additives, polymer binder, and current collector.

(1)

1

Batteries are inherently complex and virtually living systems - their electrochemistry and

transport processes vary not only during cycling but often also throughout their lifetime.

The performance of battery systems is limited by the performance of the constituent materials –

including active materials, electrolytes, separator,

additives, polymer binder, and current collector.

(2)

2

※ Source : 삼성 SDI 2008

Powertool

HEV, EV Robot

UPS House

풍력발전 태양발전

Energy Storage System Cleaner

HEV Pack System

Space Shuttle Airplane

E-Bike

Small batteries for mobile IT devices  Large cells for electric vehicles and energy storage

9.8조원

(소형 2차 전지) IT 시장

21.2조원

(중/대형 이차전지) 非 IT 시장

Battery markets

(3)

3

Secondary Batteries

→ Electricity storage and transportation Electric vehicles; storage and transportation Renewable generations (solar and wind) - Improve the electricity quality

- Electricity generation at remote area, - Electricity consumption at city area

Smart grid: DC transmission and DC distribution

(4)

4

자료 : IIT ’08.3

Tech Level

(100)

일 본

(95이상) 한

국 (50) 중

국 (30)

미 국 20

40 60 80

100 (100)

일

본

(50) 한 국

(40) 중 국

(40) 미 국

(100)

일 본

(30) 한 국

(10) 중국

(80)

미 국

Production Materials Core Tech

단위 : %

Market Share

0% 20% 40% 60% 80% 100%

'02 '03 '04 '05 '06 '07 '08

73 66 58 58 55 51 50

11 12 16

17 18 22 24

16 22 26

25 27 27 26

일본 한국 중국/기타

Korean Battery Industries

- Small batteries for mobile IT (mobile phones, NBPC) - No commercial batteries for EVs yet

- Competition for EVs batteries is wide open

(5)

5

Core Technologies ??

- Nature, Science papers ?

- New electrode materials: capacity, energy, power, safety, price, cell life

- Carbon additive, polymer binder, current collector, additives - Degradation analysis; Failure modes: cell life, safety

- Cell performances under abuse conditions - Accelerated rate test

- Diagnostic and prognostic tools - New battery systems

(6)

6

Battery Road Map for EVs (NEDO)

(7)

7

Goals and performances of EV cells

(USABC, 2009)

(8)

8

Specific energy : 150 Wh/kg (C/3) Energy density: 230 Wh/L (C/3) Production Price: 150 $/kWh

Operating Temperature: -40 ~ 50℃

Calendar life: 10 years Safety Characteristics Charging Time

The performances to be improved

(9)

9

350 300

250

200 400 450 550

1995 1994

1996

1998 2000

2001

Typ.1250mAh Typ.1370mAh

Typ.1420mAh

Typ.1700mAh

Typ.1900mAh

2002

4.2V Charging System

4.1V Charging System

Typ.2000mAh Typ.2100mAh

Typ.2200mAh

2003

Volumetric Energy Density (Wh/l)

Typ.2400mAh

500

18650 cells :

Capacity doubled for 10 years

Cell design

New electrode Materials !!

Energy density (capacity)

(10)

10

Prices

 Raw materials

- Expensive Co oxides → New materials with Mn, Fe, Si

 Materials Production

- Cheaper processes: simple step, facilities Nano materials ? Coating?

- Mass production

 Cell manufacturing - Automation

- Mass production

(11)

11

Operating Temperature

-40 ~ 50 ℃

High Temp: Cell degradation - Electrode, electrolyte

decomposition

- O₂ evolution from cathodes - Fire, explosion

Low Temp: Poor lithiation rate

- Li plating on graphite → safety problem - Inhomogeneous lithiation

→ electrode degradation → cell life

0 1 2 3 4 5 6

Voltage / V (vs. Li )

Electrochemical stability window of electrolytes

Electrolyte decomposition Electrolyte

decomposition

Li_xC₆

Li_xSi

Li_4+xTi₅O₁₂

Li_1-xMn₂O₄ Li_1-xCoO₂

Li_1-xNi_1/2Mn_3/2O₄

/Li+

Li_1-xFePO₄

Li plating

A

A B

Basal plane

Edge plane

Interplanar distance

(12)

12

- Electrolyte decomposition → passivation layer - Thermally and electrochemically unstable

- SEI formers (additives)

SEI (Solid Electrolyte Interphase)

0 1 2 3 4 5 6

decomposition

LixC6

LixSi

Li4+xTi5O12

Li1-xMn2O4 Li1-xCoO2

/Li+

Li_1-xFePO₄

Li plating

(13)

13 0

1 2 3 4 5 6

decomposition

LixC6

Li_xSi

Li_4+xTi₅O₁₂

Li1-xMn2O4 Li_1-xCoO₂

/Li+

Li1-xFePO4

Li plating

Fast charging

Charging voltage = E_cell + η_a + η_c + iR_total

At high current → Li plating, electrolyte decomposition → Safety, cell life

(14)

14

Future Battery Industries

발전소 변압기

배전변전소

신재생에너지 저장장치

휴대용 IT 기기

로봇 및 파워툴

수송기계용 UPS 대규모전력저장

(15)

15

New battery systems for EVs

Cells Lead-

acid Ni-MH Li ion

(present) Li ion

(maximum ?) ??

Specific energy

(Wh/kg) 30 80 150 250 500

Weight

(kg) 3000 1125 600 360 180

(EV; 90 kWh for 500 km driving)

Metal-air secondary cells (Zn-air, Li –air)

Li-S secondary cells

(16)

16

Lithium-sulfur secondary cells

Higher gravimetric energy density

Low cost- $0.57/kg (Cobalt oxide: $44/kg) Comparable volumetric energy density

Sulfur: poor electrical and ionic conductivity Shuttle mechanism by soluble polysulfides S₈ → Li₂S₈→ Li₂S₄→ Li₂S₂→ Li₂S (Soluble) (Insoluble)

Energy density – Wh/kg

(17)

17

Theoretical energy density

(18)

18

Sulfur electrode

(19)

19

Li-air cells

(20)

20

Protected lithium electrodes

(21)

21

(22)

22

Requirements for battery commercialization

9) Energy efficiency:

- Energy (Q x V) required for charging/energy recovered by discharging

- Important for energy storage batteries

- Coulombic efficiency (Q) - Voltaic efficiency (V)

Li / air secondary cell

Discharge

Charge

(23)

23

Supercapacitors

Supercapacitors Ultracapacitors

Electrochemical capacitors

- Electric double-layer

capacitors (전기 이중층 커

패시터)

- Pseudo-capacitors (유사 커패

시터)

Ragone plot

(24)

24

Electric double-layer capacitors

FeCp

₂⁺  Faradaic current

 Non-faradaic current

Equivalent circuit (등가회로)

(25)

25

1) EDLC에서 double-layer charging current; i

_C

= C

_dl

v

2) 전극 표면에 흡착 또는 확산이 필요 없는 표면 반응;

i

_f

∝ ν (surface reactions)

3) Faradaic reactions near surface RuO

₂

+ H

⁺

+ e = H

_x

RuO

₂

i

_f

∝

_ν^1/2

(diffusion-controlled)

Pseudo-capacitors

1) Faradaic current; O + ne = R

2) Non-faradaic current; double-layer charging current

(26)

26

CV for diffused species

(27)

27

Cyclic voltammogram for adsorbed species

(28)

28

Electric double-layer capacitors

Symmetric EDLC

Capacitive de-ionization

- - - - - - -

+ + + + + + +

- ion + ion

Electrode Current collector

+ -

+ + + + + +

+

+ + +

+ +

- -

- - -

- -

-

- -

(29)

29

Charge/discharge voltage profile

0.0 1.0 2.0

Time / s

100 300 500

0

Voltage / V

3.0

C 1 =

Q (= it) V

Charging Discharging

(30)

30

Capacitance of supercapacitors

(31)

31 31

capacitor electrode

Hybrid capacitors

battery electrode