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Increased Capacity Retention of Silicon Anodes for Lithium Batteries

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: The objective of this topic is to develop advanced silicon anode cells with increased capacity retention, coulombic efficiency, and electronic conductivity. 

DESCRIPTION: The U.S. Army TRADOC has identified a need for reliable, high-energy power sources to support soldier, squad, and platoon operational requirements, especially in austere environments where power source availability is limited. The integration of silicon anodes, with their high theoretical specific capacity (4.2 Ah/g), into cells and subsequent battery packs will assist in extending mission endurance in support of dominating the electromagnetic spectrum, commanding the operation, and more directly enabling decisive effects. The introduction of silicon as an anode in lithium-ion rechargeable batteries can greatly increase their energy density, especially in comparison to carbon. However, silicon is plagued by poor capacity retention as a result of the volume expansion that occurs during lithiation and delithiation while cycling. This volume expansion results in particle fractures across the anode. Anode fracturing will then have a detrimental effect on the cell’s capacity, capacity retention, coulombic efficiency, and performance at high rates. This topic desires to mitigate or eliminate some of these detrimental effects in order to improve capacity retention and coulombic efficiency. Target cell-level requirements include a high specific capacity of 750 mAh/g with at least 25 wt% silicon content, capacity retention of 224 cycles to 80% original capacity at a rate of 1 mA/cm2. Cells must be able to operate from -30 °C to 55 °C. Developmental cells must also demonstrate the ability to handle high rate loads effectively, with minimal impact to capacity. Prototype cells must deliver at least 400 Wh/kg at the cell level, targeting 300-600 Wh/kg at the battery level. The final battery shall weigh less than or equal to 2.6 lbs. 

PHASE I: Explore and define cell materials or half cells demonstrating improvements that mitigate or eliminate detrimental effects of Si anodes in order to improve electrochemical performance. Demonstrate pathway for reaching target requirements outlined in this topic. 

PHASE II: Refine and optimize materials chosen in Phase I and develop prototype pouch cells to meet target performance requirements in the specified temperature range outlined in this topic. 

PHASE III: Transition technology to the U.S. Army. Integrate this technology into portable consumer or military devices that require high energy density power sources. 

REFERENCES: 

1: Chief of Staff of the Army Priority #1

2:  Army Warfighter Challenge #16

3:  Xiuxia Zuo, Jin Zhu, Peter Müller-Buschbaum, Ya-Jun Cheng. "Silicon based lithium-ion battery anodes: A chronicle perspective review." Nano Energy, Volume 31, January 2017, Pages 113-143.

4:  François Ozanam, Michel Rosso. "Silicon as anode material for Li-ion batteries." Materials Science and Engineering: B, Volume 213, November 2016, Pages 2-11

5:  Choa Kim, Deepak Verma, Dong Ho Nam, Wonyoung Chang, Jaehoon Kim. "Conformal carbon layer coating on well-dispersed Si nanoparticles on graphene oxide and the enhanced electrochemical performance." Journal of Industrial and Engineering Chemistry, Volume 52, August 2017, Pages 260-269.

KEYWORDS: Silicon Anode, Rechargeable, Lithium Batteries, Capacity Retention, Coulombic Efficiency, Dismounted Soldier Power 

CONTACT(S): 

Dr. Ashley Ruth 

(443) 395-4386 

ashley.l.ruth2.civ@mail.mil 

Paula LaTorre 

(443) 395-4676 

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