Secondary Battery Swelling Suppression via Composite Electrode
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Solution Overview
Problem
Conventional lithium ion secondary batteries face issues with capacity deterioration and swelling due to volume changes during charging and discharging, particularly when using silicon oxide as a negative electrode active substance, and there is a lack of understanding regarding the interactions between the negative electrode, binder, electrolyte liquid, electrode assembly, and package components.
Innovation Solution
A lithium ion secondary battery design featuring a negative electrode composed of metal, metal oxide, and carbon materials bound with polyimides or polyamide-imides, and an electrolyte liquid containing specific imide compounds to suppress swelling and enhance cycle performance, with a stacked laminate type electrode assembly to minimize volume changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon oxide is used as a negative electrode active substance to achieve high energy density, then the battery capacity is improved, but capacity deterioration becomes significantly large when charging and discharging at 45°C or higher
Solution Approach 1:
A coating layer comprising at least one of a silicon compound and an oxide is formed on the surface of the silicon fine crystal. This coating layer acts as an intermediary protective barrier between the silicon fine crystal and the electrolyte, preventing direct harmful interactions while allowing lithium ion insertion/extraction, thereby maintaining high capacity while improving cycle stability at elevated temperatures
Solution Approach 2:
The negative electrode active substance is constructed as a composite material system where silicon fine crystals are dispersed within a silicon compound matrix, and the surface is further coated with silicon compound and/or oxide layers. This composite structure combines the high capacity of silicon with the stability and protective properties of silicon compounds and oxides, resolving the contradiction between capacity and reliability
2Quantity of substance
If silicon oxide is used as a negative electrode active substance to achieve high energy density, then the battery capacity is improved, but swelling occurs due to volume changes during charging and discharging
Solution Approach 1:
The coating layer of silicon compound and/or oxide serves as a mediator that accommodates volume changes of the silicon fine crystal during lithium insertion/extraction. This layer absorbs expansion stress and prevents direct transmission to the electrode structure and battery package, thereby suppressing swelling while maintaining high capacity
Solution Approach 2:
The coating layer acts as a flexible protective shell around the silicon fine crystal particles. This thin film structure allows for volume expansion during charging while maintaining structural integrity, preventing electrode disintegration and battery swelling, thus enabling high capacity without volume increase
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 solution effectively suppresses swelling and improves cycle performance by using a combination of metal, metal oxide, and carbon materials with polyimides or polyamide-imides, and specific imide compounds in the electrolyte liquid, maintaining battery performance even at elevated temperatures.
Implementation Method 1
metal particles that can be alloyed with lithium
Implementation Method 2
an oxide particle that can absorb and desorb lithium ion
Implementation Method 3
a carbon material particle that can absorb and desorb lithium ion
Data Source
AI summary
The object of an exemplary embodiment of the invention is to provide a secondary battery with a high performance in which the generation of the swelling can be suppressed and in which the cycle property is excellent. An exemplary embodiment of the invention is a secondary battery, comprising an electrode assembly in which a positive electrode and a negative electrode are oppositely disposed, an electrolyte liquid, and a package which encloses the electrode assembly and the electrolyte liquid inside; wherein the negative electrode is formed by binding a negative electrode active substance, which comprises metal (a) that can be alloyed with lithium, metal oxide (b) that can absorb and desorb lithium ion, and carbon material (c) that can absorb and desorb lithium ion, to a negative electrode collector with at least one selected from polyimides and a polyamide-imides; and wherein the electrolyte liquid comprises a compound represented by any one of predetermined formulae.