1. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. AS deposited LiCoO 2 thin film cathodes prepared by RF magnetron sputtering AS deposited LiCoO 2 thin film cathodes prepared by RF magnetron sputtering Shin-Wook Jeon, Jeong-Kyu Lim Duck-Sik Park, Sung-Man Lee Department of Advanced Material Science and Engineering, Kangwon National University, Chuncheon, Kangwondo, 200-701, South Korea E-mail : shinwook79 @ hanmail. net

2. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. 전지 구성요소를 박막화하여 초소형화시킨 고상의 박막 전지 (Solid state thin-film battery) 전자 기기의 chip 초소형 기기 및 소자의 전원 Discharge Charge Li + ion - + 전해질양극 음극 기판 양극 음극 전해질 하부콜렉터 상부콜렉터 고상박막전지집적회로 IC 카드  m  Thin Film Microbattery : Concept

3. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. Thin Film Microbattery : Application Microbattery-based technology in the 21 st century Micro Battery MEMS Microelectronics Power Implantable Device 의료 바이오 칩 수술용 로봇 투약 시스템 내시경 인공 장기 정밀기계 마이크로 로봇 초소형 무인정찰 비행기 마이크로 액추에이터 마이크로 센서 마이크로 모터 전자 보안카드 독성카드 방사능 감지카드 GPS On-chip 배터리 정보통신 마이크로 PDA 스마트 카드 카드형 컴퓨터 마이크로 산업 발전 Micro Power System 마이크로 산업 발전 Micro Power System Power Implantable Device ( 소자 + 구동회로 + 전원 = 일체화 ) Power Implantable Device ( 소자 + 구동회로 + 전원 = 일체화 )

4. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. Crystalline LiCoO 2 High specific capacity, high operating voltage. Deposition at an elevated temperature. or Post – annealing treatment at high temperature. Thermally induced micro-cracks. Low temperature substrate (ex. Flexible polymer material) 사용제한 Background

5. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. Experimental - 2 inch target - Cold press - Sintering : 900 ℃ for 2hr - RF magnetron sputtering Thin Film deposition - XRD - α -step - Raman - FE-SEM - TEM Analysis Target synthesis Film deposition condition Process parametersConditions Base pressure 2×10 - 6 Torr Working pressure 5 ×10 - 3 Torr Gas flow rate Ar: 45 sccm, O 2 : 5 sccm RF power 50 – 150 W Sub. to target 7 cm Substrate cooling O Film thickness 6,000 – 17,000 Å Electrochemical test Cell type 2016 coin cell Counter electrode Lithium foil Electrolyte 1M LiPF 6 in EC:DEC=1:1 Cut off - Voltage 3.0 - 4.2V / 3.0 – 4.0V Current density 30 ~ 500 ㎂ /cm 2

6. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. As – deposited LiCoO 2 films XRD Raman spectra Sputtering rf power : (b) 50 W, (c) 100 W, (d) 150 W (a) Substrate (stainless steel)

7. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. Plan–View HREM (Deposition at 150 W) Diffraction pattern As – deposited LiCoO 2 films

8. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. Substrate temperature during deposition at different rf powers As – deposited LiCoO 2 films

9. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. Charge-discharge curve Differential capacity plot As – deposited LiCoO 2 films

10. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. Cyclability (3.0 and 4.0 V) As – deposited LiCoO 2 films Cyclability (3.0 and 4.2 V)

11. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. Discharge capacity vs. film thickness (deposition at 150 W) As – deposited LiCoO 2 films Amount of cobalt dissolution (in the electrolyte)

12. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. Constant Current discharge Curve (film thickness:1.34 um, deposition at 150 W) Normalized capacity vs. current density As – deposited LiCoO 2 films

13. Thin Film & Battery Materials Lab. National Research Lab. Kangwon Nat’l Univ. Conclusion The as-deposited films have (101) and (104) preferred orientation and their crystallinity increases with increasing rf power during sputter deposition ( As-deposited LiCoO2 thin films confirmed nano-crystlline structure by XRD, Raman and TEM study) As a result of the texturing, the cell using the as-deposited LiCoO2 cathode showed a relatively large discharge capacity of ∼ 59 ㎂ h/cm2· ㎛ on cycling between 4.2 - 3.0 V. These results suggest that as-deposited LiCoO2 films with a nanocrystalline structure and a favorable preferred orientation, i.e., (101) or (104) texture, can be used for the fabrication of thin-film microbatteries without post-annealing process.