Solid Electrolyte Bonding Layer for Delamination-Prone Li Metal Cells
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Solution Overview
Problem
Solid electrolytes used in rechargeable Li+ ion batteries face challenges such as delamination and insufficient electrical contact between electrodes, leading to increased interfacial impedance, which reduces battery power and capacity, especially when paired with a lithium metal negative electrode.
Innovation Solution
A bonding layer comprising a lithium salt, a polymer, and a solvent, such as a gel electrolyte, is introduced between the solid electrolyte separator and the positive electrode to enhance adhesion and reduce interfacial impedance, protecting the lithium metal negative electrode from exposure to the polymer or solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a solid electrolyte separator is used to separate electrodes, then battery weight and volume are reduced, but interfacial impedance increases due to delamination and insufficient electrical contact
Solution Approach 1:
The patent introduces a bonding agent layer as an intermediary substance between the solid electrolyte separator and the electrodes. This bonding agent serves as a mediator that improves interfacial adhesion and electrical contact while maintaining the benefits of solid electrolyte usage. The bonding agent fills gaps and ensures consistent contact between the rigid solid electrolyte and the electrodes, resolving the delamination issue without requiring changes to the solid electrolyte material itself.
Solution Approach 2:
The patent creates a composite structure by combining the solid electrolyte separator with a bonding agent layer that has different properties. The bonding agent layer acts as an intermediate material that bridges the solid electrolyte and the electrodes, providing both mechanical adhesion and electrical conductivity. This composite approach allows the system to maintain the weight reduction benefits of solid electrolytes while overcoming their poor interfacial contact issues.
2Device complexity
If solid electrolyte separator is directly laminated to electrodes, then device structure is simplified, but interfacial impedance rises due to non-perfect alignment and gaps
Solution Approach 1:
The bonding agent layer serves as an intermediary that compensates for alignment imperfections between the solid electrolyte separator and the electrodes. It fills gaps and creates a continuous conductive path, ensuring reliable electrical contact even when perfect alignment is not achieved during assembly.
Solution Approach 2:
The bonding agent layer can be designed with porous or flexible structure that allows it to conform to the electrode surface topology. This porous structure enables the bonding agent to fill voids and irregularities at the interface, ensuring consistent electrical contact across the entire electrode surface while maintaining a relatively simple overall device structure.
3Quantity of substance
If solid electrolyte separator is used with lithium metal negative electrode, then energy density is increased, but delamination occurs during charge-discharge expansion and contraction
Solution Approach 1:
The bonding agent layer acts as a mediator between the solid electrolyte separator and the lithium metal negative electrode. During charge-discharge cycles, the lithium metal electrode expands and contracts, but the bonding agent layer accommodates these dimensional changes while maintaining adhesion to both the electrode and the solid electrolyte, preventing delamination.
Solution Approach 2:
The bonding agent layer is designed with specific mechanical properties that allow it to accommodate the expansion and contraction of the lithium metal electrode during cycling. By carefully selecting the bonding agent's elasticity, adhesion strength, and thickness parameters, the system maintains stable interfacial contact despite the dynamic dimensional changes of the lithium metal electrode.
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
The bonding layer significantly lowers interfacial impedance by a factor of at least 10, 100, or 1000, improving the electrochemical performance and stability of the battery by maintaining direct contact and preventing chemical reactions that degrade performance.
Implementation Method 1
the bonding layer significantly lowers interfacial impedance by a factor of at least 10, 100, or 1000, improving the electrochemical performance
Implementation Method 2
volatilizing at least one of the two or more solvents to form a porous gel electrolyte on a solid separator
Data Source
AI summary
Set forth herein are electrochemical cells which include a negative electrode current collector, a lithium metal negative electrode, an oxide electrolyte membrane, a bonding agent layer, a positive electrode, and a positive electrode current collector. The bonding agent layer advantageously lowers the interfacial impedance of the oxide electrolyte at least at the positive electrode interface and also optionally acts as an adhesive between the solid electrolyte separator and the positive electrode interface. Also set forth herein are methods of making these bonding agent layers including, but not limited to, methods of preparing and depositing precursor solutions which form these bonding agent layers. Set forth herein, additionally, are methods of using these electrochemical cells.