Silicon-Carbon Anode and Carboxylate Electrolyte for Cycle Stability
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Solution Overview
Problem
Existing secondary batteries face challenges in achieving high energy density while maintaining excellent cycle performance and dynamic performance due to the poor cycle performance and volume change of silicon-based negative electrode materials.
Innovation Solution
A secondary battery design incorporating a silicon-carbon composite material with a three-dimensional network cross-linked pore structure and a carboxylate compound electrolyte, which enhances ion transmission and reduces internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode material is used to increase energy density, then specific capacity is improved, but cycle performance deteriorates due to volume change
Solution Approach 1:
The patent employs a porous carbon coating layer with controlled pore structure on the silicon-based negative electrode material. The porous structure accommodates volume expansion of silicon during charging while maintaining structural integrity, thereby improving cycle performance without sacrificing specific capacity
Solution Approach 2:
The patent creates a composite structure combining silicon-based active material with carbon matrix and porous coating layers. This composite design leverages the high capacity of silicon while the carbon matrix provides structural stability and conductive pathways, resolving the contradiction between capacity and cycle life
2Quantity of substance
If silicon content is increased to improve energy density, then specific capacity is improved, but internal resistance increases due to poor ion transmission
Solution Approach 1:
The porous carbon coating layer provides interconnected pore channels that facilitate efficient ion transport throughout the electrode structure. This porous architecture reduces internal resistance by creating multiple ion conduction pathways while maintaining high silicon content for energy density
Solution Approach 2:
The patent applies different functional layers with specific local properties: a porous carbon coating layer for ion transport, conductive additives in specific regions, and controlled surface chemistry. This local optimization ensures good ion transmission throughout the electrode while maintaining high overall silicon content
3Productivity
If porosity is increased to improve ion transmission, then charge discharge performance is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent uses a porous carbon coating layer where the porous structure provides ion transmission channels while the carbon matrix maintains mechanical strength. The controlled porosity and interconnected pore structure allow fast ion transport without compromising the structural integrity of the electrode
Solution Approach 2:
The composite structure combines porous carbon material with binder and conductive additives to create a mechanically robust electrode that maintains structural integrity while providing efficient ion transport pathways through the porous network
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 combination improves cycle capacity retention rate, charge and discharge capabilities, and energy density by stabilizing the silicon volume change and promoting ion migration.
Implementation Method 1
the carboxylate compound matched in the electrolyte has low viscosity and can easily enter the three-dimensional network cross-linked pore structure of the silicon-carbon composite material, such that the transmission of ions at an active material/electrolyte interface is promoted, the interface impedance is effectively reduced
Implementation Method 2
The silicon-carbon composite material having a three-dimensional network cross-linked pore structure has a stable porous skeleton and good mechanical strength, and can effectively reduce the volume change of silicon before and after charging and discharging
Data Source
AI summary
A secondary battery and an electric device comprising the secondary battery. The secondary battery comprises: a negative electrode sheet and an electrolyte, where the negative electrode sheet comprises a silicon-carbon composite material and the silicon-carbon composite material has a three-dimensional network crosslinked pore structure; and the electrolyte comprises a carboxylate compound.