Miniature power sources such as solid state batteries, super capacitors, and nuclear batteries are emerging technologies that can power devices for the Internet of Things and autonomous systems. Solid state batteries offer high charge density, safety, and long life in a miniature package, but have limited capacity. Super capacitors provide virtually unlimited cycling but have limited energy storage. Nuclear batteries using radioactive isotopes can power devices for 10-20 years but have low power output. Emerging technologies for miniature power sources will enable further implementation of autonomous wireless devices and sensors.

1. May 9, 2016
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Miniature power sources -
emerging technologies for powering IoT
and autonomous systems
May 9, 2016
Tuvia Liran
Nano Retina Ltd.

2. May 9, 2016
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Outline
• Available miniature power sources
• Categorizing batteries
• Solid State Battery
• Super capacitors
• Nuclear batteries
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The need for miniature batteries
• Wireless sensors (IoT)
• Remote controllers & RTC
• Implantable medical devices
• Watches
• Under water systems
• Active smart cards
• RFID
• Memory backup
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Definition of miniature batteries
• Batteries that can be assembled with ASICs, without
significant increase of package size
• Typical characteristics:
– Area – <200mm2
– Thickness - <<1mm
– Weight - <100mg
– Assembly – wirebond/bumping/soldering
– Low loss
– Long cycle life / many re-charging cycles
– Compatibility – RoHS compliant, low outgassing,
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Categorizing battery technologies
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Solid state
Rechargeable
Fuel cells
Non-rechargeable

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Energy harvesting technologies
• Energies that might be harvested
• Optical energy is the most effective
• DC-DC or AC-DC converters degrades efficiency
• Energy should be stored in battery/capacitor
Energy Source Device DC/AC
Optical/EM Light, IR,EM Photovoltaic, antenna DC
Kinetic Wind, motion,
vibration, hydro
Turbine, piezoelectric, MEMS, AC
Temperature Temp gradient Temp sensors DC
Biochemical Glucose, etc. DC

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Power of portable applications
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Comparing battery technologies
• Total power
• Specific energy (Wh/g)
• Energy density (Wh/l)
• Shelf life
• Life cycle / re-charge
• Charging rate
• Cost per Wh
• Safety
• Environmental conditions
• Operation temperature
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Solid state batteries (SSB)
• Re-chargeable
• Li PON dielectric (Li ion)
• Voltage: 3-4V
• Capacity: <1mAh
• Very high charge density
• Miniature
• Safe
• Eco friendly
• Long life
• Wide temperature range
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SSB packaging solutions
• Bare die + bondwire/bumps
• Packaged w RTC/PM
• Stacked
• MCM
• SMD
• Flexible (some vendors)
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Examples of miniature applications
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1mm3 Intraocular Pressure Monitor
Medical patches

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Cymbet/enerchip
• Silicon substrate
• Die/package
• Bondable
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Silicon die Packaged with power
management die

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Front edge
technology/NanoEnergy®
•50u thick
•Stackable
•Flexible
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Ultra thin
As thin as 0.05 mm (0.002 inch) including
package.
Safe &
environmentally
friendly
All solid-state, using ceramic electrolyte LiPON
developed by Oak Ridge National Laboratories.
Contains no liquid or environmental hazardous
material.
Long cycle life
More than 1, 000 cycles at 100% depth
discharge.
High current charge
Can be charged to 70% of rated capacity in 2
minutes.
High current
discharge
Can be discharged at rates of more than 10 C.
Flexible form factor Can be made into different shapes and sizes.
Low self-discharge Less than 5% per year.
Bendable Can be bent and twisted without damage.

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Other SSB vendors
• Johnson Battery Technology
• Excellatron Solid state
• Bellcore
• Infinite Power Solutions
• Planar Energy
• Honeycomb Battery (Israel)
• …..
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Power management for SSB
• Charger/DC-DC converter for charging
• LDO/DC-DC converter for discharge
• Over-voltage protection during charging
• Under-voltage protection during discharging
• Charge monitor
Power management devices
are available
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Super capacitor
• Key advantages WRT SSB
– Virtually unlimited cycle life
– Fast charging
– Simple charging to any voltage
– Safe - forgiving if abused
• Key limitations WRT SSB
– Limited capacity
– Linear discharge voltage
– High self-discharge
– Higher cost per watt

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Nuclear batteries
• Concept – photovoltaic
that is stimulated by
nuclear sources:
– Alphavoltaics
– Betavoltaics
– Gamavoltavics
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Betavoltaics Tritium battery
• Tritium = 3H (isotope of Helium)
• Available from nuclear waste
• Radioactive – half life is 12.3 years
• Decay equation (e- = 18.6KeV)
• e- converted to energy by photovoltaic
• Compounded in tritides (titanium, scandium)
• Power - <<1uW
• Lifetime – 10÷20 years
• Safety – considerable for medical
• Prices – hundreds of USD
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Applications of Tritium batteries
• Environmental pressure/temperature sensors
• Intelligence sensors
• Medical implants
• Semi-passive and active RFIDs
• Silicon clocks
• SRAM memory backup
• Deep-sea oil well sensors
• …
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Summary
• Miniature batteries are available
• Implementing autonomous systems is doable
• High improvement rate in all types of battery
technologies
• Optimal implementation includes:
– Efficient battery
– Ultra low power system
– Battery management
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