Porous Sulfur Cathode Processing for Safer High-Capacity Li-Ion Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion secondary batteries face challenges in achieving high capacity, long cycle life, and safety due to the dissolution of lithium polysulfide during discharge, which reduces charge and discharge efficiency and leads to potential short circuits and heat generation.
Innovation Solution
A production method involving surface modification of spherical resin particles through heat treatment to form a porous structure, followed by mixing with sulfur and subsequent heat treatment to form a sulfur compound, which is then used as a positive electrode active material in a lithium-sulfur battery, enhancing the battery's capacity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as negative electrode active material with sulfur-based positive electrode, then battery capacity and energy density are improved, but battery safety and reliability deteriorate due to lithium polysulfide dissolution causing short circuits and heat generation
Solution Approach 1:
A lithium ion conductive layer is introduced as an intermediary between the negative electrode (lithium metal) and positive electrode (sulfur-based). This layer selectively allows lithium ion transport while preventing direct contact and reaction between electrodes, thereby maintaining high capacity while improving safety and preventing short circuits
Solution Approach 2:
The lithium ion conductive layer is designed with a porous structure that enables efficient lithium ion diffusion while providing physical separation. The porous morphology maintains ion conductivity pathways while the overall structure prevents harmful direct contact between electrodes, addressing both capacity and safety requirements
2Reliability
If lithium ion conductive layer with porous structure is formed between electrodes, then battery safety and ion conductivity are improved, but device complexity increases
Solution Approach 1:
The lithium ion conductive layer performs multiple functions simultaneously: it acts as a safety barrier preventing short circuits, serves as an ion transport pathway for high conductivity, and provides structural separation between electrodes. This multi-functionality reduces the need for additional separate components, thereby limiting complexity 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 method results in a lithium-ion secondary battery with improved capacity, cycle performance, and safety, reducing the risk of short circuits and heat generation, while maintaining high charge and discharge efficiency and extending the battery's lifespan.
Implementation Method 1
a spherical resin is subjected to first heat treatment at a temperature higher than or equal to 500° C. in an inert atmosphere. The contraction of a particle, the void formation due to a gas release from an inside of the particle, the crack on a particle surface, and the like are caused in the spherical resin by the heating
Implementation Method 2
The contraction of a particle, the void formation due to a gas release from an inside of the particle, the crack on a particle surface, and the like are caused in the spherical resin by the heating so as to form a support for sulfur
Implementation Method 3
At the time of discharging, the lithium metal in the negative electrode is dissolved in an electrolyte solution to be an ion
Implementation Method 4
the ion reacts with sulfur in the positive electrode to be oxidized, so that a reaction intermediate product, lithium polysulfide (Li2Sn (2≤n≤8)), is formed and then followed by lithium sulfide (Li2S)
Data Source
AI summary
One embodiment of the present invention is to provide a high-capacity lithium ion secondary battery and a production method thereof. To perform surface modification, a spherical resin is subjected to first heat treatment at a temperature higher than or equal to 500° C. in an inert atmosphere. By the heating, the contraction of a particle, the void formation due to a gas release from an inside of the particle, the crack on a particle surface, and the like are caused so as to form a support for sulfur that is to be mixed later. Obtained spherical particles and sulfur powder are mixed and then stored in a container. The mixture in the container is subjected to second heat treatment at a temperature higher than or equal to 120° C. without being exposed to outside air.