calcination of the precursor 0.25 g of the precipitate obtained from step c) were transferred to a muffle furnace. The muffle furnace was sealed and the precipitate was calcined in air at 500 °C for 4 h. Afterwards the furnace was cooled to room temperature. The as prepared manganese oxide powder was briefly for about 30 seconds mortared by hand.

The manganese oxide powder was subjected to SEM and XRD characterization and surface area measurements by BET for characterisation of the obtained material. The crystal structure of the prepared oxide was characterized by X-ray diffraction (XRD) in the 2Θ range of 10-90 ° at a scan rate of 0.0196 °/step, which was performed on a Bruker D8 Advance (Germany) with Cu K_u radiation at room temperature. Particle morphology was again evaluated by using field-emission scanning electron microscopy (FE - SEM, Zeiss Auriga ).

Figure 2 and Figure 3 show the large-size mesoporous structure and primary hollow particle of the prepared Mn₂03. Figure 2 shows a large pore which had a hole size in the range from 300 nm to 800 nm and hence gives evidence for the primary hollowness of the particles. Figure 3 shows besides a large pore also the small pores characterizing the secondary mesoporous structure of the manganese oxide. It is assumed that the reaction time of 4 hours for the formation of the precursor allowed all or nearly all metal ions to form a metal-lipid fiber template. It is further assumed that the low calcination temperature of 500 °C limited particle growth. The desorption average pore width was calculated to 153.6A. The desorption average pore width was calculated on a Micrometrics ASAP 2020 (Accelerated Surface Area and Porosimetry Analyzer, Micromeritics) using the results of the BET specific surface area using nitrogen adsorption. The BET specific surface area of the manufactured manganese oxide was determined using nitrogen adsorption (Brunauer-Emmett-Teller method) using a Micrometrics ASAP 2020 (Accelerated Surface Area and Porosimetry Analyzer, Micromeritics) at liquid nitrogen temperature. The BET surface area for this sample was 52.7 m² g^"1. The crystal structure of the manganese oxide was confirmed by X-ray diffraction (XRD). As shown in Figure 4, the observed diffraction peaks in the corresponding XRD pattern could be clearly determined as belonging to orthorhombic Mn₂0₃ (JCPDS Card No. 24-0508) with space group of la - 3. This confirmed that Mn₂0₃ was obtained that possessed a crystalline structure.

Examples 5 to 7

Preparation of Mn₂0₃

The preparation of Mn₂0₃ was repeated using the procedure as generally described in example 4 above, wherein the precipitate after collection by filtration was not washed and characterized but directly dispersed in deionized water and freeze dried. The metal salts and templates obtained from examples 1 to 3 as shown in the table 1 and the experimental conditions as shown in the table 2 were used. Table 1 : metal salts and templates

Table 2: experimental conditions

The figure 5 and figure 6 show SEM photographs of the calcined mesoporous Mn₂0₃ obtained according to example 5 under 50k and 10 k magnification. As can be seen in the figures 5 and 6 the shorter length of the Ci₃-carbon chain resulted in a less pronounced formation of the inner hollow space of the particles, but still a void space in the Mn₂0₃ network existed. It is assumed that the finer network in which the single fibers appear to be more closely woven to each other compared to example 4, are to be attributed to the shorter carbon chain of the template and to the increase in the hydrolysis time. The BET surface area

2 -1

for the Mn₂0₃ of example 5 was determined to 35.9 m g^" and the desorption average pore width to 262.7 A. The XRD pattern of the calcined manganese oxide according to Figure 7 again confirmed the crystalline structure of orthorhombic Mn₂0₃.

The SEM photographs of the calcined mesoporous Mn₂0₃ obtained according to example 6 shown in figures 8 and 9 show a different morphology. As can be seen in the figures 8 and 9, the network structure is also quite clear. Compared to the Mn₂0₃ obtained from examples 4 and 7, the shown mesoporous structure shows the same hollow void space as example 4 and 7, wherein a difference was seen in the pore size, as the structure showed larger pores. The difference in the morphology is attributed to the use of the N-Ci8-L-glutamic acid instead of N-Ci8-D-glutamic acid.

Mn₂0₃ obtained from example 4 showed clear single particles, while the Mn₂0₃ obtained from example 6 showed small particles aggregate to form the structure. This effect is attributed to the higher calcination temperature compared to example 4. The BET surface area

2 -1

for the Mn₂0₃ of example 6 was determined to 33.31 m g^" , and the desorption average pore width to 405.7 A. The XRD pattern of the calcined Mn₂0₃ according to Figure 10 confirmed the crystalline structure of orthorhombic Mn₂0₃.

In example 7, heating of the precursor solution to obtain a precipitate in step c) was performed under argon atmosphere. The precursor further was more slowly heated by a heating rate of 2 °C /min compared to 10 °C /min as in examples 4 to 6 to reach the calcination temperature of 600 °C. The time needed for the increase in temperature was not included in the calcination time. The figure 11 shows an SEM photograph of the calcined mesoporous Mn₂03 obtained according to example 7 under 100 k magnification. The figure 11 shows particularly clear evidence of the primary hollow structure and of the secondary mesoporous structure of the Mn₂0₃. The Mn₂0₃ obtained from example 7 also showed small particles aggregate to form the structure, which is attributed to the higher calcination temperature compared to example 4 as also was seen in example 6. It is assumed that the slow heating to reach the calcination temperature slowly transformed the carbon template before the carbon was removed by the calcination. At the same time the Mn₂0₃ particles are formed. It is assumed that the slow heating rate and also the argon atmosphere when heating the precursor solution in step c) both

2 -1 limited the crystal grow. The BET surface area for example 7 was determined to 72.3 m g^" , and the desorption average pore width to 75.7 A. As the desorption average pore width is an average value, the result means that a majority of small pores of a size from 1 to 10 nm were formed. The XRD pattern of the calcined Mn₂0₃ according to Figure 12 confirmed the crystalline structure of orthorhombic Mn₂0₃.

The examples 5 to 7 show the preparation of hollow mesoporous Mn₂0₃ using different conditions for the formation of the metal-lipid fiber precursor and calcination conditions. It is assumed that the template method according to the invention transcribes the helical structure of lipid fibers onto the microscopic helical assembly of inorganic metal ions and that the formation of the mesoporous metal oxide comprising primary hollow particles rather than primary solid particles is due to this special reaction mechanism.

Example 8

Preparation of ZnO

0.19 g of Zn(N0₃)₂ (Sigma Aldrich) were solved in 50 ml deionized water under stirring. 0.16 g of N-(l-oxooctadecyl)-D-glutamic acid (Ci₈-D-Glu) obtained from example 1 were solved in 40 ml of ethanol under stirring for 10 minutes. To the solution of Ci₈-D-Glu in ethanol a solvent mixture of 400 ml deionized water and 40 ml ethanol was added and the mixture was then heated up to 55 °C under stirring for 2 hours. The template solution appeared like a clear gel. The molar ratio of N-(l-oxooctadecyl)-D-glutamic acid (4xl0^~4 mol) to ethanol (2.2 mol) was 1 to 5500. The zinc solution was then added to the solution of the template under stirring at a temperature of 60 °C. The molar ratio of Zn(N0₃)₂ to N-(l-oxooctadecyl)-D-glutamic acid was 10^"3 to 4xl0^"4 mol. The precursor solution was heated at 60 °C under stirring for 4 hours. After 30 minutes the formation of a precipitate was observed. After 4 hours the mixture was cooled to room temperature, then the precipitate was collected by filtration, dispersed in 20 ml deionized water and freeze dried. 0.22 g of the precipitate were transferred to a muffle furnace. The muffle furnace was sealed and the precipitate was calcined in air at 550 °C for 5 h. Afterwards the furnace was cooled to room temperature.

The zinc oxide powder was subjected to SEM characterization. Figure 13 shows the small- sized mesoporous structure comprised of primary hollow spherical particles of the prepared ZnO. The network structure ZnO showed several 40-100 nm hollow spherical particles with 5-10 nm pores splicing together.

Example 9

Preparation of hollow mesoporous Ti0₂

0.16 g of N-(l-oxooctadecyl)-D-glutamic acid (Ci₈-D-Glu) obtained from example 1 were solved in 40 ml of ethanol under stirring for 10 minutes. To the solution of Ci₈-D-Glu in ethanol a solvent mixture of 400 ml deionized water and 40 ml ethanol was added and the mixture was then heated up to 55 °C under stirring for 2 hours. The molar ratio of N-(l- oxooctadecyl)-D-glutamic acid (4xl0^~4 mol) to ethanol (2.2 mol) was 1 to 5.5xl0³. Then 2 ml of titanium diisopropoxide bis(acetylacetonate) 75 wt. % in isopropanol (Sigma Aldrich) were added drop-wise into the template solution in 10 minutes and then stirred at 60°C for 2 hours. The molar ratio of titanium diisopropoxide bis(acetylacetonate) to N-(l-oxooctadecyl)-D- glutamic acid was 4.1xl0^~3 mol to 4xl0^~4 mol. After 1 h the formation of a pale-yellow precipitate was observed. After 2 hours the mixture was cooled to room temperature and the precipitate was collected by filtration, dispersed in 20 ml deionized water and freeze dried. 0.17 g of the precipitate was transferred to a muffle furnace. The muffle furnace was sealed and the precipitate was calcined in air at 550 °C for 5 h. Afterwards the furnace was cooled to room temperature.

The titanium oxide powder was subjected to SEM characterization. Figure 14 shows the small-sized mesoporous structure comprised of primary hollow nano fibers of the prepared titanium oxide. As can be seen in the SEM photograph the secondary particle morphology of the prepared Ti0₂ had an ordered network structure and the oxide fibers had a spiral shape.

Comparative Example 10

Preparation of Mn₂0₃ using a ionic liquid-assisted hydrothermal synthesis

0.5 g Mn(ac)₂ and 7 ml l-Butyl-3-methylimidazolium trifluoromethanesulfonate (99.5%) as structure-directing agent were first dissolved in 54 ml deionized water under stirring for half an hour. The solution was then transferred into a Teflon-lined autoclave. The autoclave was sealed and heated at 160 °C for 3 hours. Afterwards, the autoclave was cooled to room temperature. The brown precipitate was collected by filtration and washed thoroughly with deionized water. The obtained MnF₂ precursor was dried at 80 °C for 12 hours. Mn₂0₃ was synthesized by a direct post heat treatment of the MnF₂ precursor in air at 600 °C for 5h in a muffle furnace.

The crystal structure of the prepared material was characterized by X-ray diffraction (XRD) in the 2Θ range of 10-90 ° at a scan rate of 0.0196 °/step on a Bruker D8 Advance (Germany) with Cu K_a radiation at room temperature. The XRD pattern confirmed that by the calcination, the tetragonal MnF₂ was transformed into orthorhombic Mn₂0₃. Further, the particle morphology was evaluated by using field-emission scanning electron microscopy (FE - SEM, Zeiss Auriga). The SEM image of the obtained Mn₂0₃ showed distributed particles without agglomeration, and a hollow structure of the crystals. Moreover, the polyhedron morphology of the MnF₂ precursor was maintained.

This example for comparison shows that using the ionic liquid-assisted hydrothermal method via a MnF₂ precursor with hollow polyhedron morphology and by further calcination a Mn₂0₃ material of hollow particles was synthesized. The Mn₂0₃ material was usable as anode material for lithium ion batteries.

Example 11

Electrochemical characterization Electrode preparation:

Anode electrodes were prepared by casting a slurry of Mn₂0₃ active material obtained of Example 4, Super C65 conductive agent and carboxymethyl cellulose (CMC) binder at a dry weight ratio of 70:20: 10, onto copper foil and drying overnight in a vacuum at 80 °C. The slurry was prepared by magnetic stirring for 12 h to maintain the hollow morphology of the active material. The mass loading values of the active material was about 1.5 mg cm^"2. The active material mass loading was determined by weighting the electrodes, in a dry room or a glove box at room temperature, then the weight was divided by the area of the coated copper foil. The electrodes were assembled into CR2032 coin cells with lithium metal as counter electrode and 1M LiPF₆ in 3:7 (by weight) ethylene carbonate (EC) : dimethyl carbonate (DEC) as electrolyte. Galvanostatic cycling measurements were carried out at 20°C on a Maccor series 4000 battery tester in a voltage range of 0.01-3.0 V (nominal current, 1 C = 1018 mA g^" ). Since lithium foil was used as counter and reference electrode, potential values given are referring to the Li /Li reference couple.

Figure 15 shows the first cycle performance of discharge and charge capacity of the Mn₂0₃ of example 4 as anode active material at 0.1C. As can be seen in the Figure 15, being used as anode material for lithium-ion battery, the mesoporous structured and hollow primary particle comprising Mn₂0₃ could deliver 1600 mAh g^"1 discharge capacity and 1150 mAh g^"1 charge capacity in the initial cycle (0.1C, 1C=1018 mAh g^"1). This capacity provides an increase of more than 300 mAh g^"1 compared the results of materials in grain or sphere shape prepared via state of the art synthesis approaches.

Figure 16 shows the rate performance of the Mn₂0₃ of example 4 over 300 charge and discharge cycles. As can be seen in the Figure 16, no fading for more than 300 cycles was observed for the Mn₂0₃ anode material when discharged/charged at 1 C. The capacity could maintain at least 700 mAh g^"1. The material thus showed a very good cycling stability.

Comparative Example 12

Electrochemical characterization of the Mn₂0₃ of Example 10 The electrochemical performance of the hollow Mn₂0₃ of Example 10 as anode material for lithium ion batteries was investigated for comparison. Anode electrodes were prepared by casting a slurry of the Mn₂0₃ active material for comparison, Super C65 conductive agent and carboxymethyl cellulose (CMC) binder at a dry weight ratio of 70:20: 10 and assembled into CR2032 coin cells as described under Example 11. Galvanostatic cycling measurements were carried out in a voltage range of 0.01-3.0 V (nominal current, 1 C = 1018 mA g^"1) as described under Example 11. The hollow Mn₂0₃ of example 10 delivered a discharge capacity of 1500 mAh g^"1 and a charge capacity 800 mAh g^"1 charge capacity in the initial cycle. The capacity hence is 150 mAh g^"1 and 300 mAh g^"1, respectively, lower compared the results of the Mn₂0₃ material prepared according to the method of the invention. The rate performance of the Mn₂0₃ of example 10 was measured over 150 charge and discharge cycles at a current density of 1018 mAh g^"1 and no obvious capacity fading was observed. However, the capacity only maintained about 400 mAh g^"1, while the capacity of the Mn₂0₃ material according to the invention after 250 cycles still was around 800 mAh g^"1.

Compared to the state of the art anode material and other reported results on metal oxides, the Mn₂0₃ material with a primary hollow and secondary mesoporous structure of the present invention achieved improved electrochemical performance in specific capacity and cycling stability when used as anode material for energy storage devices. The charge capacity around 1150 mAh g^"1 under 0.1 C was 350 mAh g^"1 higher than the performance of a comparable Mn₂0₃ electrode of 800 mAh g^"1 as shown in example 12. Hence, the present invention provides for electrode material for lithium-ion batteries with an increased density and enhanced power supply and also show the possibility of realizing commercialization.

Claims

1. A method for preparing a mesoporous metal oxide, comprising the following steps: a) providing a metal salt;

b) providing a template;

c) mixing the metal salt of step a) with the template of step b) in a solvent to form a precursor solution and heating the precursor solution to obtain a precipitate; and

2. The method according to claim 1, wherein the N-Cio-26 acyl-glutamic acid is selected from the group of N-Cio-26 acyl-D-glutamic acid, N-Cio-26 acyl-L-glutamic acid, or mixtures thereof.

3. The method according to claim 1 or 2, wherein the acyl group of the N-C 10-26 acyl- glutamic acid has a chain length of > 12 to < 24 carbon atoms, preferably of > 13 to < 21 carbon atoms.

4. The method according to any of the preceding claims, wherein the metal is selected from the group consisting of Al, Mg, Mn, Ni, Co, Cr, B, Ca, Zr, Nb, Mo, Sr, Sb, W, V, Ge,

Sn, Fe, Cu, Zn, and Ti or is a mixture of two or three of these metals, preferably selected from the group consisting of Mn, Zn and Ti.

5. The method according to any of the preceding claims, wherein the metal salt is selected from the group consisting of a metal sulfate, acetate, carbonate, nitrate, chloride, oxalate, and mixtures thereof.

6. The method according to any of the preceding claims, wherein in step b) the template is provided in a solvent, wherein the solvent preferably is a mixture of water and alcohol, wherein the alcohol preferably is selected from the group consisting of methanol, ethanol, glycol, acetone and mixtures thereof.

7. The method according to any of the preceding claims, wherein the mole ratio for the alcohol to the N-Cio-26 acyl-glutamic acid is in a range from > 0.01 mol to < 100 mol alcohol

-5 -2

to > 10^" to < 10^" mol N-Cio-26 acyl-glutamic acid, preferably in a range of > 0.1 mol to < 20

-5 -3

mol alcohol to 5x10^" mol to < 6x10^" mol N-Cio-26 acyl-glutamic acid, more preferably in a range of > 1 to < 5 mol alcohol to 2xl0^"4 mol to < 8xl0^"4 mol N-Cio-26 acyl-glutamic acid.

8. The method according to any of the preceding claims, wherein in the precursor solution of step c) the mole ratio of the metal salt to the template is in a range from > 10^"4 to <

-2 -5 -2 -4

5x10^" mol metal salt to > 10^" to < 10^" mol template, preferably in a range from > 5x 10^" to

-2 -5 -3

< 10^" mol metal salt to > 5x10^" to < 6x10^" mol template, more preferably in a range from > lx 10^"3 to < 5xl0^"3 mol metal salt to > 5xl0^"5 to < 6xl0^"3 mol template.

9. The method according to any of the preceding claims, wherein in the step c), the precursor solution is heated to a temperature in a range of > 40 °C to < 80 °C, preferably in the range of > 50 °C to < 60 °C, and/or is reacted for a time period in a range of > 10 minutes to < 10 hours, preferably in the range of > 2 hours to < 4 hours.

10. A mesoporous metal oxide of the formula M_xO_y wherein 1 < x < 3 and 1 < y < 5, and wherein the metal M is selected from the group consisting of Al, Mg, Mn, Ni, Co, Cr, B, Ca, Zr, Nb, Mo, Sr, Sb, W, V, Ge, Sn, Fe, Cu, Zn, and Ti or of two or three of these metals prepared by the method according to any of the preceding claims.

11. The mesoporous metal oxide of claim 10, wherein the mesoporous metal oxide has a

2 -1 2 -1

BET surface area in a range from > 20 m g^" to < 80 m g^" , preferably in a range from > 30 m 2 g-^"1 to < 75 m 2 g-^"1 , more preferably in a range from > 35 m 2 g-^"1 to < 73 m 2 g-^"1.

12. Electrode material for electrochemical energy storage devices, particularly for lithium ion batteries, prepared by the method according to claims 1 to 9.

13. Electrode comprising a mesoporous metal oxide prepared by the method according to claims 1 to 9 as electrode material.

14. An electrochemical energy storage device, comprising an electrode according to claim 13, particularly a lithium-ion battery, a lithium-ion capacitor or a supercapacitor.

15. Use of a mesoporous metal oxide prepared by the method according to any of the preceding claims as electrode material for electrochemical energy storage devices, particularly as active material for electrodes used in lithium-ion batteries, lithium-ion capacitors and supercapacitors.