Battery Cell Electrolyte Composition for Low Resistance Growth
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Solution Overview
Problem
Existing battery technologies using multiple positive electrode active materials suffer from rapid internal resistance increase and decreased capacity retention due to incompatible materials, leading to deteriorated power performance and cycle life.
Innovation Solution
A battery cell design incorporating a positive electrode active material with a one-dimensional ion transport channel and a metal salt with larger ionic radius in the electrolyte, along with specific weight ratios and discharge capacities, stabilizes the surface layer structure and reduces internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple different types of positive electrode active materials are used in combination to satisfy low cost and high specific capacity requirements, then the specific capacity and cost performance are improved, but the internal resistance increases rapidly during cycling and capacity retention rate declines rapidly
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the positive electrode active material has different compositions in different regions. The core contains a first positive electrode active material with specific properties, while the shell contains a second positive electrode active material with different properties optimized for stability and ion transport. This spatial differentiation of material properties allows the battery to achieve both high specific capacity from the core material and excellent capacity retention from the shell material, resolving the contradiction between quantity and reliability.
2Quantity of substance
If multiple different types of positive electrode active materials are used in combination to achieve high specific capacity, then the energy density is improved, but the power performance deteriorates significantly due to rapid internal resistance increase
Solution Approach 1:
The patent implements local quality by designing a core-shell structure where the shell material is specifically engineered with high ionic conductivity and a one-dimensional ion transport channel structure. This localized optimization of ion transport properties in the shell region enables rapid lithium ion diffusion, thereby maintaining high power performance while the core material provides high specific capacity, thus resolving the contradiction between energy density and power performance.
Solution Approach 2:
The patent applies dimensionality change by introducing a one-dimensional ion transport channel structure in the shell material. This one-dimensional channel provides a direct, low-resistance pathway for lithium ion transport, significantly enhancing ion diffusion kinetics compared to traditional three-dimensional diffusion paths. This structural innovation allows the battery to maintain high power performance while utilizing multiple positive electrode active materials for high specific capacity.
3Quantity of substance
If a positive electrode active material with high specific capacity is used, then the energy density is improved, but side reactions increase and cycle life decreases
Solution Approach 1:
The patent applies the intermediary principle by introducing a shell material as a protective layer between the core positive electrode active material and the electrolyte. This shell acts as a mediator that prevents direct contact and harmful side reactions between the high-capacity core material and the electrolyte, while still allowing lithium ion transport. The shell material with its one-dimensional ion transport channel structure facilitates ion transport while protecting the core material from degradation, thus resolving the contradiction between high specific capacity and reduced side reactions.
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 a low internal resistance increase rate, long cycle life, and improved power performance by stabilizing the electrode structure and optimizing electrolyte composition.
Implementation Method 1
the Me cations in the electrolytic solution will be intercalated into the surface layer of the first positive electrode active material during the discharge process of the battery
Implementation Method 2
the second positive electrode active material is provided with a one-dimensional ion transport channel, and an ionic conductivity of the first positive electrode active material is greater than that of the second positive electrode active material
Implementation Method 3
the lithium salt dissociates into lithium ions and first anions in the electrolytic solution, the metal Me salt dissociates into Me cations and second anions in the electrolytic solution
Data Source
AI summary
A battery cell comprises an electrolyte. The electrolyte solution contains an electrolyte salt, wherein the electrolyte salt contains lithium salt and metal Me salt, the ionic radius of Me positive ions is greater than the ionic radius of lithium ions, and the weight content of the lithium ions in the electrolyte is denoted as w1, and the weight content of the Me positive ions in the electrolyte is denoted as w2, both of which are based on the total weight of the electrolyte. In a charge and discharge test of a battery cell, the total discharge capacity of the battery cell is denoted as Q1, and the discharge capacity of the battery cell with a discharge voltage of 3.6 V is denoted as Q2. When the remaining capacity of the battery cell is greater than 90%, 0.8≤(Q2/Q1)/[w2/(w1+w2)]≤8.5 is satisfied.