Thin Flexible Solid Electrolyte for Lithium-Ion Battery
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Solution Overview
Problem
Lithium-ion batteries face capacity fading due to unwanted consumption of lithium ions, primarily caused by transition metal ions from the positive electrode migrating through the liquid electrolyte and damaging the negative electrode and solid-electrolyte interface.
Innovation Solution
A thin, flexible ceramic membrane with closely spaced pores is used, filled with a solid electrolyte to block transition metal ions while allowing lithium ions to flow between the electrodes, thereby preventing damage to the negative electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid electrolyte is used to transport lithium ions between electrodes, then lithium ion transport is enabled, but transition metal ions from the positive electrode migrate through the liquid electrolyte and damage the negative electrode
Solution Approach 1:
A solid electrolyte layer is introduced as an intermediary between the liquid electrolyte and the negative electrode. This solid electrolyte selectively blocks transition metal ions from migrating to the negative electrode while still permitting lithium ion transport, thus resolving the contradiction between enabling lithium ion transport and preventing harmful ion migration.
Solution Approach 2:
The solid electrolyte is implemented as a porous membrane structure that allows lithium ions to pass through while physically blocking larger transition metal ions. The porous structure enables selective ion transport based on size exclusion, maintaining reliability by preventing harmful ion migration while preserving lithium ion conductivity.
2Object-affected harmful factors
If a solid electrolyte membrane is introduced to block transition metal ions, then harmful ion migration is prevented, but device structure becomes more complex
Solution Approach 1:
The solid electrolyte membrane is integrated directly with the existing liquid electrolyte system, combining the benefits of liquid electrolyte flexibility with solid electrolyte protective function. This merging approach prevents negative electrode damage while minimizing additional structural complexity by seamlessly integrating the protective layer into the existing electrolyte architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces capacity fading, maintaining up to 90% of the discharge capacity for extended cycling, as demonstrated in a lithium-ion cell with a graphite negative electrode and lithium-nickel-manganese oxide positive electrode.
Implementation Method 1
a solid electrolyte, carried on a thin, flexible membrane, and covering pores extending through the membrane, is used to permit transport of lithium ions between the electrodes while blocking negative electrode-damaging ions
Implementation Method 2
permit transport of lithium ions between the electrodes while blocking negative electrode-damaging ions
Data Source
AI summary
A lithium-ion conducting, solid electrolyte is deposited on a thin, flexible, porous alumina membrane which is placed between co-extensive facing side surfaces of a porous, lithium-accepting, negative electrode and a positive electrode formed of a porous layer of particles of a compound of lithium, a transition metal element, and optionally, another metal element. A liquid electrolyte formed, for example, of LiPF6 dissolved in an organic solvent, infiltrates the electrode materials of the two porous electrodes for transport of lithium ions during cell operation. But the solid electrolyte permits the passage of only lithium ions, and the negative electrode is protected from damage by transition metal ions or other chemical species produced in the positive electrode of the lithium-ion cell.