Gel Polymer Electrolyte Layout for Lithium Metal Battery Stability
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Solution Overview
Problem
Lithium secondary batteries using lithium metal as a negative electrode face instability issues due to dendrite formation and passivation layer problems, leading to reduced cycle life and capacity, and existing solutions like protective layers and electrolyte composition changes are not economically viable or effective.
Innovation Solution
A lithium secondary battery design incorporating a gel polymer electrolyte with an ether-based solvent in the negative electrode and a liquid electrolyte with a carbonate-based solvent in the positive electrode, where the electrolyte liquid is impregnated into a polymer matrix in limited quantities to enhance stability and prevent mixing between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as a negative electrode active material to achieve high energy density and high capacity, then the theoretical energy density reaches 3,860 mAh/g, but lithium metal reacts with electrolyte liquid to form passivation layer and dendrites, causing internal short circuits and reducing battery stability and cycle life
Solution Approach 1:
The invention divides the electrolyte system into two separate compartments: a gel polymer electrolyte for the negative electrode and a liquid electrolyte for the positive electrode. This segmentation prevents direct contact between lithium metal and the liquid electrolyte, eliminating dendrite formation while maintaining high energy density through the gel polymer electrolyte's ability to accommodate lithium ions.
Solution Approach 2:
The gel polymer electrolyte acts as an intermediary between the lithium metal negative electrode and the liquid electrolyte positive electrode compartment. It provides a stable interface that prevents direct harmful reactions while allowing ionic conduction, thus maintaining both high energy density and battery stability.
2Reliability
If protective layers are introduced on lithium metal surface to prevent dendrite formation and improve stability, then battery stability improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention merges the protective layer function with the electrolyte system by using a gel polymer electrolyte that inherently provides protection against dendrite formation while serving as the functional electrolyte medium. This eliminates the need for separate protective coating layers, reducing structural complexity while maintaining stability.
Solution Approach 2:
The gel polymer electrolyte performs multiple functions simultaneously: it serves as the electrolyte medium for ionic conduction, provides mechanical protection against dendrite formation, and acts as a separator between electrodes. This multi-functionality eliminates the need for additional protective layers, simplifying the overall battery structure.
3Productivity
If electrolyte liquid content in gel polymer electrolyte is increased to improve ion conduction and charge-discharge efficiency, then charge-discharge efficiency improves, but electrolyte mixing between electrodes increases, reducing battery stability
Solution Approach 1:
The invention segments the electrolyte system into distinct gel polymer and liquid electrolyte compartments with different ionic conductivities. The gel polymer electrolyte on the negative electrode side has lower ionic conductivity, which limits electrolyte mixing while still providing sufficient charge-discharge efficiency for the high-capacity lithium metal electrode.
Solution Approach 2:
The invention changes the physical state parameter of the electrolyte from liquid to gel polymer form on the negative electrode side. This parameter change reduces the mobility and mixing tendency of the electrolyte while maintaining adequate ionic conductivity for efficient charge-discharge operation.
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 improves charge and discharge efficiency, extends cycle life, and maintains battery stability by minimizing electrolyte mixing and reaction, resulting in a high-performance lithium secondary battery with enhanced durability and capacity.
Implementation Method 1
the electrolyte liquid is impregnated into the polymer matrix in an amount of 30% by weight or less with respect to a total weight of the gel polymer electrolyte
Implementation Method 2
a separator provided between the positive electrode and the negative electrode
Implementation Method 3
a process of lithium ions of the positive electrode being intercalated and deintercalated to the negative electrode
Implementation Method 4
more lithium ions are capable of being intercalated and deintercalated through an alloying reaction with lithium
Data Source
AI summary
A lithium secondary battery, in which, by using different electrolytes in a positive electrode and a negative electrode, and using a gel polymer electrolyte, in which a small amount of an electrolyte liquid is impregnated into a polymer matrix, between the negative electrode and the separator, the stability and performance of the electrode may be improved, and therefore, the performance and lifetime of the lithium secondary battery may be enhanced.