|Sion Power’s EV Battery
400 Watt-hours per kilogram is a long-awaited minimum expectation for what it will take to get electric aviation off the ground. Sion Power® of Tucson, Arizona will introduce its Licerion® 17 Amp-hour pouch cells at the Battery Show North America in September – claiming to fulfill that expectation. The large-format pouch cells come in a compact 810 Watt-hours per liter size, last over 800 cycles and can be charged to 80-percent of their rated capacity in 15 minutes, according to Sion.
Sion Power is shifting from its lithium-sulfur chemistry to lithium-metal technology. Their Li-S cells powered Airbus’ Zephyr® 7 HAPS (High Altitude Pseudo Satellite) to a record for continuous flight. According to Tucson Tech, “In 2014, lithium-sulfur batteries custom-made by Sion helped power Airbus’ Zephyr 7 solar-electric unmanned plane to fly for 11 days on sun power during the day and battery power at night.”
From Lithium-Sulfur to Licerion®
In a paper on the subject, Sion Power explains its change from lithium-sulfur to its current approach. “However, even with this success, Sion Power was aware of an intrinsic weakness with Li-S that limited its usefulness for most applications. In 2015, Sion Power began research and development work on its next-generation rechargeable cell that overcame the limitations of Li-S.
Sion has created three levels of protection for safe storage of energy, as reported in GreenCarCongress.com.
· At the cell-level, electrolyte additives chemically stabilize the anode surface to enhance cycle life and increase energy. The cells do use a liquid electrolyte; however, the amount is negligible compared to traditional Li-ion cells.
· The lithium metal anode is physically protected by a thin, chemically stable, and ionically conductive ceramic polymer barrier.
· The pack incorporates proprietary cell compression and an advanced battery management system (BMS).
Licerion battery packs include many safety features and an intelligent battery management system.
Using Licerion cells, Sion Power’s modular design simplifies connection and configuration of battery packs “for a wide variety of applications.” The battery management system (BMS) includes cell balancing, discharge circuit control, state of charge (SoC), and state of health (SoH) estimation, and CAN 2.0 communication.
Standard safety features include Sion Power’s cell compression system, probably similar to other such systems that physically compress pouch cells for improved performance. Electrical safety measures include over-charge and over-discharge protection, over-temperature protection, and over-current protection. Each module is equipped with fuses and switches, and custom containment enclosures are available.
It will be of interest to see if Sion Power or Northvolt come to market with their battery systems soon, and how soon we will see them in actual EVs, including aircraft. Fully available batteries at reasonable prices and with high levels of safety are essential to the future of electric flight.