Silicon-Carbon Anode Electrolyte for Low-Gas Lithium-Ion Cycling
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Solution Overview
Problem
Silicon-based materials in lithium-ion batteries experience significant volume changes during charge and discharge, leading to deformation, cracking, increased side reactions, and safety issues such as gas and heat generation, which affect kinetic performance and cycling stability.
Innovation Solution
Incorporating a silicon-carbon material with a specific sphericity of 0.5-1 and a sulfur-containing heterocyclic compound in the electrolyte solution, along with a carboxylate ester solvent, to form a uniform solid electrolyte interface membrane, thereby stabilizing the silicon-based negative electrode and enhancing thermal safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used in the negative electrode to increase energy density, then the battery capacity increases, but the volume expansion and cracking occur during charge and discharge
Solution Approach 1:
The patent embeds silicon-based materials within a porous carbon substrate structure, creating a nested configuration where silicon particles are contained within the carbon matrix. This nesting approach allows the silicon to expand and contract during lithium insertion/extraction while being constrained by the surrounding carbon structure, preventing electrode deformation and cracking while maintaining high lithium ion storage capacity.
Solution Approach 2:
The patent employs a porous carbon substrate with controlled pore structure to host silicon-based materials. The porous structure provides sufficient space for silicon volume expansion during charging while maintaining structural integrity. The pores act as buffer zones that accommodate the expansion stress, preventing cracking and maintaining electrode stability throughout cycling.
2Quantity of substance
If silicon-based materials are used to increase capacity, then energy density improves, but side reactions increase leading to gas and heat generation
Solution Approach 1:
The patent introduces a sulfur-containing heterocyclic compound as an intermediary substance in the electrolyte that mediates the interaction between silicon-based materials and the electrolyte solution. This compound facilitates the formation of a stable protective film on the silicon surface, which acts as a barrier to prevent direct contact between silicon and electrolyte, thereby suppressing side reactions, gas evolution, and heat generation while allowing lithium ion transport.
3Reliability
If conventional electrolyte composition is used, then basic battery function is maintained, but kinetic performance and cycling stability are insufficient
Solution Approach 1:
The patent modifies the electrolyte composition by incorporating specific ratios of carboxylate ester solvent and sulfur-containing heterocyclic compound. This parameter change in the electrolyte formulation enables the formation of an optimized solid electrolyte interface membrane that simultaneously improves lithium ion transport kinetics and enhances cycling stability. The specific composition parameters create a balanced interface layer that facilitates fast ion transfer while maintaining structural integrity over extended cycling.
4Quantity of substance
If silicon-based materials are used to increase capacity, then energy density improves, but SEI membrane thickening occurs increasing internal resistance
Solution Approach 1:
The sulfur-containing heterocyclic compound acts as an intermediary that directs the formation of a thin and uniform SEI membrane on the silicon-based material surface. This intermediary substance ensures that the SEI layer forms preferentially from the heterocyclic compound rather than from continuous electrolyte decomposition, resulting in a thinner, more stable interface membrane that maintains low internal resistance while protecting the silicon from further degradation.
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 improves kinetic performance, cycling stability, and thermal safety by reducing volume expansion and suppressing gas generation, resulting in a more stable and safer lithium-ion battery.
Implementation Method 1
the silicon-carbon material comprises a porous carbon substrate and a silicon material distributed within pores of the porous carbon substrate
Implementation Method 2
by adding a carboxylate ester solvent and a sulfur-containing heterocyclic compound to an electrolyte solution... to form a uniform solid electrolyte interface membrane
Data Source
AI summary
The present disclosure relates to a lithium-ion secondary battery. The battery comprises a negative electrode plate, comprising a negative electrode active material which comprises a silicon-carbon material. the silicon-carbon material comprises a porous carbon substrate and a silicon material distributed within pores of the porous carbon substrate; and the sphericity of the silicon-carbon material is denoted as Q, with the sphericity Q being 0.5-1. the electrolyte solution comprises a carboxylate ester solvent and a sulfur-containing heterocyclic compound, wherein the mass percentages of the carboxylate ester solvent and the sulfur-containing heterocyclic compound are denoted as E % and S %, respectively, based on the total mass of the electrolyte solution; and E and S satisfy 10≤E/S≤100, which can enable lithium-ion batteries to have a good kinetic performance, a higher energy density, a better cycling stability and a better thermal safety performance.