LFP Battery Electrolyte Composition for High-Loading Cathode Wetting
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Solution Overview
Problem
Lithium iron phosphate-based positive electrode active materials in lithium secondary batteries face challenges with insufficient electrolyte impregnation, leading to increased resistance and degraded lifespan due to high loading amounts required for high energy density.
Innovation Solution
A lithium secondary battery design incorporating lithium iron phosphate particles with a specific loading amount, using a non-aqueous electrolyte composed of ethylene carbonate, dimethyl carbonate, and vinylene carbonate in specific ratios to improve electrolyte impregnation and negative electrode stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the lithium iron phosphate-based active material is used in a high loading amount to increase energy density, then the energy density of the positive electrode and lithium secondary battery is improved, but the non-aqueous electrolyte cannot be sufficiently impregnated into the positive electrode, resulting in difficulty expressing capacity, increased resistance, and degraded lifespan
Solution Approach 1:
The patent changes the chemical composition parameters of the non-aqueous electrolyte by specifying particular additives and their concentration ranges. This allows the electrolyte to be sufficiently impregnated into the high-loading positive electrode while maintaining capacity expression and lifespan performance
Solution Approach 2:
The patent introduces specific electrolyte additives as intermediary substances that facilitate the impregnation process. These additives act as mediators between the electrolyte and the high-loading positive electrode, enabling sufficient penetration without compromising battery performance
2Use of energy by moving object
If the lithium iron phosphate-based active material is used in a high loading amount to increase energy density, then the energy density of the positive electrode and lithium secondary battery is improved, but the capacity expression becomes difficult
Solution Approach 1:
The patent modifies the electrolyte composition parameters to enable sufficient impregnation into the high-loading positive electrode, which in turn enables proper capacity expression. The specific additive concentrations are tuned to achieve both high energy density and full capacity utilization
3Use of energy by moving object
If the lithium iron phosphate-based active material is used in a high loading amount to increase energy density, then the energy density of the positive electrode and lithium secondary battery is improved, but the resistance is increased
Solution Approach 1:
The patent adjusts the electrolyte composition parameters, specifically the types and concentrations of additives, to reduce resistance in high-loading positive electrodes. This allows maintaining high energy density while minimizing the harmful resistance effect
4Use of energy by moving object
If the lithium iron phosphate-based active material is used in a high loading amount to increase energy density, then the energy density of the positive electrode and lithium secondary battery is improved, but the lifespan is degraded
Solution Approach 1:
The patent optimizes the electrolyte composition parameters, particularly the additive types and their concentration ratios, to protect the positive electrode structure during cycling. This enables the battery to maintain high energy density while achieving excellent lifespan performance of 90% capacity retention after 200 cycles
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 achieves excellent capacity expression, lifespan performance, and reduced resistance by optimizing electrolyte impregnation and negative electrode stability, maintaining capacity retention rates and resistance increase within specified limits.
Implementation Method 1
a high-loading lithium iron phosphate positive electrode has a problem in that it is difficult for a non-aqueous electrolyte to be sufficiently impregnated into the positive electrode
Implementation Method 2
the ratio of the weight of the vinylene carbonate to the weight of the dimethyl carbonate is greater than 0 to 0.2 or less, to enhance electrolyte impregnation and negative electrode reduction stability
Data Source
AI summary
Provided is a lithium secondary battery including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte, wherein the positive electrode includes a positive electrode active material comprising lithium iron phosphate particles, and the positive electrode has a loading amount of 450 mg/25 cm2 to 740 mg/25 cm2, and the non-aqueous electrolyte includes a lithium salt, an organic solvent, and an additive, wherein the organic solvent includes ethylene carbonate, and dimethyl carbonate, and the dimethyl carbonate is included in 5 vol % to 75 vol % in the organic solvent, and the additive contains vinylene carbonate, and the weight ratio of the vinylene carbonate to the dimethyl carbonate is greater than 0 to 0.2 or less.