PhD Thesis Proposal: Baiheng Li

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Meeting ID: 995 3925 5283
Passcode: 461933

"Materials design and optimization for sodium-based solid-state batteries"

Abstract

Sodium-ion batteries (SIBs) are a promising candidate for next-generation energy storage solutions, especially in the case of grid energy storage applications due to raw material cost and availability for cathode, anode, and electrolyte materials. In addition, sodium (Na)’s similarity to lithium (Li) in terms of physicochemical and electrochemical properties is favorable for the design and development of SIBs with the convenient reference of current lithium-ion batteries (LIBs). However, many challenges remain to be resolved in order to harness sodium’s much higher chemical reactivity comparing to lithium: for example, the cycle life and safety of SIBs leave a lot to be desired. To eliminate excessive side reactions between the electrodes and electrolyte in SIBs, one advantageous approach is the employment of solid-state electrolyte (SE). 
 
NASICON (Na_1+xZr₂Si_xP_3−xO₁₂) is a type of ceramic SE that has exceptional chemical stability when in direct contact with metallic Na, wide electrochemical voltage window, and fabrication methods that can potentially become scalable, which makes it a good option for Na solid-state batteries (SSBs). While it helps to harness sodium metal’s reactivity and thus resolves previously mentioned associated issues, the electrode-electrolyte interface suffers from poor wetting due to the material properties. In this thesis, a grain boundary engineering strategy that targets the electrode-electrolyte contact issue and improves the ionic conductivity of NASICON electrolyte was thoroughly studied. As a result, a stable Na SSB with metallic Na anode was designed with proven cycle life of over 10,000 h. Additionally, the effect of process control agents (PCAs) in the fabrication process of NASICON SE was systematically evaluated. With the optimized PCA concentration, the fabrication time can be shortened significantly with uncompromised physical and electrochemical properties in the final SE. In summary, this thesis aims to bring Na SSBs closer to practical applications by making improvements both in electrochemical performance and scalability of production.

Thesis Committee

• Weiyang Li (Chair)
• Ian Baker, Jifeng Liu

Contact

For more information, contact Thayer Registrar at thayer.registrar@dartmouth.edu .