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High Energy, High Power 5V Electrochemical Energy Storage Solution

Description:

TECHNOLOGY AREA(S): Electronics, 

OBJECTIVE: The objective of this topic is to develop an electrochemical cell capable of 5.0 V operation without capacity fade to support high power/energy demand of situational awareness devices in support of the Soldier Lethality Cross Functional Team (CFT). 

DESCRIPTION: Lithium-ion batteries are a ubiquitous solution for portable energy storage for military applications. Their high energy density and recharge-ability at a reasonable cost make them very attractive for use in portable systems such as the centralized power source on the Next Generation Squad Weapon or on the Warfighter to enable the Integrated Visual Augmentation System. However, this chemistry is presently limited to lower voltage operation due to the voltage stability of the cell-level components. Traditional lithium-ion batteries utilize carbonate-based organic electrolytes that degrade at elevated voltages above 4.4 V that result in CO¬2 generation, increased cell impedance, and active material consumption which prevent longevity of the cell. Other liquid electrolyte systems with high voltage stability often fail to achieve a suitable anode SEI (solid electrolyte interphase) to allow for continued cycling without capacity fade. In addition to electrolyte limitations, because selected anode potentials are often already close to the potential of lithium, the voltage of the cell is primarily dictated by cathode potential. Therefore, selection of a suitable cathode is critical to achieving the high voltage targeted by this topic. The C5ISR Center is interested in a cell system of electrolyte and electrodes that yield a high energy, high power 5 V electrochemical energy storage solution. Such a solution will directly apply to Soldier Lethality systems but can be leveraged to meet the demands of the Integrated Tactical Network, radio batteries, or incorporated into a storage component for pulsed power applications. The resultant cell chemistry must perform across a wide temperature range between -30°C and 60°C. The cell must target a specific energy density greater than 400 Wh/kg at C/5 rate or 300 Wh/kg at a 5C rate at the cell level in order to achieve high performance at a battery level. Cell chemistry must demonstrate < 2% irreversible loss (on 3rd cycle at C/5) after 1 month of storage fully charged at 55°C. Considerations must be made to optimize cell efficiency to prevent wasteful charging conditions. The resultant cell must achieve 50% of capacity at -20 °C at C/10 rate. 

PHASE I: Investigate various electrolyte/electrode systems to optimize the electrochemical performance at operating voltages at or above 5.0 V. Demonstrate high voltage operation with greater than 150 cycles in a laboratory cell and begin testing across a range of temperatures between -30°C and 60°C with emphasis on low temperature performance. Deliver 10 representative laboratory coin or single-layer pouch cells to C5ISR Center for preliminary electrochemical performance testing. 

PHASE II: Refine and optimize the cell-level materials selected in Phase I and develop and deliver prototype cylindrical cells or multi-layer pouch cells to meet target performance requirements in the specified temperature range with rate capability outlined in this topic. 

PHASE III: Transition technology to the U.S. Army for packing into a battery system in appropriate physical and electronic configuration. Integrate this technology into portable military devices that require high energy density power sources. Alternatively, integrate this technology into an energy storage component for pulse power applications. 

REFERENCES: 

1: Chief of Staff of the Army Priority #1

KEYWORDS: Energy Storage, High Energy, Portable Power, High Power, Pulse Power, Soldier Lethality, Future Vertical Lift 

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