msepostdoc-list Seminar Notice for Daw Gen Lim Ph.D. Final Exam: Seminar Thursday, April 12, in HAMP 1252; Exam 3:30, same day, in ARMS 2237

[Son, Rosemary E]

Please consider attending the following:

MATERIALS ENGINEERING
SEMINAR


“Investigation of Electrochemically Li-ion Active Materials for Li-ion Batteries”

By
Daw Gen Lim
Purdue MSE Ph.D. Final Exam

Advisors: Professor Jeffrey P. Youngblood and Professor Vilas G. Pol

ABSTRACT

Being the battery of the 21st century, Li-ion batteries have been making headway towards replacing traditional medium to large scale energy storage devices. Recent applications ranging from EVs to grid-level energy storage, have driven the design criteria of Li-ion batteries to evolve at a rapid pace. Three major goals are low cost, high electrochemical performance, and better safety. New targets set by the DOE to make Li-ion batteries more competitive in their new market sectors have been to decrease cost to $125 kWh-1 and increase specific gravimetric and volumetric energy density to 235 Wh kg-1, 500 Wh L-1, respectively. Keeping the overall theme of low-cost, high energy density, and improved safety. This thesis presents works on the three major components of a Li-ion battery: sustainable wheat derived-carbon anodes, high capacity V2O5|Graphene nanoplatelets composite cathodes, and rare earth nickelates as a potential solid-state electrolyte for improved safety.
Systematic solid-state processing, structural, and electrochemical studies were conducted on wheat derived carbons. Coupling carbonization temperatures and structural evolution of biomass-derived carbons (in this case wheat), lithium insertion properties can be tuned, to create a high capacity and sustainable anode material. An optimal condition presents itself at a carbonization temperature of 600 ˚C with a stable lithiation capacity of 390 mAh g-1.
In the Li-ion cell, the limiting factor in the total output capacity (mAh g-1) of the cell is governed mainly by the cathode materials, as cathode materials tend to be lithium-based transitional metal oxides (high density compared to anode materials). Having one of the highest lithium storage capacity, V2O5 is a cathode material that suffers from low electronic conductivity and particle fragmentation upon continuous lithium insertion and extraction. In this work, sonochemistry is utilized in the synthesis of V2O5|Graphene-nanoplatelets (GNPs) composite to improve electronic conductivity and kinetics of lithium-insertion and extraction. Surface modification of the graphene nanoplatelets during sonication of GNPs allow for in situ growth of V2O5 nanoparticles. With the size reduction of the V2O5 particles and the conductive GNPs backbone, the composites achieved 248 mAh g-1 specific cathode capacity; retaining 83% of initial capacity after 50 cycles.
The previous two works illustrate strategies to create a low-cost and high electrochemical performance Li-ion battery via sustainable material implementation, structural and morphology control, and composite formation; this final work studies the electrochemical properties of perovskite rare-earth nickelates (specifically SmNiO3) and its integration as a solid-state electrolyte in an all-solid-state lithium-ion battery. Upon insertion of Li+ ion, SmNiO3 undergoes a Mott-transition, simultaneously allowing for a large amount of mobile Li+ to be stored at the interstitial sites (approaching a ratio of one dopant per unit-cell). The combination of a lattice expansion (~10% increase) and the interstitial doping creates a perfect condition for fast Li+ conduction with reduced activation energy. Initial efforts for the integration of the LiSmNiO3 in a solid-state-cell LiCoO2 |LiSmNi|Si results with initial charging capacities reaching 1338 mAh g-1.


Date: Thursday, April 12, 2018

Time: 2:30 P.M.
Place: HAMP 1252

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