Title Technologies of Lithium Ion Polymer Battery

Author(s) Roh, Young Bae

Citation 電気材料技術雑誌. 14(2) P.143-P.148

Issue Date 2005-07-15

Text Version publisher

URL http://hdl.handle.net/11094/76828

DOI

rights

Note

Osaka University Knowledge Archive : OUKAOsaka University Knowledge Archive : OUKA

https://ir.library.osaka-u.ac.jp/

Osaka University

電気材料技術雑誌第14巻第2号J.Soc.Elect.Mat.Eng. Vol.14, No.2, 2005

Technologies of Lithium Ion Polymer Battery

Young Bae Roh

£-square Technologies

970-63, Wolchul-Dong, Buk-Gu, Gwangju-City, 500-460, Korea

Te/:+ 82-62-973-7041, Fax:+ 82-62-9 73-7045

E-mail: rybjok@e2-tek.con

Lithium Ion Battery(LIB) has been known to the general public as power source with

higher energy density, longer cycle life, larger capacity and smaller self-discharge than

those of commercial rechargeable batteries(Ni-MH, Ni-Cd and so on)[l -2]. Therefore,

lithium ion battery has been used widely in the 3C market such as Mobile phone,

Camcorder and Laptop since 1990's. Specially, Lithium Ion Polymer Batteries (LIPB)

are in spotlight in secondary battery market because it is very light but has higher

energy density than LIB and then is using the main power for Electric Vehicle (EV) in

recent.

Fig. 1 shows the technology tree of battery. LIPB is located in the top of battery

technology and is at the cutting edge of secondary battery technology.

Battery

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電気材料技術雑誌第14巻第2号J.Soc.Elect.Mat.Eng. Vol.14, No.2, 2005

Fig. 1. Battery Technology Tree

Fig. 2 explains about energy density comparison of several secondary batteries.

The vertical line represents gravimetric energy density which means to be able to make

battery light. LIPB system is to be lighter than other battery system. The horizontal line

represents energy density per volume which means to be able to make battery small.

LIPB system is to be smaller than other battery system. It is reasonable for LIPB

system to be selected as the most powerful source of the secondary battery system in

the world.

5

2 0

0

0

(W疋kg)Gravimet『icEnergy Density

20

15

10

e

如介且

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r

゜Capacito

5

゜~'II!'; 二 Smalle

゜10

Energy。(Wh/1)

20 30

Densit){) per 40

籾 lume゜5

0

Fig. 2. Energy density comparison of various secondary batteries.

Reaction mechanism of Li secondary battery is very simple as shown at the Fig. 3.

Li ion battery consists of a carbon anode and a cathode of Li metal compound (LiCo02).

Li metal is not in the battery. That means the safety of lithium ion battery is a good

theoretically if manufacturing default is not generated in.

Li ion in the crystal structure of lithium cobalt oxide (LiCo02) is only moving to the

Graphite layer during the discharge and then return to the cathode during the charging.

We call this mechanism as the rocking chair or shuttlecock [3-5].

Li ion battery systems are divided into four parts according to the types of anode

material or cathode material as shown at the Fig. 4. If liquid electrolyte and carbon

anode is used, the system is defined as the lithium ion battery. Li Ion polymer battery

system use carbon anode and polymer electrolyte.

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電気材料技術雑誌第 14巻第2号J.Soc.Elect.Mat.Eng. Vol.14, No.2, 2005

charge e-

-current collector

separator

+current collector

REACTION

● Positive electrode LiCo02手Li1-xCo02+ xLi+ + xe―

● Negative electrode

Cn + xLi+ + xe一手CnLix

● Overall discharge charge ~ LiCo02 + Cn d Li1-xCo02 + CnLix ．

Oxygen

． Metal Atom L゚ithium

． Carbon

Fig. 3. Reaction mechanism of lithium ion battery.

Li Metal Batte ry(LM B) Li-ion Battery(LIB)

LI Metal

~HighCi甲a叫y Liquid Electrolyte tong町C給Ufe ►

•· i.ow-Q四吐胆

、◄ 8$d High Rate Capa.

Polymer Electrolyte t.awt,a匹 ity,,

High CO$l to make . •

Carbon (Liーion)

Li Polymer Battery(LPB) Li-ion Polymer Battery(LIPB)

Fig. 4. Derivative systems of lithium ion battery.

Li Ion polymer battery has many advantages in aspects of battery performance,

comparing with lithium ion battery. LIPB is able to be thinner, lighter, cheaper and more

flexible design than LIB. Specially, a safety of LIPB is better than LIB so that LIPB

system is apt to use power source of Electric Vehicle and is popular to the high power

system to derive motor such as electric tools and R/C appliances.

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電気材料技術雑誌第 14巻第2号J.Soc.Elect.Mat.Eng. Vol.14, No.2, 2005

However, It is necessary for us to solve swelling problem to apply LIPE to

commercial electronic appliances. The swelling problem is to be main defect and

affects on the change of cell thickness as shown at the Fig. 5.

7.5

7.06

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---一--Max ---一— ·Min

5

0

5

6

6

5

(EE) ssau)I0!4l.

4.5

5.0 ... -------~ ---------------------------------------------------

Assembly Formation Charge Standard Charge 90'C, 6hr

E-Square Tech

Fig. 5. Cell thickness variation of LPB on the storage test condition under 90℃.

When the battery starts a redox reaction, gas is generally generated in the battery, the

exterior of the Li polymer battery is made of Aluminum laminated film (Pouch) instead

of aluminum can like lithium ion battery. The pouch is inclined to swell easily and to

make cell thickness changed due to weakness of material.

In facts, there are several factors influenced on swelling in battery system. A special

solution which prevents gas from being generated in the battery is added additive

material to electrolyte in the LIPB.

It has been paid close attention to search for functional electrolyte with additive

material. Functional electrolyte is designed to generate a dense film called solid

electrolyte interface (SEI) on the surface of carbon anode during the first charging

process. We expect functional electrolyte to protect a continuous gas evolution for the

cycle running. We calculated HOMO (highest occupied molecular orbital) and LUMO

(lowest unoccupied molecular orbital) level of additive materials like as much as 150EA

to select promising additive materials as shown at the Fig. 6.

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電気材料技術雑誌第 14巻第2号

J.Soc.Elect.Mat.Eng. Vol.14, No.2, 2005

-14

oxidation

resistance

゜ー

(＞

a) Ov'JOH

▲

-12

-8

-6

-3

Additive Selection

❖ physical property

❖ electrochemical

property

(LSV & CV)

❖ molecular structure

❖optimizing

molecular orbital

function (HOMO /

LUMO)

-2 -1 1 2

LUMO (eV) • ゜3

reduction

『esistance

Fig. 6. An extent of redox reaction on HOMO and RUMO value.

Fig. 7 shows variation of cyclic voltammetic profiles between general electrolyte and

functional electrolyte with additive material, SEI formation due to the decomposition of

functional electrolyte is appearing at the lower voltage than one of general electrolyte.

The research of quantitative and qualitative analysis on SEI film is now on progressing

in our laboratory.

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147 / [247]

電気材料技術雑誌第 14巻第2号

J.Soc.Elect.Mat.Eng. Vol.14, No.2, 2005

Fig. 7. Variation of cyclic volammetric profiles between general E/L and additive E/L.

Fig. 8 shows the effect of functional electrolyte. Test condition of cell is designed to

show clearly the change of cell thickness under 85℃ . Functional electrolyte decreases

effectively the cell thickness by 30% after 7 days, comparing with general electrolyte.

Swelling in terms of the change of initial thickness is controlled by 3% in the functional

electrolyte. SBACA (2-Sulfobenzoic acid cyclic anhydride) shows a good characteristic

to control cell thickness as the additive material in electrolyte.

SBACA is now in pending on international patent as the material of swelling restraint.

,40•,ti

l~-.-,,o

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25-,-i}

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01iJ:

Tm駈贔叫油4.JV~f.SCJ如—>iS℃碑叫切g知,~1血ル細

＇皿 .fllR IDAヽぞ 7DAY

匹 e

Fig. 8. Effect on swelling restraint under 85℃ standing for 4hrs, lday and 7days.

References

[l] Y.B. Roh, T. Kawai, H. Araki and K. Yoshino, Jpn. J. Appl. Phys, Vol. 33 (1994) 5917.

[2] N. Takami. A. Satoh. M. Hara and T. Ohsaki, J. Electrochem.Soc,142 (1995) 2564.

[3] Y.B. Roh, K.M. Jeong, H.G. Cho and H.Y. Kang, J. Power Sources, 68 (1997) 271.

[ 4] K. Sato, M. Noguchi, A. Demachi, N. Oki and M. Endo, Science, 264 (1994) 556.

[5] J.R. Dahn, T. Zheng, Y. Liu and J.S. Xue, Science, 270 (1995) 590.

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