Electrode Architectures for High power
density Li-ion batteries
Electrode Architecture
Electrochemical Testing
2
1.0
8
0.8
6
0.6
4
0.4
2
One, 2.4 mg/cm
2
Four, 8.93 mg/cm
2
Std, 2.76 mg/cm
120
Discharge Capacity (mAh/g)
2
Discharge Capacity
Active Material Loading
100
80
60
40
20
2
Discharge Capacity (mAh/cm )
Active Material Loading (mg/cm )
10
0
1
2
3
4
Number of Active Material Layers
0.2
0
0
10
20
30
40
C-Rate
Uniform Increase in loading Had minimal impact on the C‐rate 50
Effect of Electrode composition
120
2
S td, 10% carbon 1.85 m g /cm
2
S td, 20% carbon 2.76 m g /cm
2
4 Laye r, 10% carbon 7.19 m g/cm
2
4 Laye r, 20% carbon 6.18 m g/cm
Discharge Capacity (mAh/g)
100
80
60
40
20
0
0
2
4
6
8
10
12
C -rate
14
16
18
20
22
With low rate material
Layered‐ layered Oxide active material 250
Discharge Capacity (mAh/g)
4 Layer, 9.1 mg/cm
2
Std, 6.5 mg/cm
2
2
Power Output (mW/cm )
12
9
6
3
0
2
4
6
8
10
2
Energy Output (mWh/cm )
12
2
4 Layer, 9.1 mg/cm
C/20
200
C/20
C/20
150
1C
1C
100
1C
50
0
0
100
200
300
Cycle Number
400
500
Comparision
Energy Harvesting from
Infrared Sources
Need
 Needs a continuous source of energy for
various electronics, communication and
sensing devices.
 Need to carry less heavy batteries and
reduce the warfighter’s load.
 Other energy harvesters are either heavy or
cannot provide the needed power.
Modern day smart soldier
 Thin film organic photovoltaic cannot
provide power in the absence of sunlight
(e.g. nighttime cloudy days etc.).
 A light weight flexible device capable of harvesting
energy continuously and producing enough power to
properly power various portable devices.
Objectives & Advantages
Objectives:
• To harvest energy at any time even
in the absence of sunlight.
• To harvest energy from any heat
source
• To harvest energy from sunlight
complementing solar cells.
Sources of infra red
Daytime sunlight
Advantages:
•
•
•
•
Extremely lightweight
Flexible
Easily incorporated into fabrics
Low manufacturing cost
Human Body
Manmade
Application:
•
•
•
Remote operations
Emergency situations
Stand alone operations
Microprocessor
Vegetation Nighttime
Infra red Antenna – Barriers
Antenna:
 Excellent resonance (>80%) in the desired
frequency range (300GHz-450THz )
 Choice of materials need to exhibit very low
electronic transition when coupling to the incident
photon (reduced loss)
 Needs Nano-micro scale features to address the
desired frequency range
 Low electron phonon coupling (low heat generated)
Rectifier circuit:
 Needed diodes operating in the 300GHz-450THz range with efficiency >80%
 There are no diodes available commercially in that range.
 Research efforts are very limited.
 Low cost manufacturing method to address cost effectiveness.
Coupling circuit:
 Needed to have ~90% coupling efficiency.
 Current couplers have not been tested in the desired frequency range
How Does it Compare with Thermoelectric Harvester
Using diodes with theoretical limit
(80% efficiency)
100
90
Rectenna
80
Power generated (W/m2)
Using diodes in research
( 30% efficiency)
Thermoelectric
Series3
70
Using commercially available W
band diodes(10% efficiency)
Series4
60
Thermoelctric
50
40
30
Assumptions:
20
10
0
0
10
20
30
40
50
60
Temperature Difference (C)
70




Sink is at room temperature
(20 C)
Area of coverage for the rectenna: 60%
Area of coverage for the Thermoelectric: 100%
 Load resistance: 250 Ohms
Design & Simulation
Antenna Fabrication
Fluidic assembly is employed
Testing with Commercial W band (30GHz) diodes
Circuit employed
Testing setup
 Energy harvested was several hundreds of Nano watts