2 months project report on li-ion battery

8/11/2019 2 months project report on Li-ion Battery

1/18

1

PROJECT REPORT

MAY-JULY 2013

AQUEOUS RECHARGABLE AND FLEXIBLELITHIUM ION BATTERY

Prepared by

Rahul Kumar

B.Tech Nanotechnology (3rdYear)

Amity Institute of Nanotechnology

Amity University, Noida

Uttar Pradesh


2/18

2

ACKNOWLEDGEMENT

I express my sincere gratitude towards Dr. Prem Kalra, Director, IIT Jodhpur,

Rajasthan for allowing me to undertake my project at IIT Jodhpur, Rajasthan.

I am thankful to Mr. Ritesh Patel and Mr Belal Usmani, for their invaluable

support and encouragement. I am grateful to him for providing me all the facilities

that I have utilized to accomplish my project.

I take immense pleasure, in expressing my gratitude to my guide Dr. Harinipriya

Sheshadri, for her expert guidance and constant encouragement throughout the

period of my project. I am grateful for her motivation, patience and precious time

that she devoted for my project work. It has truly been a wonderful experience to

have worked under her able guidance.

Rahul Kumar


3/18

3

CERTIFICATE

This is to certify that Mr. Aditya Sharma, 3rdyear,B.Tech. Nanotechnology, Amity

University, Noida has undergone a summer training in Energy system of Indian

Institute of technology Jodhpur, Rajasthan for a period of 8 weeks from 12thmayto 14thJuly 2012 on, Aqueous rechargeable and flexible lithium ion battery.

His report contains no confidential or restricted information.

During this period his conduct was good. He was sincere, hardworking and always

willing to learn things.

Dr. Harinipriya Sheshadari

Assistant Professor

IIt Jodhpur, Rajasthan


4/18

4

TABLE OF CONTENTS

Acknowledgements 2

Certificate 3

1.Abstract 6

2.Literature Review 7

2.1Cathode Material(LiMn2O4) 9

2.2Anode Material(CNT) 10

3.Cell Construction 12

3.1 LiMn2O4Cathode Synthesis 12

3.2 CNT Ink Anode Synthesis 12

3.3 Cell Construction 12

4. Data Analysis, results and Interpretation 14

4.1 XRD analysis 14

4.2 SEM analysis 15

5. References 18


5/18

5

LIST OF FIGURES

Figure 1: Lithium Ion battery mechanism 7

Figure 2: XRD graphs of different samples of LiMn2O4Powder 14

Figure 3:SEM images of different sample of LiMn2O4Powder 17


6/18

6

1.Abstract

New and improved materials for energy storage are urgently required to make

more efficient use of our finite supply of fossil fuels, and to enable the effective

use of renewable energy sources. Lithium ion batteries are a key resource formobile energy, and one of the most promising solutions for environment-friendly

transportation. We report the synthesis of Nanostructured LiMn2O4Powder as the

cathode material for rechargeable lithium ion batteries. Synthesis was done by

starch assisted sol-gel method. Multi walled Carbon Nanotubes (MWCNTs) of

average diameter from 10 nm to 20 nm in the form of thin films were used as

anode material. Lithium Sulphate and Agar-Agar solution was used as the

electrolyte for charge transfer between two electrodes. Characterization was done

by powder XRD, SEM, UV and FTIR.


7/18

7

2.Literature Review

A lithium-ion battery is a member of a family of rechargeable battery types in

which lithium ions move from the anode to the cathode during discharge and back

when charging. Li-ion batteries use an intercalated lithium compound as theelectrode material, compared to the metallic lithium used in non-rechargeable

lithium battery. Lithium-ion batteries are common in consumer electronics. They

are one of the most popular types of rechargeable battery for portable electronics,

with one of the best energy densities, no memory effect and only a slow loss of

charge when not in use. You can find them in laptops, PDAs, cell phones and

iPods. They're so common because, pound for pound, they're some of the most

energetic rechargeable batteries available.

Figure-1: Li-ion Battery

Since Sony introduced its model No.-18650 cell in 1990, Li-ion batteries with

excellent electrochemical performance have been manufactured and occupied a

prime position in the market place to power portable and non-portable devices.


8/18

8

There are three main parts of the Li-ion Battery: -

1) Cathode Material

2) Anode Material

3) Electrolyte

Batteries are broadly grouped as primary and secondary batteries. Primary batteries

are single-use devices and cannot be recharged; secondary batteries are also called

rechargeable batteries and can be recharged for many times.

The reason for this relevance is that compared to traditional rechargeable batteries

such as, lead acid and Ni-Cd, the lithium-ion battery shows several advantages,such as lighter in weight, smaller in dimension and higher energy density.

Moreover, although capacity values may be similar to other rechargeable systems,

voltages are approximately three times higher, affording higher energy.

In general, the commercial lithium-ion batteries use graphite-lithium composite,

LixC6, as anode, lithium cobalt oxide, LiCoO2, as cathode and a lithium-ion

conducting electrolyte. When the cell is charged, lithium is extracted from the

cathode and inserted at the anode. On discharge, the lithium ions are released by

the anode and taken up again by the cathode. Owing to the importance of lithium

ion batteries, these cells are still object of intense research to enhance their

properties and characteristics. The searches focus on all aspects of these batteries,

including improved anodes, cathodes and electrolytes. However, most of these

efforts are concentrated in new cathode materials, since the most used cathode

material (LiCoO2) is expensive and is somewhat toxic. The active cathode material

of a secondary lithium ion battery is a host compound, where lithium ions can be

inserted and extracted reversibly during the cycling process.

But with the advent of nanotechnology, the efficiency of Li-ion batteries has been

increasing. Researchers are more focused on increasing the efficiency by using

nanostructured material for cathode and anode.


9/18

9

2.1Cathode Material (LiMn2O4)

The cathode materials for Li-ion batteries are usually oxides of transition metals

due to their high electrochemical. Currently there are three intercalation materials

that are used commercially as cathode materials for rechargeable lithium batteries:

LiCoO2, LiNiO2, and LiMn2O4.

We used the LiMn2O4powder, which is a very promising material for cathode. It

forms a spinel structure, in which manganese occupies the octahedral sites and

lithium predominantly occupies the tetrahedral sites. In this case, the paths for

lithiation and delithiation are a 3-dimensional network of channels rather than

planes. LiMn2O4is lower cost and safer than LiCoO2, but has a lower capacity ascompared to the cathode materials that form the NaFeO2structure.However, the

high cost, toxicity, and limited abundance of cobalt have been recognized to be

disadvantageous. As a result, alternative cathode materials have attracted much

interest. LiMn2O4is one of promising candidate for cathode.Which has a charge

storage capacity of 148 mAh/g. Spinel LiMn2O4 has the advantages of low-cost,

environmental friendliness, and high abundance. One of the challenges in the use

of LiMn2O4 as a cathode material is that phase changes can occur during cycling.

For example, LiMn2O4 cathodes have been field tested in the DC power supply of

an operating telecommunications transceiver. During this test, a relatively rapid

loss of capacity occurred in the first few days, but the rate of capacity loss

subsequently decreased. The initial loss has been attributed to loss of oxygen

during charging. Capacity loss has also been observed during storage due to

dissolution of manganese in the electrolyte, or due to changes in particle

morphology or crystallinity.

The performance of cathode materials can be improved by doping, but the

interpretation of doping effects can be complicated by the interrelations betweendoping and microstructure and morphology, since the microstructure formed can

be affected by the dopant additions. Some examples in which the effects of doping

on the electrochemical properties of the electrode are attributed to the effects of the

dopant on the cathode microstructure or morphology rather than the effects on the


10/18

10

material properties include cesium doping of LiMn2O4, copper-doping of

phosphates and aluminum-doping of LiCoO2.

Another transition metal that has been used as a dopant for cathode materials is

ruthenium, which has been added as a dopant to spinel electrode material.

2.2 Anode Material (CNT)

An anode is an electrode through which electric current flows into a polarized

electrical device. The direction of electric current is, by convention, opposite to the

direction of electron flow.

MWCNTs, with concentric graphene layers spaced 0.34 nm apart, display

diameters from 10 to 20 nm and lengths of hundreds of microns were taken as

anode material for li-ion battery. Carbon nanotubes (CNTs) have displayed greatpotential as anode materials for lithium ion batteries due to their unique structural,

mechanical, and electrical properties. Carbon nanotubes (CNTs), an allotrope of

graphite, have been reported to show much improved lithium capacity compared to

graphite, due to their unique structures and properties. However, due to the

multiple rolled layers, MWCNTs are able to insert Li ions in a way similar to

graphite, making them a promising candidate as an anode material for LIBs.

Except for the inter-planar spacing of graphitic sheets that allows for the

intercalation/deintercalation of lithium ions, the hollow cores of MWCNTs are alsoavailable for lithium ion intercalation. Therefore, the unique structures of

MWCNTs should result in a higher capacity than that of graphite. Much work has

been done to verify the excellent electrochemical performance of MWCNT-based

anode materials in LIBs applications.

CNTs have been reported to display conductivities as high as 106 S/m and 105 S/m

for single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes

(MWCNTs), respectively, and high tensile strength up to 60 GPa. The vertically

aligned MWCNTs also displayed substantially greater rate capability than the non-aligned ones, which emphasizes the important role that structure order plays in

electrode performance. Recently, many investigations have focused on CNT-based

anodes for LIBs with varying success, depending on the treatments employed. This

paper provides an overview of the recent research of CNTs in LIB anode

applications with respect to structural and morphological factors.


11/18

11

It has been suggested that lithium atoms are stored via two mechanisms:

intercalation and alloying. We briefly describe the intercalation and diffusion of Li

at different sites on CNTs. Many studies have been performed in order to

investigate the mechanism by which lithium ions are stored in CNTs, including

theoretical works proposed a surface mechanism by which the naked surface ofCNTs and carbon nanoparticles are able to store lithium species, through

investigation of the electrochemical intercalation of lithium into raw end-closed

CNTs.

It is well known that the morphology of CNTs is of great importance for the

electrochemical performance of LIBs when CNTs are used as anode materials.

This means that the defects, lengths, and diameters of CNTs can influence the

performance of CNT-based anode materials. Generally, there are two widely

applied methods to modify the morphologies of CNTs: chemical etching and ball-

milling. These treatments are reported to result in structural changes and the

formation of surface functional groups on CNTs. The structural changes, including

the lateral defects on the surface of CNTs and the shortening of the length of

CNTs, can increase the Li insertion capacity.


12/18

12

3 Experiment Work

3.1LiMn2O4Cathode Synthesis

All the chemicals were analytically pure. All the chemicals were purchased

by Alfa Aesar and Fisher Scientific. LiMn2O4 powder was synthesizes by starchassisted sol-gel method. A solution of 6.4g starch in 400ml distilled water was

taken and heated at 150c with stirring till it becomes transparent. Then a mixture of

5mM of Manganese nitrate tetrahydrate Mn (NO3)2in 800ml water and solution of

2.5mM Lithium Nitrate LiNO3in 400ml water was added in solution of starch and

initially heated and stirred at 250C for 1h till it becomes homogeneous. Then

temperature was raised till 450C till the solution gets vaporized and precursor was

obtained in the form of foam. Then foam was further dried for 3hours at 400C.

Black powder is obtained after the foam was completely dried. Then powder wasfurther grinded in granite mortar to fine powder. Then powder was calcinated at

700C for 3hours in box furnace. X-Ray diffraction, UV, FTIR and SEM analysis

was done. This powder was further used for making thin sheet of 1g of LiMn2O4

was added in a Solution of 6g Ethyl Cellulose in 50 ml Amyl Acetate under

vigorous stirring for 2h. Then obtained solution was spray coated on PET sheets

and uniform thin films of Cathode were obtained.

3.2 CNT Ink Anode Synthesis

MWCNTs, with concentric graphene layers spaced 0.34 nm apart, display

diameters from 10 to 20 nm and lengths of hundreds of microns were taken as

anode material for li-ion battery. Solution of 6g Ethyl Cellulose in 50 ml Amyl

Acetate was prepared under vigorous stirring for 2h. Then 1g of MWCNT was

added in the solution and continued the stirring for 1h. Then solution was spray

coated on PET sheets of dimension 14.5cm x 9.5cm with the help of spray gun and

a uniform thin layer was obtained.

3.3 Cell Construction

A solution of lithium Sulphate of 1 molar concentration in 100 ml distilled water

and 20 g of Agar-Agar was prepared as electrolyte for Li-ion battery. This solution

was heated for 20 minutes till the solution become viscous gel. Silver paste was

used to make the contacts on both the electrodes to increase the conductivity. The


13/18

13

electrolytic gel was placed between the two electrodes and copper wire was used

for charging the battery. Then the gel become hard, cell was sealed with m-seal.


14/18

14

4 Data Analysis, results and Interpretation

4.1 XRDAnalysis

The powder XRD of LiMn2O

4powder was done by Brukers D8 Advance. The

XRD graphs of different samples have shown below. The material was crystalline

in nature. The hkl values and 2 theta values were matched with standard data.

20 30 40 50 60 70 800

100

200

300

400

500

Intensity

(a.u)

2 Theta

Sample no-1

LiMn2O

4Powder

20 30 40 50 60 70 800

50

100

150

200

250

Intensity

2 Theta

Sample No- 2

LiMn2O

4Powder

20 30 40 50 60 70 800

100

200

300

400

500

Intensity

2 Theta

Sample No-3

LiMn2O

4Powder

20 30 40 50 60 70 800

50

100

150

200

250

300

350

Intensity

2 Theta

Sample No-4

LiMn2O

4Powder

20 30 40 50 60 70 800

100

200

300

400

500

Intensity

2 Theta

Sample No-5

LiMn2O

4Powder

Figure 2: XRD graphs of different samples of LiMn2O4Powder


15/18

15

4.2 SEM Analysis

SEM images were taken from Carl ZEISS SEM EVO 18 edition instrument.

Nanostructures were formed in all the samples synthesized by this method.

LiMn2O4Powder was crystalline and chain was formed due to the starch reaction.SEM images are shown below.


16/18

16


17/18

17

Figure 3: SEM images of different sample of LiMn2O4Powder used as cathode for

the Lithium Ion battery. A scale appears in all the pictures.


18/18

18

5 References

1. J. Braz. Chem. Soc., Vol. 17, No. 4, 627-642, 2006.

2.

Chem. Mater. 2003, 15, 4211-4216.

3.

Materials 2013, 6, 1138-1158.4. Int. J. Electrochem. Sci., 8 (2013) 67756783.5. Materials Science and Engineering R 73 (2012) 5165.

6.Nano Lett., 2008, 8 (11), 3948-3952.7.J. Mater. Chem. A, 2013, 1, 3518.

2 months project report on li-ion battery

Documents