Electrode Architectures for High power density Li-ion batteries - PowerPoint PPT Presentation

Electrode Architectures for High power density Li-ion batteries

Electrode Architecture

Electrochemical Testing 10 2 One, 2.4 mg/cm Discharge Capacity 120 2 1.0 Four, 8.93 mg/cm Active Material Loading 2 ) 2 Active Material Loading (mg/cm Discharge Capacity (mAh/cm Std, 2.76 mg/cm 8 Discharge Capacity (mAh/g) 100 0.8 80 6 60 0.6 4 40 0.4 2 20 2 ) 0 0 0.2 1 2 3 4 0 10 20 30 40 50 Number of Active Material Layers C-Rate Uniform Increase in loading  Had minimal impact on the C ‐ rate

Effect of Electrode composition 120 2 Std, 10% carbon 1.85 mg/cm 2 Std, 20% carbon 2.76 mg/cm 100 2 4 Layer, 10% carbon 7.19 mg/cm 2 Discharge Capacity (mAh/g) 4 Layer, 20% carbon 6.18 mg/cm 80 60 40 20 0 0 2 4 6 8 10 12 14 16 18 20 22 C-rate

With low rate material Layered ‐ layered Oxide active material 250 2 4 Layer, 9.1 mg/cm 12 2 4 Layer, 9.1 mg/cm Discharge Capacity (mAh/g) C/20 2 Std, 6.5 mg/cm 200 C/20 2 ) C/20 Power Output (mW/cm 9 150 1C 6 1C 1C 100 3 50 0 0 100 200 300 400 500 0 2 4 6 8 10 12 Cycle Number 2 ) Energy Output (mWh/cm

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.  Thin film organic photovoltaic cannot provide power in the absence of sunlight (e.g. nighttime cloudy days etc.). Modern day smart soldier  A light weight flexible device capable of harvesting energy continuously and producing enough power to properly power various portable devices.

Objectives & Advantages Objectives: Sources of infra red • 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. Daytime sunlight Advantages: • Extremely lightweight • Flexible Human Body • Easily incorporated into fabrics • Manmade Low manufacturing cost 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 Using diodes in research Thermoelectric ( 30% efficiency) Rectenna 80 Power generated (W/m 2 ) Series3 Using commercially available W 70 Series4 band diodes(10% efficiency) 60 Thermoelctric 50 40 30 Assumptions: 20  Sink is at room temperature 10  (20 C)  Area of coverage for the rectenna: 60% 0  Area of coverage for the Thermo- 0 10 20 30 40 50 60 70 electric: 100% Temperature Difference (C)  Load resistance: 250 Ohms

Design & Simulation

Antenna Fabrication Fluidic assembly is employed

Testing with Commercial W band (30GHz) diodes Testing setup Circuit employed  Energy harvested was several hundreds of Nano watts