Prismatic Battery Anode Layering and Electrolyte for Swelling Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rectangular-shaped non-aqueous electrolyte secondary batteries with Si-based active materials face significant swelling issues during charging and discharging cycles, which can lead to stress and damage in battery modules.
Innovation Solution
The battery design incorporates a negative electrode with a multilayer structure, where the first layer includes a Si-based active material, polyacrylic acid, and a first carbon-based active material, and the second layer consists of a second carbon-based active material. The non-aqueous electrolyte contains a cyclic carbonate with a specific volume range and vinylene carbonate to control swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a Si-based active material is used in the negative electrode to increase lithium ion intercalation capacity, then the battery capacity is improved, but the negative electrode swells due to large volume changes during charging/discharging cycles
Solution Approach 1:
The negative electrode mixture layer is divided into two distinct layers: a first layer containing the Si-based active material with polyacrylic acid binder, and a second layer containing carbon-based active material. This segmentation isolates the swelling Si-based material from direct contact with the electrolyte while maintaining high capacity, as the carbon layer acts as a protective barrier that accommodates volume changes.
Solution Approach 2:
The patent uses a composite structure combining Si-based active material with carbon-based active material in a layered configuration. The Si-based layer provides high lithium ion intercalation capacity while the carbon-based layer provides structural stability and prevents electrolyte penetration, creating a composite material system that achieves both high capacity and swelling resistance.
2Quantity of substance
If the negative electrode swells during charging/discharging cycles, then the battery capacity is maintained, but the battery itself swells and applies stress to the battery module
Solution Approach 1:
By segmenting the negative electrode into two layers, the harmful swelling effect is contained within the first layer while the second layer acts as a protective barrier. This prevents the swelling from transmitting to the battery casing and module, eliminating the harmful effects while preserving the capacity benefits of Si-based material.
Solution Approach 2:
The carbon-based second layer serves as an intermediary between the Si-based first layer and the electrolyte/battery casing. It mediates the interaction by allowing lithium ion transport while blocking the transmission of swelling forces, thus protecting the battery structure from stress and damage.
3Object-affected harmful factors
If a carbon-containing layer is formed on the negative electrode mixture layer to prevent swelling, then battery swell is reduced, but the lithium ion intercalation capacity decreases
Solution Approach 1:
Instead of forming a thin carbon-containing layer that limits capacity, the patent segments the electrode into two substantial layers with defined mass ratios. The carbon-based second layer is thick enough to provide effective protection against swelling while being configured (10-40 mass%) to maintain high overall lithium ion intercalation capacity.
Solution Approach 2:
The patent optimizes the mass ratio parameters of the two layers, specifying that the first layer constitutes 60-90 mass% and the second layer 10-40 mass%. This parameter optimization ensures that the protective carbon layer is sufficiently thick to prevent swelling while maintaining high capacity, resolving the trade-off between protection and performance.
4Reliability
If the content of ethylene carbonate is increased to improve electrolyte performance, then the electrolyte effectiveness is improved, but the battery swelling increases
Solution Approach 1:
The patent precisely controls the ethylene carbonate content parameter, limiting it to 10 volume% or less of the total non-aqueous solvent. This parameter optimization balances electrolyte performance (maintaining sufficient ionic conductivity and stability) with swelling control (minimizing volume expansion during cycling).
Solution Approach 2:
The patent creates different local compositions: the first layer has specific binding properties with polyacrylic acid, the second layer has carbon-based composition, and the electrolyte has controlled EC content. This local quality differentiation allows each region to perform its specific function optimally while contributing to overall swelling resistance.
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 design effectively suppresses battery swelling during charging and discharging cycles, reducing stress on battery modules and enhancing the battery's input and cyclic characteristics.
Implementation Method 1
a non-aqueous electrolyte having an electrolyte salt and a non-aqueous solvent
Implementation Method 2
a Si-based active material can intercalate a larger amount of lithium ions per unit volume than a carbon-based active material such as graphite
Implementation Method 3
the first layer including a first carbon-based active material, a Si-based active material, and polyacrylic acid or a salt thereof
Implementation Method 4
the non-aqueous solvent includes a cyclic carbonate, the content of the cyclic carbonate is 20% by volume or more and 30% by volume or less based on the total volume of the non-aqueous solvent
Implementation Method 5
the non-aqueous electrolyte includes vinylene carbonate
Data Source
Figure 1~2
AI summary
This prismatic non-aqueous electrolyte secondary battery is provided with a negative electrode and a nonaqueous electrolyte. The negative electrode is provided with a negative electrode current collector and a negative electrode mixture layer formed on the negative electrode current collector. The negative electrode mixture layer comprises a first layer containing a first carbon active material, a Si active material and a polyacrylic acid or a salt thereof, and a second layer containing a second carbon active material. The nonaqueous solvent configuring the nonaqueous electrolyte contains a cyclic carbonate. The total content of the cyclic carbonate is 20-30 vol% of the total volume of the nonaqueous solvent, and the content of the ethylene carbonate belonging to the cyclic carbonate is less than or equal to 10 vol% of the total volume of the nonaqueous solvent. The nonaqueous electrolyte contains vinylene carbonate. With this configuration, it is possible to provide a prismatic nonaqueous electrolyte secondary battery in which swelling of the battery accompanying charge/discharge cycles is suppressed.