Design of Sulfide-based Hybrid Electrolytes for Stable All-Solid-State Batteries
- Title
- Design of Sulfide-based Hybrid Electrolytes for Stable All-Solid-State Batteries
- Authors
- 김가현
- Date Issued
- 2023
- Publisher
- 포항공과대학교
- Abstract
- The growing demand for high energy density and safety in energy storage systems
(ESSs) and electric vehicles (EVs) has led to the exploration of next-generation
batteries using Li metal anodes and solid electrolytes (SEs) for all-solid-state batteries
(ASSBs). High capacity (3,860 mAh/g) and the lowest reduction potential (-3.040 V
vs. Li/Li+) characterize lithium metal as a promising candidate, since SEs offer
theoretical prevention of lithium dendrite growth. Especially, sulfide solid electrolytes
(SSEs) exhibit high ionic conductivity (1~25 mS/cm) and soft mechanical properties
at room temperature, which are advantageous for battery performance. Among SSEs,
Li6PS5Cl (LPSCl) has shown promising results but suffers from unstable electrodeelectrolyte
interface issues, limiting their practical application. This study investigates
hybrid liquid electrolyte/sulfide solid electrolyte (LE/SSE) systems to enhance
interfacial stability focusing on commonly employed LEs in lithium-ion batteries
(LIBs). Carbonate-based (1M LiPF6, EC/DEC = 3/7) and ether-based (1M LiTFSI,
DOL/DME = 5/5) LEs were applied with small amounts to Li6PS5Cl (LPSCl) solid
electrolyte. Additionally, carbonate-based (1M LiTFSI, EC/DEC = 3/7) LE was
combined with LPSCl to examine the effect of Li salts. First of all, ether-based LE
caused serious side reaction with LPSCl with a high donor number. Accordingly, the
ether-based hybrid electrolyte showed low ionic conductivity and poor symetric cell
performance. The hybrid system using carbonate-based LE demonstrated improved
interfacial contact on the anode side, leading to the formation of an in-situ fluorinerich
solid electrolyte interphase (SEI) layer and extended cell lifespan (over 450 hours
for symmetric cell and over 100 cycles with high CE of ~95 % for half cell) even under conditions without assembly pressure or additional processes. The reactivity of carbonate-based LE and LPSCl is negligible in actual cell performance, and by introducing a small amount of liquid electrolyte to the interface, lithium ion movement is promoted and crack formation is much suppressed than bare solid electrolyte and
ether-based hybrid electrolyte. However, challenges persisted at high voltage ranges
due to serious side reactions. Potential solutions to overcome these limitations include
implementing a 3D structure on the anode to restrict the physical contact between the
cathode and the LE, using cathodes that operate within a low voltage range to limit
the overall voltage band to 2.5 V, and identifying an optimal electrolyte composition
that minimizes side reactions between LE and LPSCl under high voltage ranges. This
study highlights the benefits and drawbacks of hybrid LE/SSE systems, providing
valuable insights and potential solutions for future development.
- URI
- http://postech.dcollection.net/common/orgView/200000692094
https://oasis.postech.ac.kr/handle/2014.oak/118404
- Article Type
- Thesis
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