1. Development of Lithium Batteries for Powering Sensor Arrays
SFR Workshop
May 24, 2001
Nelson Chong, James Lim, Jeff Sakamoto
and Bruce Dunn
Los Angeles, CA
2001 GOAL: (a) to develop thermally robust inorganic electrolyte;
(b) incorporate silicon lid into battery encapsulation scheme
by 9/30/2001.
5/24/2001

2. Major Components of a Lithium Battery
5/24/2001

3. Project Direction In order to power SMART wafers, a low profile,
thermally stable,
high energy density
battery must
be used.
Lithium-V2O5 thick film batteries are used to power SMART wafers.
Advanced fabrication and encapsulation methods are needed to enhance battery performance under vacuum and high temperature conditions.
5/24/2001

4. New Inorganic/Organic Electrolyte
72.5 wt.% 0.9 M Li Imide LiN(CF3SO2)2
in propylene carbonate
21.7 wt.% PMMA
Fumed Silica R805
particles/aggregates
5.8 wt.% (12nm)
Silica Network in
PMMA framework
van der Waals
electrostatic interactions
hydrogen bonding
Mixed by hand
and heated oC
10 – 15 mins
Li+ conduction
Interconnected pore
network provides a
continuous ionic path.
Fumed Silica
Colloidal particles added to improve mechanical and thermal stability.
Thermal stability >125 oC
5/24/2001

5. Improved Electrolyte Thermal Stability and Electrochemical Stability
Stable thermal cycling
between room temperature
and 125oC.
Stability window exists
between 2.5 and 4.0 volts.
Peaks are associated with
stainless steel characteristics.
Well behaved conductivity
characteristics to > 125oC
5/24/2001

6. Thermal Cycling Characteristics of Battery with Nanocomposite Electrolyte
Thermal tests at lower current density
operation at 125oC
cycling between RT and 125oC
Batteries discharge nicely at
125oC. No capacity loss when
alternate between RT and 125oC.
5/24/2001

7. Battery Encapsulated with Silicon Lid
Discharge Characteristics for
Silicon Lid Attached Battery
2mA discharge
5/24/2001

8. Lid Attachment Using Plasma Assisted Bonding (with N. Cheung)
5/24/2001

9. 2002 and 2003 Goals
2002 Integrate new electrolyte into battery structure Develop in-situ lithium formation process
2003 Battery operation between RT and 150oC Battery survivability to sensor soldering operation
5/24/2001