Silicon-Carbon Anode Electrolyte for High-Temperature Cycle Stability
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Solution Overview
Problem
Secondary batteries with high-capacity electrode materials face issues of poor cycle performance and thermal stability, particularly at high temperatures, necessitating improvements in the cooperation of battery components.
Innovation Solution
A secondary battery design incorporating a silicon-carbon composite material with a three-dimensional network cross-linked pore structure and a lithium sulfonimide salt electrolyte, where the lithium sulfonimide salt forms a solid electrolyte film with sulfur and nitrogen oxides on the silicon-based material interface, enhancing thermal and chemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high capacity electrode materials are adopted to increase battery energy, then the battery capacity is improved, but the cycle performance and thermal stability deteriorate
Solution Approach 1:
A lithium sulfonimide salt is introduced as an intermediary substance in the electrolyte that reacts with the high-capacity electrode material to form a protective interface film. This film acts as a mediator that allows lithium ion transport while preventing harmful reactions between the electrode and electrolyte, thus maintaining both high capacity and good cycle performance
Solution Approach 2:
The battery employs a composite electrolyte system combining lithium sulfonimide salt with traditional electrolyte components. This composite approach creates a synergistic effect where the lithium sulfonimide salt provides protective film formation while the base electrolyte maintains ionic conductivity, resolving the contradiction between capacity and reliability
2Quantity of substance
If high capacity electrode materials are used to increase energy density, then the battery energy is improved, but the thermal stability deteriorates
Solution Approach 1:
The lithium sulfonimide salt serves as a thermal protective intermediary that forms a stable interface film on the electrode surface. This film acts as a thermal barrier that prevents exothermic reactions between the high-capacity electrode material and the electrolyte, maintaining thermal stability while preserving high energy density
Solution Approach 2:
The potential harmful thermal reactions between high-capacity electrode materials and electrolyte are converted into beneficial effects through controlled reaction products. The lithium sulfonimide salt directs the reaction to form protective films containing sulfur oxide and nitrogen oxide, which provide thermal stability while maintaining the high capacity benefits
3Quantity of substance
If silicon content is increased to improve capacity, then the energy density is improved, but the volume change and structural stability deteriorate
Solution Approach 1:
A porous carbon matrix structure is employed to host the silicon particles. The porous structure provides void space that accommodates silicon volume expansion during lithiation, preventing structural collapse while maintaining electrical conductivity and lithium ion transport pathways
Solution Approach 2:
A silicon-carbon composite structure is created where silicon particles are embedded in a carbon matrix. The carbon component provides structural stability and conductivity while the silicon provides high capacity, achieving both high silicon content and structural stability
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 improves high-temperature cycle performance and storage performance by stabilizing the electrode-electrolyte interface, maintaining mechanical strength, and optimizing silicon loading, thereby enhancing energy density and cycle life.
Implementation Method 1
the lithium sulfonimide salt can easily enter the pore structure of the silicon-carbon composite material to generate a solid electrolyte film containing sulfur oxide and nitrogen oxide on the interface of a silicon-based material
Data Source
AI summary
A secondary battery and an electrical apparatus comprising the secondary battery. The secondary battery comprises: a negative pole piece and an electrolyte. The negative pole piece of the secondary battery comprises a silicon-carbon composite material having a three-dimensional-network cross-linked pore structure, and the electrolyte of the secondary battery comprises lithium fluorosulfonyl imide.