Positive Electrode Film Layer Tuning for High-Areal-Density Batteries
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Solution Overview
Problem
Existing secondary batteries face challenges in achieving both high energy density and dynamic performance, with thick coatings leading to increased polarization resistance and decreased dynamic performance.
Innovation Solution
A secondary battery design incorporating an electrolyte solution with an organic lithium salt and a positive electrode film layer optimized by controlling the areal density and composition of the positive electrode active material, including particles of varying sizes and types, to enhance ionic conductivity and reduce impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the areal density of the positive electrode film layer is increased to improve energy density, then the energy density per unit area is improved, but the ion transmission in the positive electrode film layer is hindered, causing decreased dynamic performance and rate performance
Solution Approach 1:
The patent applies parameter changes by optimizing the areal density of the positive electrode film layer to a specific range (15-30 mg/cm²) and controlling the thickness (5-20 μm) to achieve a balance between energy density and ion transmission. This parameter optimization resolves the contradiction by finding the optimal values that simultaneously improve energy density while maintaining acceptable dynamic performance.
Solution Approach 2:
The patent uses composite materials by combining the positive electrode film layer with specific electrolyte compositions containing lithium salts (such as LiPF6, LiBF4, LiCF3SO3) and cyclic carbonates (EC, DEC, DMC). This composite system enhances both the energy density and ion transmission properties, resolving the contradiction between high areal density and good dynamic performance.
2Quantity of substance
If the coating thickness is increased to improve energy density, then the energy storage capacity is improved, but the polarization resistance increases, causing decreased dynamic performance
Solution Approach 1:
The patent applies parameter changes by controlling the positive electrode film layer thickness within the range of 5-20 μm and areal density within 15-30 mg/cm². These optimized parameters reduce the polarization resistance while maintaining high energy storage capacity, effectively resolving the contradiction between energy density and dynamic performance.
Solution Approach 2:
The patent employs porous materials by using a porous positive electrode film layer structure that allows efficient lithium ion transport. The porous structure reduces the effective transmission path for ions while maintaining high areal density, thereby reducing polarization resistance and improving dynamic performance without sacrificing energy storage capacity.
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 design improves both energy density and dynamic performance by optimizing the positive electrode film layer and electrolyte interface, ensuring high ionic conductivity and stable lithium ion transmission.
Implementation Method 1
The organic lithium salt in the electrolyte solution can effectively improve the ionic conductivity of the electrolyte solution, reduce the impedance of the electrolyte solution/electrode interface
Implementation Method 2
The organic lithium salt in the electrolyte solution can improve the transmission rate of lithium ions in the positive electrode film layer
Implementation Method 3
form a stable passivation film with good ionic conductivity on the electrode surface, and improve the interface stability
Data Source
AI summary
A secondary battery includes an electrolyte solution and a positive electrode. The electrolyte solution contains an organic lithium salt. The positive electrode includes a positive electrode film layer. The energy density per unit area of the positive electrode film layer on a single side is 18-37 mWh/cm2, and optionally 18-35.7 mWh/cm2.