Summary of material science doctoral thesis: Research on the ion exchange of manganese oxide based electrolyte in alkaline ion battery

The purpose of the thesis: Understanding and building manufacturing technology for positive material, which has the ability to exchange and storage of Li+ , Na+ on manganese oxide substrate. Investigating the variation of electrical and electrochemical properties of material systems dependent on technological factors. Therefore, determining the suitable technology for making conductor material and charge/discharge Li+ , Na+ ion with high capacity, energy density, and structural stability.

MINISTRY OF EDUCATION

AND TRAINING

VIETNAM ACADEMY OF

SCIENCE & TECHNOLOGY

GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY

The work was completed at:

Institute of Materials Science - Academy of Science and Technology

Science instructor:

1 Assoc Prof Pham Duy Long

2 Ph D Truong Thi Ngoc Lien

BEGINNING

Recently, energy security and sustainable developments are global challenges that need to be addressed by all nations for their present and future lives Energy sources based on fossil fuels (oil, coal, gas, ) and even nuclear power are now at risk of exhaustion Moreover, the use of fossil fuels also emits CO2 that causes catastrophic climate change and environmental pollution The challenge now is to find, exploit and use clean, renewable and energy sources, which is harmless to the environment to replace these sources of energy Among the clean energy sources having the capability of renewable, wind energy, solar energy has been considered as an alternative energy source with great potential However, these kinds of energy have a huge limitation: often discrete and depending on weather conditions For overcoming these disadvantages and using these energy sources effectively,

it is necessary to have the storage device to store these energies for use when necessary

In the field of research and manufacture of lithium-ion batteries, the three most important basic materials are i /Group of layer-structure LiCoO2 (LCO) material; ii/Group of spinel structure materials of LiMn2O4 (LMO); iii/Group

of olivine structural material of LiFePO4 (LFP) These are materials have high-ability of exchanging and storing H+ and Li+ ions, and they are the basic element for making positive poles in lithium-ion batteries (LIBs)

Over the last two decades, the spinel material of transition metal oxides, particularly the LiMn2O4 compound, has received great attention in the field

of lithium-ion battery research (LIBs) With its popularity, non-toxic spinel material LiMn2O4 has more advantages over LiCoO2 materials

The main problem of LiMn2O4 is the quick reduction in capacity after the first cycle at both room temperature and high temperature Decreasing in storage process or during charge cycle is not well-defined, several causes could be suggested as structural rigidity; lattice distortion effect Jahn-Teller;

Mn dissolved in the electrolyte solution To solve this problem, the research

for Mn to improve capacity as well as stability in the charge cycle Among the doped materials, LiNixMn2-xO4 shows the best stability in discharging/charging process

Another interesting issue attract attention recently is the replacement of conductive material and the charge/discharge of Li+ with conductive materials and the charge/discharge of Na+ in the compound with either MnO2

or V2O5 oxides, which could be used in the manufacture of sodium ion batteries (NIBs: Natrium ion batteries), also known as sodium ion batteries This is a new research direction and the NIBs battery is a candidate for replacing lithium-ion batteries in many areas, especially in the field of large-scale energy storage NIBs battery has many advantages, such as low cost, due to the large capacity of sodium in the Earth's crust, easy to manufacture and environmentally friendly

In Vietnam, the study of lithium-ion battery materials and components has also been studied in a number of institutes such as Institute of Materials Science; Vietnamese Academy of Science and Technology; Hanoi University of Science and Technology; Hanoi Pedagogical University 2; University of Science, Vietnam National University Ho Chi Minh City These research are usually based on a number of specific subjects such as the LiCoO2 positive; Solid Li2 / 3-xLa3xTiO3 solid electrode material Studying materials that can store and conduction has been carried out, achieved many positive results on materials that can store and conduction such as conductive ionic materials LiLaTiO3, LiMn2O4 and started investigating ion battery On that basis we perform:

"Research on the ion exchange of manganese oxide based electrolyte in

alkaline ion battery"

The purpose of the thesis:

 Understanding and building manufacturing technology for positive material, which has the ability to exchange and storage of Li+, Na+

on manganese oxide substrate

 Study the structure, morphology, ionic conductivity, ion exchange and storage of materials depends on technological factors

 Investigating the variation of electrical and electrochemical properties of material systems dependent on technological factors Therefore, determining the suitable technology for making conductor material and charge/discharge Li+, Na+ ion with high capacity, energy density, and structural stability

 Initial testing of ion-alkaline batteries, investigate the capability of charging and discharging, capacity and charge cycle of the battery

Research object of the thesis:

LiNixMn2-xO4 conductivity, charge/discharge Li+ ion spinel structure material and conductive, charge/discharge Na+ ion on the basis of MnO2

material, V2O5 was selected as the object of study of the thesis

The composition of the thesis:

The results of the thesis:

The main results of the thesis have been published in 8 works, including articles in journals and scientific reports at national and international scientific conferences

Chapter 1: OVERVIEW 1.1 Concepts and classification of battery

Battery (French: pile) is a component - an electrochemical cell, which converts chemical energy into electrical energy Since its inception in 1800

by Alessandro Volta, the battery has become a popular energy source for many household items as well as for industrial applications

According to the mechanism of operation, we can summarize the two main types of batteries are chemical (electrochemical) and physical batteries The chemical batteries are further divided into primary and secondary batteries The alkaline battery is a rechargeable battery or secondary battery

1.2 A brief history of battery development

In 1938, archaeologist Wilhelm Konig discovered a few clay pots that looked strange when he was excavating in Khujut Rabu, a suburb of Baghdad, Iraq today Vessels of about 5 inches (12.7 cm) contain a copper-coated iron rod dating back to the 200 BC Tests have shown that these vases could previously have contained acidic compounds such as vinegar or wine Konig believes these vases could be ancient batteries

In 1799 Italian physicist Alessandro Volta created the first battery by stacking layers of zinc, cardboard or cloth that had saturated silver and silver Although not the first device that can generate electricity, it is the first to produce long lasting and stable electricity

The battery came in 1859, when French physicist Gaston Plante invented the lead-acid battery With the cathode being a lead metal, the anode is lead dioxide and uses sulfuric acid as an electrolyte

1.3 History of rechargeable lithium-ion batteries

In June 1991, Sony introduced lithium-ion batteries (LIBs) to the market, and since then LIBs has dominated the small rechargeable battery market In

2002, small-volume LIBs were produced in the world of 752 million units The market has an overall growth rate of about 15% per year LIBs currently have an energy reserve of between 200 ÷ 250 Wh/l and 100 ÷ 125 Wh/kg and are proven to be extremely safe in bulk shipments, with very few safety incidents

1.4 Composition, principle of operation of ion battery - Lithium

Figure 1.4 illustrates the working principle and basic structure of the Li-ion battery The reversible reactions occurring in the electrodes are described as equations (1.1) and (1.2)

The reaction occurs at the poles:LiCoO2  Li1-x CoO2 +xLi+ + xe- (1.1) The reaction occurs at the cathode: xLi+ + xe- + C6  Li (1.2)

to escape from the electrode If the ion injection/exiting process is reversible, lithium batteries have a high number of cycles

1.5 Materials for Li-ion batteries

The structure of the rechargeable Li-ion battery consists of three main parts: positive electrode (cathode); negative electrode (anot); electrolyte system

Cathode material

With the advantages of cost, availability and good electrochemical properties, carbon is the perfect cathode material for Li-ion batteries In addition, some other electrodes have been studied such as polar silicon, polar silicon, etc However, due to some limitations, they are rarely applied

Electrolyte

It is easy to see that the electrolysis of the battery is highly dependent on the electrolyte solution because it can support the highly active electrode Accordingly, the use of electrolyte solution must be based on the

Figure 1.4: Illustrates the working principle and basic

structure of the Li-ion battery.

interdependence between the activity of the material and the electrolyte solution

1.6 General information about lead material and ion accumulation/discharge

Figure 1.8: Illustrate the formation of host-guest compound

Families of materials that are capable of exchanging and storing lithium ions are usually oxide materials or compounds of these oxides with lithium

A fundamental characteristic of this family of materials is that in their

Figure 1.5 Crystalline structure of basic materials for Li-ion

batteries

Only subunits are ionic or molecular guest

Indicates the empty position in the host structure

Directional input / output of ion

structure there exist channels (in one dimension or in many dimensions) with sufficiently large dimensions that allow small ions such as Li+; H+ easily injected into or out of the crystal lattice Then the penetration of small "guest" particles (ions, molecules) into a solid "host" in which the network structure exists vacant positions It is possible to illustrate the formation of host-guest compound by shape 1.8

1.7 Li + ion positive electrode

Spinel material LiMn 2 O 4

LiMn2O4 is a spinel family

structure A[B2]O4, belonging

to the space group Fd-3m The

oxygen anion occupies the 32e

position of the space group; the

cations Mn occupy the

octahedral position Oh (16d),

the positions Oh (16c) are

empty, and the tetrahedral sites

T (8a) are the occupying cations (Figure 1.11) Each tetrahedron 8a has the same faces with 4 octahedral octagonal positions, thus forming the channel for the diffusion of the cationic Li as follows:

8a  16c  8a  16c (hình 1.11b) When Li+ ion accumulation/discharge occurs in λ - MnO2, electrons are also input/output to ensure electrical neutralization

The Li+ ion charge on λ - MnO2: Mn4+ + e  Mn3+ (1.16) The Li+ ion process escapes λ - MnO2: Mn3+ - e  Mn4+ (1.17)

Material LiNi x Mn 2-x O 4

The problem that hinders the practical application of spinel-Mn is the cyclic capacity reduction in both spinel/lithium and spinel/carbon batteries, especially at high temperatures It has been found that replacing part of Mn

in LiMn2O4 with metal cations such as Li, Co, Ni, Al, Mg, Cr, Fe, can improve the battery's endurance Furthermore, replacing F and S in the

Figure 1.11: Fd3m field variable spinel

structure

oxygen position is also an effective way to improve storage time and release stability

Among LiMn2O4's doped materials, the LiNixMn2-xO4 spinel is one of the most potent polar materials for the development of high-energy lithium-ion batteries The high voltage of LiNixMn2-xO4 is due to the reversible oxidation

of Ni2+/Ni3+ and Ni3+/Ni4+ occurring respectively at 4.70 and 4.75 volts during Li+ ion injections The high operating voltage and theoretical capacity

of the LiNixMn2-xO4 (146.7 mAh/g) allows for the highest energy density of commercially available materials such as LCO, LMO, LFP and NMC

1.8 Na + ion electrode material

Currently, sodium ion battery (NIBs) are emerging as a candidate for replacement of lithium ion batteries in many areas, especially in the field of large-scale energy storage NIBs have the advantage of being cheap because

of the high volume of sodium in the earth's crust (2.6% of the crust), simple manufacturing methods and environmental friendliness

1.9 Na + ion electrode material on MnO2 substrate

Many positive materials for NIBs have been published as NaMO2 (M = transition metal), tunneling material Na0,44MnO2, NaMnO4 material, etc In objects The nanoparticles Na0,44MnO2 are very interesting materials

1.10 Na + ion electrode material on V 2 O 5

Vanadium pentoxide (V2O5) has been reported as an attractive material for LIBs because of its theoretical capacity (around 400 mAh/g), not air sensitive, and low cost materials Previous studies have described the electrical performance of V2O5 as the positive material for LIBs Recently,

V2O5 material has also been reported as a potential positive material for NIBs

Chapter MANUFACTURING OF METHODS AND

METHODS OF RESEARCHING OF LONG-TERM MATERIALS 2.1 Modeling methods

There are many different methods of making materials Within the framework of this thesis, we selected solid phase reaction method, sol-gel method for making LiNixMn2-xO4 material and hydrothermal method for

making Na0.44MnO2 material These are simple technological methods, highly economical and can be produced in large quantities, so we chose to make LiNixMn2-xO4 and Na0,44MnO2 materials

2.2 Experimental production of positive materials

Experimental production of materials LiNi x Mn 2-x O 4

Material samples of LiNixMn2-xO4 made with sol-gel and solid phase reaction are denoted in table 2.1 and 2.2

Table 2.1: Table of LiNi xMn2-xO4 doped Ni with concentration x = 0; 0,05; 0.1 and 0.2 are synthesized by sol-gel at 300 ° C; 500 ° C; 700 ° C and 800 ° C

Experimental production of Na 0.44 MnO 2 material by hydrothermal method

Table 2.3: Summary table of NaxMnO2 material by hydrothermal method at 185 °C, 1900

°C, 195 °C, 200 °C and 205 °C

Temperature 185 C 190 C 195 C 200 C 205 C Sample symbol T185 T190 T195 T200 T205

2.3 Experiment on making thin films of positive materials

Materials LiNixMn2-xO4 (Na0,44MnO2; V2O5) was mixed with carbon black (super P and KS4) and polyvinylidenefluoride (PVDF) in N-methyl-pyrolidone (NMP) in a 70:20:10 mass ratio Crushed marbles to form a muddy solution This solution is coated on a thin aluminum foil with a thickness of 15 μm and then dried at 100 ° C by vacuum furnace for 12 hours

to obtain a polar leaf

STRUCTURAL CHARACTERISTICS AND

EFFICIENCY OF MATURATED MATERIALS MANUFACTURED 3.1 Structural and morphological characteristics of LiNi x Mn 2-x O 4

material

Morphological characteristics of the LiNi x Mn 2-x O 4 material system

The morphology of the LiNixMn2-xO4 material synthesized by both phase and sol-gel methods showed that the laws of variation had distinct similarities and differences

solid-a) Similar

By increasing the incubation temperature during synthesis, the crystalline grain sizes for both non-Ni and Ni substitution materials increased According to the increase in the ratio of Ni atoms to Mn, the particle size decreases slightly, while the grain change varies from round to sharp

+ The change in grain size from round to sharp is also significantly different Solid-phase materials, when increasing the substitution rate of Ni, produce significantly more granular particles than sol-gel particles

The structure of the material LiNi x Mn 2-x O 4

Figure 3.14: XRD schema of LiNix Mn 2-x O 4 with Ni substitution rate (x = 0 and 0.05) by solid phase method at 800 ° C, 850 ° C and 900 ° C.

Figure 3.15: XRD diagram of LiNix Mn 2-x O 4 material with Ni x = 0.1 (a) and x = 0.2 (b) synthesized by solid phase modification at 800 ° C, 850 ° C and

Figure 3.16: XRD diagram of LiNi xMn2-xO4 material with Ni substitution x = 0 (a) and