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 - TA ANH TAN RESEARCH ON THE ION EXCHANGE OF MANGANESE OXIDE BASED ELECTROLYTE IN ALKALINE ION BATTERY (SPECIALITY) MAJOR: ELECTRONIC MATERIALS Code: 9440123 SUMMARY OF MATERIAL SCIENCE DOCTORAL THESIS HANOI - 2018 The work was completed at: Institute of Materials Science - Academy of Science and Technology Science instructor: Assoc Prof Pham Duy Long 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 focuses on partially replacing the metal ions such as Co, Ni, Al, Mg, Cr, Fe 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 largescale 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: Preamble Chapter 1: Overview Chapter 2: Fabrication of samples in experiment and materials research methods Chapter 3: Structural characteristics and morphological of positive materials Chapter 3: Electric and electrolytic properties of positive material systems General conclusion The results of the thesis: The main results of the thesis have been published in 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 inches (12.7 cm) contain a coppercoated 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) During the discharge process, the lithium ions move to the positive electrode through the conductor and fill in the positive electrode, which is usually made from Figure 1.4: Illustrates the working principle and basic structure of the Li-ion battery + Li containing LiCoO2, LiMn2O4, LiNiO2 or V2O5 At the same time, the electrons move in the external circuit through the load resistor The electromotive force is determined by the difference in electrochemical potential between the lithium in the cathode and the lithium in the polarity When charged to the battery, the positive potential on the positive electrode causes the lithium ion 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 interdependence between the activity of the material and the electrolyte solution Anode materials Most studies of positive materials for lithium ion batteries focus on three types of materials The first is a group of materials with a structure of LiMO2 Figure 1.5 Crystalline structure of basic materials for Li-ion batteries (M = Co, Mn, Ni) with an anionic or nearly tightly packed anion structure in which the alternating layers between the anion plates are occupied by a transition metal Next the oxidation activity is reduced and then lithium inserted The remaining layers are mostly empty (Figure 1.5) 1.6 General information about lead material and ion accumulation/discharge Only subunits are ionic or molecular guest Indicates the empty position in the host structure Directional input / output of ion 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 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 LiMn2O4 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), Figure 1.11: Fd3m field variable spinel the positions Oh (16c) are structure empty, and the tetrahedral sites T (8a) are the occupying cations (Figure 1.11) Each tetrahedron 8a has the same faces with 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) + 3+ 4+ The Li ion process escapes λ - MnO2: Mn - e  Mn (1.17) Material LiNixMn2-xO4 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 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 V2O5 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 10 + 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 LiNixMn2-xO4 Figure 3.14: XRD schema of LiNixMn2-xO4 with Ni substitution rate (x = and 0.05) by solid phase method at 800 ° C, 850 ° C and 900 ° C Figure 3.15: XRD diagram of LiNixMn2-xO4 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 LiNixMn2-xO4 material with Ni substitution x = (a) and 0.05 (b) synthesized by sol-gel method at 300 ° C; 500 ° C; 700 ° C and 800 ° C 13 Figure 3.17: XRD diagram of LiNixMn2-xO4 material with Ni substitution x = 0.1 (a) and 0.2 (b) synthesized by sol-gel method at 300 ° C; 500 ° C; 700 ° C and 800 ° C The X-ray diffraction patterns (Fig 3.14 ÷ 3.17) of samples S0, S1, S2 and S3 were synthesized by solid phase reaction at 800 ° C, 850 ° C and 900 ° C, G1, G2 and G3 synthesized by solgel method at 300 ° C, 500 ° C, 700 ° C and 800 ° C completely give us diffraction peaks in accordance with a single standard tag, JPCDS No 35-072 Figure 3.19: Raman scattering patterns G0-700 (a) and G2-700 (b) of the cubic-spinel structure of space Fd-3m Combined with the Raman scattering spectra shown in Fig 3.19, it was found that LiNixMn2-xO4 material was synthesized by doping Ni with a rate of x = ÷ 0.2 by both sol-gel and solid-phase methods has successfully replaced the positions of Mn Effect of tempering temperature on the structure of the LiNi xMn2-xO4 material system 3.1.3.1 Effect of incubation temperature on the network constants of LiNi xMn2xO4 material Figure 3.20, the constant-change of LiNixMn2-xO4 material produced Symbols S0; S1; S2 and S3 correspond to samples with Ni substitution rates (x = 0, 0.05, 0.1 and 0.2) synthesized at different temperatures Same as samples G0; G1; G2 and G3 are made by sol-gel method The graph shows that the network constant of the material system increases slightly as the 14 tempering temperature increases in both methods of manufacture For the solid-phase method, the net increase was 0.007 Figure 3.20: Graph of the dependence of crystalline lattice Å when the constants of solid and liquid phase (a) and sol-gel (b) materials on tempering temperature tempering temperature increased from 800 ° C to 900 ° C, and for the average sol-gel method the net increase was 0.015 Å as the tempering temperature increased from 300 ° C to 800 ° C The increase in crystalline lattice constant for the LiNixMn2-xO4 material system can be explained by the Figure 3.21: The dependence of crystalline lattice constants of solid and liquid phase (a) and sol-gel (b) materials on the migration from replacement ratio of Ni Mn4+ to Mn3+ (LS or HS) and the migration from Mn3+ (LS) to Mn3+ (HS) when the tempering temperature increases 3.1.3.2 Effect of substitution rate Ni on lattice constant of LiNixMn2-xO4 material Figure 3.21 shows that the crystalline lattice constants of the fabrication material are reduced as the Ni phase ratio increases For the solid-phase method, the network constant decreases to 0.022 Å when the replacement rate of Ni increases from x = to 0.2, and for the average sol-gel method the network constant decreases to 0.023 Å When the replacement rate of Ni increases from x = ÷ 0.2 LiNixMn2-xO4 has a more stable crystalline 15 structure order and Ni doped material promises better electrochemical properties than non-doped materials 3.2 Structural and morphological characteristics of NaxMnO2 material Influence of temperature during hydrothermal to the structure and morphology of NaxMnO2 material 3.2.1.1 Influence of temperature during hydrothermal to morphology of NaxMnO2 material As the temperature increases, the samples change from granular to nanowire At 205 ° C the material obtained is completely nanosized in the form of approximately ~ 30 ÷ 50 nm and long from several hundred nm to tens of μm 3.2.1.2 Effect of temperature during hydrothermal to the structure of NaxMnO2 material Figure 3.29: XRD scheme of Na0.44MnO2 hydrothermal at 185 ° C for 96 hours Figure 3.33: XRD scheme of Na0.44MnO2 hydrothermal at 205 ° C for 96 hours Figures 3.29 and 3.33 are the X-ray diffraction patterns of the samples T185 and T205 The observation in Figure 3.29 shows that even at 185 ° C hydrothermal temperature, diffraction peaks of the Na0.44MnO2 phase exist along with the diffraction peaks of the Mn3O4 precursor material The content of Na0.44MnO2 and Mn3O4 were respectively 34.4% and 65.6% As the temperature rises, the Na0.44MnO2 content in the material is also increased At an incubation temperature of 205 ° C, the XRD spectrum of the sample obtained showed no presence of the manganese oxide material (Figure 3.33) 16 Instead, a rich Na-phase was obtained with the formula Na0.7MnO2.05 This phase appearance may be due to excess Na diffusion into the Na0,44 MnO2 network Figures 3.34, 3.35 and 3.36, hydrothermal materials at 205 ° C for 72 h; 48 h and 96 h then heat up The absence of both the precursor phase and the product phase clearly indicates that the hydrothermal process has occurred in several steps before the final product is Na0,44MnO2 Figure 3.34: Nuclear model XRD NaxMnO2 hydrothermal at 205 ° C for 72 hours Figure 3.35: Nuclear model XRD NaxMnO2 hydrothermal at 205 ° C for 48 hours Figure 3.36: Nuclear XRD pattern of NaxMnO2 hydrothermal at 205 ° C for 96 hours and incubation of 600 ° C for hours 3.3 Structural and morphological characteristics of V2O5 powder material V2O5 powder (99.7%, Alfa Aesar) was used with the X-ray diffraction pattern in Fig 3.42d The diffraction peaks indicate that it belongs to the JPCDS card number 41-1426 with the orthogonal crystal structure of the Pmmn space group X-ray diffraction showed that V2O5 powder was single phase The lattice parameters of V2O5 are 3.39 (d): V2O5 X-ray diffraction calculated by the Unitcell software Figure pattern based on the diffraction peaks 17 marked by Miller indices in Figure 3.42d The volume of the elemental cells and the network constants a, b, and c of V2O5 are respectively 179.3315 (Å) 3; 11.5121 Å; 3.5644 Å and 4.3704 Å Chapter 4: ELECTRIC AND ELECTRICITY MATERIALS OF MANUFACTURED ORGANIC MATERIALS 4.1 The ionic conductivity of the positive material system In Figure 4.4, the typical Nyquist graph in the planar plane represents the virtual part Z dependence on the real part Z of the synthetic material LiNixMn2-xO4 at 700 ° C, measured at room temperature The total spectrum is only two semicircles A semicircle in the high frequency region from MHz to a few tens Hz, they are attributed to the lithium ion Figure 4.4: Nyquist graph of LiNixMn2xO4 with Ni (x = 0; 0.1 and 0.2) conductance in the particle and a synthesized by Sol-gel at 700 ° C (a) semicircle in the low frequency and the intercept of a semicircle on the Nyquist graph (b) region is attributed to the ionic conductivity at the grain boundary The total resistance (Rb + Rgb) and the block resistance (Rb) of the samples are thus obtained correspondingly from the right and left stop points of the semicircle to the actual axis Li+ ionic conductivity of the material LiNixMn2-xO4 4.1.1.1 Effect of Ni replacement ratio and tempering temperature on ion conductivity of the composite material by sol-gel Figure 4.11 shows that the lithium ion conductance of the sol-gel synthesized LiNixMn2-xO4 material depends on the nickel replacement ratio as well as the composite temperature LiNixMn2-xO4 substitute Ni x = 0.1 yields the best lithium ion conductivity improvement: G2-700 is annealed at 700 °C with the largest total conductivity σtp = 19,773 × 10-5 S.cm-1 while 18 sample G0-500 (unmixed and tempered at 500 °C) had the smallest total conductance σtp = 0.111 × 10-5 S.cm-1 Similarly, Figure 4.12 of the LiNixMn2-xO4 material is synthesized by solid phase reaction The Figure 4.11: The influence of Ni phase to Ion conductivity of LiNixMn2-xO4 composite by sol-gel method (G300, G500, conductance of the G700, and G800 are symbols of the samples with incubation at the same temperature 300 ° C, 500 ° C, 700 particle increases ° C and 800 ° C) with increasing nickel replacement, the marginal conductance increases with increasing nickel replacement but Figure 4.12: Influence graph of Ni phase to Ion conductivity of LiNixMn2-xO4 composite by solid phase method (S800; S850 reaches the extreme and S900 are samples of incubated samples at 800 ° C at x = 0.1 and then 850 °C and 900 °C decreases The influence of the ionic conductivity of the material on the incubation temperature is not clear The maximum conductance value for the S3-850 sample is σtp = 2,237 × 10-5 S.cm-1 and the smallest value belongs to the sample S2-800 with the magnitude σtp = 0.753 × 10-5 S cm-1 4.1.1.2 Na + ion conductivity of the positive material NaxMnO2 Figure 4.15 shows that the grain conductance and grain conductance are dependent on the temperature of the hydrothermal process (Table 4.3) The results show that the grain conductance of the material is not significantly different according to the temperature of the hydrothermal process (from 0.319.10-3 S.cm-1 to 0.703.10-3 S.cm-1) changed quite a bit (from 6,757.105 S.cm-1 to 31,068.10-5 S.cm-1) Total conductivity reached maximum value 19 at σtp = 19,707.10-5 S.cm-1 belongs to form T205 This sample of T205 after re-crystallization at 600 ° C for hours gave rise to ion conductivity σtp = 31,661.10-5 S.cm-1 4.2 Electrochemical Properties of Positive Materials The electrochemical characterization of the conduction Figure 4.1: Nyquist plot of the NaxMnO2 system and Li+ ion charge/discharge composite system by hydrothermal method at 185 ° C; 190 ° C; 195 ° C; using LiNixMn2-xO4 is positive 200 ° C and 205 ° C 4.2.1.1 The electrochemical nature of lithium ion batteries using LiNixMn2-xO4 is positive Load measurements of LiNixMn2-xO4 electrode materials were carried out with a cathode-component configuration of the SnO2 tin oxide electrode, an electrolyte solution used as M NaClO4 in a PC (propylene carbonate ) Measurement of the load is measured by the Autolab PSGTAT30 electrochemical system with a voltage in the range of V ÷ V with the discharge current at 0.5 C The charge/discharge curves of the samples are shown in the capacitive representation The maximum discharge was 79.7 mAh/g for G2-700 (LiNixMn2-xO4 doped Ni with x = 0.1 synthesized by sol-gel at 700 ° C) at most 44.9 mAh/g for the S0-900 (LiNixMn2-xO4 doped Ni with x = synthesized by solid phase at 900 ° C) The electrochemicality of the lead system and the Na+ ion charge/discharge using Na0.44MnO2 are Figure 4.17: Load line of solidified positive LiNixMn2-xO4 material at 900 ° C 20 Injection/discharge of Na+ ion of Na0,44MnO2 material Figure 4.20 The C-V spectra of the electrode exhibit a distinct reduction in the oxidation peak corresponding to the Na+ ion Figure 4.20: C-V spectra of untreated T205 (a) and T205U600 injection and with 600 ° C incubation for hours (b) discharge from the electrolyte solution into and out of the electrode material Figure 4.20b is the C-V characteristic spectrum of the electrodes from the T205 after recrystallization, suggesting better ion exhalation 4.2.2.1 Injection/discharge of Li+ ion of Na0,44MnO2 material Figure 4.22 shows the C-V spectrum of the T205U600 using an electrolyte solution of 1M lithium salts, dissolved in deionized water (Li + ion electrolyte) Thus we can conclude that the Na0.44MnO2 material synthesized by hydrothermal method at 205 ° C not only has good Na + ion repellency, but Figure 4.22: C-V spectra of T205U600 also Li+ ion exiting ability with LiNO3 Li-ion electrolyte 4.2.2.2 The electrochemical nature of solution lithium ion batteries using Na0,44MnO2 is positive Figure 4.23, illustrates the charge/discharge curves in cycles 1, 10, and the 20 th cycle with a speed of 0.1 C; Voltage 2.0 ÷ 4.0 V The discharge capacity of cycle 1; 10 and cycle 20 are 62.7 mAh/g, 64.0 mAh/g and 65.8 mAh/g respectively It can be seen that both charge and discharge curves exhibit voltage stabilization demonstrations that the Na0.4MnO2 material has been phase-shifted during the sodium ion injection into the material 21 structure A careful observation of the discharge curves reveals five voltage stabilization positions at 3.4; 3,2; 2.9; 2.6 and 2.4 V, which corresponds to the phase change during the sodium ion penetration of the Na0,44MnO2 material The charge curve (load) displays constant voltage values at 3.5; 3,25; 3.0; 2.7 and 2.5 V, corresponding to the Figure 4.23: First, 10th, and 20rd load/discharge curves of positive process of sodium ions break off the material Na0.44MnO2 at 0.1C; Voltage 2.0 ÷ 4.0 V structure of Na0.44MnO2 In addition, the charge and discharge curves are similar in shape and superimposed on each other From this result it can be predicted that material Na0,44MnO2 has a large charge/discharge cycle Figure 4.24 describes the change in battery capacity by the charge/discharge cycles and the coulombic efficiency of the positive material Na0.44MnO2 at line 0.1C; Voltage in the range of 2.0 ÷ 4.0 V Charge/discharge capacity increased from 66.2/62.7 mAh/g to 68.4/64.0 Fig 4.24: Charge/discharge cycles and coulombic performance of positive mAh/g in the first 10 cycles Capacity material Na0.44MnO2 at 0.1 C; voltages 2.0-4.0 V was maintained steady for the next 30 cycles and then slowly decreased to 46.9/41.1 mAh/g after 70 cycles The coulombic performance of the material reached 90% and this value was stable throughout 70 cycles The electrochemical characterization of the lead material and the sodium ion accumulation/discharge using V2O5 is positive In this study, the first commercial V2O5 crystals were used together with carbon black (super P and KS4) as conductors to make positive pole for NIBs batteries Figure 4.26a shows that the first discharge curves of the V2O5 cell 22 were obtained at 0.1 C between 1.0 V and 3.5 V During the first Na + ion intercalation, the discharge capacity was approximately 208 mAh/g In the first stage, the two voltage positions observed at the discharge curve indicate the formation of NaxV2O5 by the Na Figure 4.26: First cycle discharge/discharge curve of V2O5 battery with current 0.1 C (a); Charge/discharge curves ions intermingled from second to fourth cycles of V2O5 with 0.1 C (b); The with the V2O5 capacity of the V2O5 battery (c) and the cyclical efficiency of the V2O5 battery at the 0.1 C (d) charge/discharge line structure The electrochemical profiles of the second to fourth cycles of the V 2O5 cell are shown in Figure 4.26b Figure 4.26c illustrates the electrochemical configuration of a V2O5 cell at different discharge rates The second cell cycle cell mass at 0.1 C is 85.9 mAh/g and the discharge capacity at the initial cell cycle at 0.2C; 0.5 C and 1.0 C respectively 66.2 mAh/g; 55.1 mAh/g and 42.2 mAh/g Operating cell showed that when the discharge current rate from 1.0 C back to 0.1 C, the discharge capacity returned to the initial value, which shows that the NaxV2O5 structure is very stable for good Rapid application of Na + ion The efficiency of the loading/unloading process starts from the second to the 40th cycle of the V2O5 cell at 0.1 C at a voltage range of 1.0 V to 3.5 V as shown in Figure 4.26d Secondary discharge capacity is 97.2 mAh/g and decreases to 59.5 mAh/g after 40 cycles Electrochemical efficiency retained after 40 cycles was 61.2% Figure 4.28 is the X-ray diffraction pattern of the original positive and positive polarizer emitted up to 1.0 V compared to the X-ray plot of the V2O5 23 powder The diffraction peaks are marked (•) corresponding to the aluminum phase of the positive pole On the X-ray diffraction pattern of the positive poles when discharged to 1.0 V (Figure 4.28c), all vertices of the V2O5 phase disappeared, X-ray diffraction pattern indicating peak vertices of NaxV2O5 phase and substrate This shows that the V2O5 phase completely changes into phase NaxV2O5 (JCPDS No 24-1157) 4.3 Tested for Lithium ion battery Figure 4.28: Diffraction diagram of powder V2O5 (a); positive preparation (b); positive pole after discharge to 1.0 V (c) Figure 4.29: LiMn2O4 electrodes (a), Li-ion battery configuration (b) From the LiNixMn2-xO4 material, we have conducted experiments on making lithium ion batteries The poles and poles are selected as follows: + cathode is made of SnO2 material + Electrolyte is a solution of 1M LiClO4+PC impregnated with absorbent paper The diagram is shown in Figure 4.29b The electrode has an Figure 4.3: Use the battery to light up area of cm × 1.5 cm the LED bulb To test the performance of the battery, we used a battery to power a 3V LED bulb As a result, the bulb is bright and maintained for quite a long time (Figure 4.30) 24 CONCLUSION Successfully fabricated the positive electrode system for LiNixMn2-xO4 lithium ion battery (with x = 0, 0.05, 0.1 and 0.2) in the form of nanoparticles in both directions The method is a solid phase reaction of the MnO2, NiO and Li2CO3 salts and the sol-gel method from the corresponding acetate salts  The results show that the LiNixMn2-xO4 system is single phase and the structural and morphological characteristics of the material are strongly dependent on the technological conditions such as reaction temperature, tempering temperature and both the component of Ni replaced (x from ÷ 0.2) By increasing the Ni content of LiNixMn2-xO4 crystalline nanoparticles for sharper edges or higher structural stability For sol-gel the size of the nanoparticles varied from about 30 ÷ 60 nm when the incubation temperature was below 700 ° C and increased markedly when the heat was increased and reached a value of 500 nm at 800 ° C Whereas in the case of manufacture by solid phase reaction the particle size is much larger from μm to μm The solgel method is superior due to the ease of fabrication and adjustment of fabrication conditions to obtain single-phase LiNixMn2-xO4 materials The control of Ni content replaced the Mn in the range of x = 0.05 ÷ 0.2 and the tempering temperature was above 700 C for higher structural stability  The results of electrochemical characterization and discharge capacity of the LiNixMn2-xO4 electrode material system showed that the material was shown to be well reversed during lithium ion exiting Tolerance of lithium ion of sample G2-700 (corresponding to x = 0.1 and tempering temperature T = 700 ° C) synthesized by sol-gel method for highest ion conductivity σtp = 19,773.10-5 S.cm-1 also gives the highest discharge capacities of 85.5 mAh/g and 79.7 mAh/g, respectively This value is about 70% of the theoretical capacity, suggesting that the fabrication material could be used as a positive electrode in lithium ion batteries later The conductivity of the material system and NaxMnO2 increases as the temperature of the hydrothermal process increases and depends on the incubation process The ionic conductivity value of the hydrothermal sample is 205 °C and then incubated at 600 °C in hours for the highest ionic conductivity is σtp = 31,661.10-5 S.cm-1 Results of the discharge test of the 25 Na0.44MnO2 positive poles in the sodium ion battery configuration for the highest load and discharge capacities were 67.5 mAh/g and 65.8 mAh/g, respectively Capacity is maintained around 85.3% after 50 cycles; Coulombic performance reaches 90% in 70 cycles The conductivity of the material system and NaxMnO2 increases as the temperature of the hydrothermal process increases and depends on the incubation process The ionic conductivity value of the hydrothermal sample is 205 °C and then incubated at 600 °C in hours for the highest ionic conductivity is σtp = 31,661.10-5 S.cm-1 Results of the discharge test of the Na0.44MnO2 positive poles in the sodium ion battery configuration for the highest load and discharge capacities were 67.5 mAh/g and 65.8 mAh/g, respectively Capacity is maintained around 85.3% after 50 cycles; Coulombic performance reaches 90% in 70 cycles Sodium ion battery using V2O5 powder material is positive for the first cycle discharge capacity of approximately 208 mAh/g but the second cycle has a very strong decrease of only 80 mAh/g The first reduction in discharge after discharge was explained by the structure of V 2O5 converted to NaxV2O5 structure when Na+ ions were injected and kept stable during subsequent charge/discharge processes resulting in the number of ion Na+ has the potential to significantly reduce exchange rates After 40 cycles, the discharge capacity still retains 61.2% of the discharge capacity of the second cycle The capacity of the battery to be charged/discharged at 1.0 C retains 49.1% of the charge of the charging/discharging battery at 0.1 C and the capacity returns to its initial value when charging/discharging returns at 0.1 C In addition, the lithium ion battery module based on the LiNixMn2-xO4 material system for positive polarity and cathode using SnO2 oxide has also been tested The components work well in the range of ÷ 3,5 V which can light LED bulbs 26 PUBLICATIONS Tan Ta Anh, Chien Dang Tran, Phuong Do Thi, Oanh Nguyen Thi Tu, Mai Do Xuan, Chung Vu Hoang, Chi Le Ha, Long Pham Duy, Investigation of sodium manganese oxide nanowires synthesized by hydrothermal method for alkaline ion battery Communications in Physics, Vol 24, No (2014), pp 233-238 Tạ Anh Tấn, Đặng Trần Chiến, Le Huy Sơn, Nghiên cứu chế tạo vật liệu dương cực composit LiMn2O4/CNTs ứng dụng cho pin liti, Tạp chí khoa học trường Đại học Thủ Đô Hà Nội, Số 18, (2017) Tr 125 – 131 Ta anh Tan, Nguyen Sy Hieu, Le Ha Chi, Dang Tran Chien, Le Dinh and Pham Duy Long, Structure and electrochemical impedence of LiNixMn2-xO4, Communications in Physics, Vol 26, No (2016), pp 361368 Tan Anh Ta, Long Duy Pham, Hieu Sy Nguyen, Chung Vu Hoang, Chi Le Ha Chien Dang Tran, Hoa Nguyen Thi Thu and Nghia Nguyen Van, Electrochemical performance of Na0.44MnO2 synthesized by hydrothemal method using as cathode material for sodium ion batteries, Communications in Physics, Vol 27, No (2017), pp 143-149 Nguyen Van Nghia, Pham Duy Long, Ta Anh Tan, Samuel Jafian & IMing Hung, Electrochemical Performance of a V2O5 Cathode for a Sodium Ion Battery, Journal of Electronic Materials Vol 46, No (2017) pp 3689– 3694 Đặng Trần Chiến, Tạ Anh Tấn1, Lê Huy Sơn, Đặng Trần Chiến, Phạm Duy Long, Vật liệu Spinel LiNixMn2-xO4 (x =0; 0.1; 0.2) tổng hợp phương pháp phản ứng pha rắn sử dụng làm dương cực cho pin liti – ion với âm cực SnO2, Tạp chí khoa học trường Đại học Thủ Đô Hà Nội, Số 18, (2017) Tr – 14 Tạ Anh Tấn, Đặng Trần Chiến, Phạm Duy Long, Sự ảnh hưởng nhiệt độ trình thủy nhiệt tới việc hình thành dây Na0.44MnO2, Tạp chí khoa học trường Đại học Thủ Đô Hà Nội, Số 18, (2017) Tr 102 – 111 Ta Anh Tan, Le Huy Son, Dang Tran Chien, Influence of nisubstitution for Mn on the structure and ionic conductivity of LiNixMn2-xO4 spinel materials prepaired by the sol-gel method, Scientific Journal of Hanoi Metropolitan University, Vol 20, (2017) Pp 75-86 27 ... 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. .. 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... 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