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Fundamental study of engineered cathode and Li-ion conducting electrolyte architectures for high energy density Lithium Sulfur batteries

Murugavel Shanthi, Pavithra (2020) Fundamental study of engineered cathode and Li-ion conducting electrolyte architectures for high energy density Lithium Sulfur batteries. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Rapid development in electric vehicle and portable electronic device technologies has made it imperative to identify new higher energy density (∼500 Wh/kg) battery systems than currently available Li-ion batteries (∼250 Wh/kg). Lithium-sulfur with a theoretical capacity of ∼1675 mAh/g has emerged as the leading next generation Li-ion battery system. However, sulfur cathodes are hamstrung by inherent poor electronic conductivity (∼1×10-15 S/m), volumetric expansion (∼80%) and more importantly, soluble polysulfide formation causing inferior cyclability, areal capacities and rate capabilities. This PhD dissertation overcomes these limitations by engineering electron conducting novel cathode architectures using metal organic frameworks (MOFs) and complex framework materials (CFMs) as primary sulfur hosts confining the volume expansion along with composite polymer electrolytes (CPEs) and directly deposited sulfur architectures (DDSA) combining polysulfide trapping agents (PTAs). The sulfur infiltrated MOF (S-MOF) and CFM hosts (S-CFMs) exhibit stable capacities of ~1000-1050 mAh/g with minimal fade rate (~0.12-0.19% loss/cycle) due to Lewis acid-base interactions of the MOF with polysulfides and concomitant sulfur bonding with the CFM carbon architecture yielding complete lithiated polysulfide species retention within the MOF and CFM structures. The CPEs and DDSA-PTA composite systems also exhibit excellent stability (~0.14% loss/cycle) upon extended cycling to (~200 cycles), highlighting the potential of these systems in preventing polysulfide dissolution in Li-S batteries. Fundamental aspects of the different strategies employed to resolve the core sulfur cathode problems of polysulfide dissolution and inferior electronic conductivity of sulfur are outlined. Results from the extensive materials, chemical and electrochemical characterization of these individual systems are also discussed.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Murugavel Shanthi, Pavithrapam127@pitt.eduPAM127
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairKumta, Prashantpkumta@pitt.eduPKUMTA
Committee MemberEnick, Robertrme@pitt.eduRME
Committee MemberMcKone, Jamesjmckone@pitt.eduJMCKONE
Committee MemberGrainger, Brandonbmg10@pitt.eduBMG10
Date: 3 August 2020
Date Type: Publication
Defense Date: 19 December 2019
Approval Date: 3 August 2020
Submission Date: 2 January 2020
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 306
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Chemical and Petroleum Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Li-S batteries
Date Deposited: 03 Aug 2021 05:00
Last Modified: 28 Feb 2023 15:22


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