Silicon-Carbon Anode Pore Network for Cycle-Stable High-Energy Batteries
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Solution Overview
Problem
Existing secondary batteries face challenges in achieving both excellent cycle performance and kinetic performance while increasing energy density, primarily due to the poor volume stability of silicon-based negative electrode materials and the continuous regeneration of the solid electrolyte interface film, which increases internal resistance.
Innovation Solution
A secondary battery design incorporating a silicon-carbon composite material with a three-dimensional network cross-linked pore structure and an electrolyte containing dimethyl carbonate, which enhances ion transport 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 the energy density of the battery is improved, but the volume stability deteriorates and cycle performance worsens
Solution Approach 1:
Silicon particles are embedded within the pores of carbon matrix particles, creating a nested structure where high-capacity silicon is contained within the stable carbon framework. This allows the silicon to expand and contract during cycling while being constrained by the carbon matrix, resolving the volume stability issue while maintaining high energy density.
Solution Approach 2:
The carbon matrix is designed with a three-dimensional network cross-linked pore structure that provides space for silicon particles and accommodates volume changes. The porous structure allows electrolyte penetration and ion transport while the cross-linked network provides mechanical stability, solving both the energy density and volume stability contradictions.
2Quantity of substance
If silicon-based negative electrode material is used to increase energy density, then the energy density of the battery is improved, but the cycle performance deteriorates
Solution Approach 1:
The nested structure of silicon particles within carbon matrix pores prevents silicon from detaching during cycling. The carbon matrix acts as a stable framework that maintains electrode integrity over many cycles, thereby improving cycle performance while preserving the high energy density contribution from silicon.
Solution Approach 2:
The invention uses a composite material system combining silicon and carbon in a specific architectural arrangement. The composite structure leverages the high capacity of silicon while the carbon component provides structural stability and conductivity, achieving both high energy density and excellent cycle performance.
3Device complexity
If conventional electrolyte composition is used, then the battery structure is simple, but the ion transport at active material/electrolyte interface is insufficient and internal resistance increases
Solution Approach 1:
The invention changes the chemical composition parameters of the electrolyte by introducing dimethyl carbonate and controlling its mass ratio. This parameter change improves the interfacial compatibility between electrolyte and silicon-carbon composite, enhancing ion transport kinetics and reducing polarization resistance without significantly complicating the overall battery structure.
4Quantity of substance
If high silicon content is loaded in the negative electrode, then the energy density is improved, but the volume change during charge and discharge increases
Solution Approach 1:
Silicon particles are nested within the pores of carbon matrix, allowing high silicon content to be loaded while the carbon matrix confines the silicon and prevents excessive volume expansion. The nested architecture enables the silicon to undergo volume changes within the constrained space of the carbon pores, maintaining electrode structural integrity.
Solution Approach 2:
The porous carbon matrix provides three-dimensional space that accommodates the volume expansion of silicon during lithiation. The pore structure acts as a buffer that absorbs volume changes, allowing high silicon content to be incorporated without causing detrimental volume effects on the overall electrode structure.
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 cycle performance and rate performance by stabilizing the volume change of silicon and facilitating efficient ion migration, thereby increasing the energy density of the battery.
Implementation Method 1
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
Implementation Method 2
dimethyl carbonate blended in the electrolyte may increase the reflux rate of the electrolyte during charge and discharge, promote ion transport at an active material/electrolyte interface
Implementation Method 3
effectively reduce the polarization resistance of the battery, thereby improving the cycle performance and rate performance of the battery
Data Source
AI summary
A secondary battery and an electrical device including the secondary battery. The secondary battery includes a negative electrode and an electrolyte. The negative electrode of the secondary battery includes a silicon-carbon composite material having a three-dimensional network cross-linked pore structure, and the electrolyte of the secondary battery includes dimethyl carbonate.