Lithium Secondary Battery Gel Electrolyte for Thin Anode Design
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Solution Overview
Problem
Conventional lithium secondary batteries have insufficient energy density, and there is a need for a lithium secondary battery with improved energy density and manufacturing methods.
Innovation Solution
A lithium secondary battery is manufactured with a negative electrode that does not include a negative-electrode active material, utilizing a gel electrolyte applied to a separator surface and forming a thin negative electrode on the gel electrolyte, with specific polymer and solvent compositions to enhance adhesion and conductivity, and optionally forming a positive electrode current collector on the other surface of the separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a negative electrode with high content of negative-electrode active material is used, then the battery capacity is improved, but the energy density is reduced due to increased volume and mass
Solution Approach 1:
The patent changes the fundamental parameter of negative electrode composition by reducing the content of negative-electrode active material to 10 mass% or less, transforming it from a material-rich electrode to a thin functional layer that serves as a substrate for lithium metal precipitation, thereby achieving high capacity with minimal volume
Solution Approach 2:
The patent extracts the primary function of energy storage from the negative electrode active material and relocates it to lithium metal precipitation, allowing the negative electrode to serve only as a thin structural substrate rather than a bulk energy storage component
2Volume of moving object
If the negative electrode is made thinner to reduce volume, then the energy density is improved, but the adhesion to the separator deteriorates
Solution Approach 1:
The patent introduces gel electrolyte as an intermediary substance between the thin negative electrode and the separator, providing adhesive functionality that compensates for the reduced contact area of the thin electrode while maintaining structural integrity
Solution Approach 2:
The patent creates a composite structure where gel electrolyte (containing polymer and electrolyte solution) is applied to the separator surface, forming a multi-functional layer that combines adhesion, ion conduction, and mechanical support properties
3Strength
If a gel electrolyte with high polymer content is used to improve adhesion, then the adhesion is improved, but the ionic conductivity is reduced
Solution Approach 1:
The patent optimizes the composition parameters of gel electrolyte by controlling the polymer content at 5-90 parts by mass and electrolyte solution content at 10-95 parts by mass based on 100 parts by mass of gel electrolyte, achieving a balance between adhesion and ionic conductivity
Solution Approach 2:
The patent creates a composite gel electrolyte system combining polymer matrix (for adhesion and structure) with electrolyte solution (for ionic conductivity), where the two components work synergistically to provide both mechanical strength and electrical function
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 resulting lithium secondary battery achieves higher energy density due to reduced volume and mass, improved adhesion, and stabilized cycle characteristics, with potential thicknesses of 0.5 µm to 6 µm for the negative electrode and 1.0 µm to 6.0 µm for the positive electrode current collector.
Implementation Method 1
a gel electrolyte is applied to one of the surfaces of the separator
Implementation Method 2
lithium secondary batteries which are charged/discharged by the transfer of lithium ions between their positive electrode and negative electrode
Data Source
Figure 1~2
Figure 3~4
AI summary
The purpose of the present invention is to provide a method of manufacturing a lithium secondary battery having a high energy density. The method of manufacturing a lithium secondary battery having a positive electrode, a negative electrode not having a negative-electrode active material, and a separator includes a step of applying a gel electrolyte to one of the surfaces of the separator and a step of forming the negative electrode on the surface of the gel electrolyte, wherein the negative electrode is thinner than the gel electrolyte.