Silicon Oxide Negative Electrode Material for Lithium-Ion Batteries
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Solution Overview
Problem
Lithium-ion secondary batteries using silicon materials face challenges in achieving high cycle performance and initial efficiency due to the expansion and contraction of silicon active material particles, leading to electrolyte decomposition and reduced battery life.
Innovation Solution
A negative electrode material comprising silicon oxide (SiOx) with 0.5≤x≤1.6, containing Li2SiO3 and metal or ammonium ions, is developed, with a carbon coating and a binder to enhance conductivity and stability, and a method involving electrochemical modification to form lithium compounds within the silicon oxide, improving resistance to solvents and maintaining capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as a negative electrode active material to improve battery capacity, then the battery capacity increases significantly, but the silicon particles expand and contract during charging and discharging, leading to particle breakage and reduced cycle performance
Solution Approach 1:
The patent applies nesting by placing silicon particles inside a porous carbon matrix structure. The carbon matrix acts as a container that accommodates the silicon particles, allowing the silicon to expand and contract during lithium insertion/extraction without breaking. This nested configuration enables the high capacity of silicon while protecting against particle degradation, resolving the contradiction between capacity improvement and cycle performance maintenance.
Solution Approach 2:
The patent employs a porous carbon matrix that functions as a flexible shell surrounding the silicon particles. This carbon shell can deform elastically to accommodate the volume changes of silicon during charging and discharging cycles, preventing particle breakage while maintaining structural integrity. The flexible carbon shell thus enables both high capacity utilization and long cycle life.
2Quantity of substance
If silicon particles are used to increase battery capacity, then the initial efficiency improves, but the surface layer breaks easily and creates new surfaces that decompose the electrolyte, reducing cycle performance
Solution Approach 1:
The patent introduces a porous carbon matrix as an intermediary between the silicon particles and the electrolyte. This carbon matrix serves as a protective barrier that prevents direct contact between the silicon surface and the electrolyte, thereby eliminating the harmful electrolyte decomposition reaction. The intermediary carbon layer allows lithium ion transport while blocking the harmful chemical reactions, resolving the contradiction between capacity improvement and electrolyte stability.
Solution Approach 2:
The patent applies preliminary anti-action by pre-coating silicon particles with carbon and creating a porous carbon matrix structure before electrode assembly. This preliminary protective configuration prevents the surface breakage and electrolyte decomposition issues that would otherwise occur during silicon expansion and contraction. The pre-established carbon protective structure thus prevents harmful effects before they can occur during battery cycling.
3Quantity of substance
If the surface layer of silicon particles breaks during charging and discharging, then a new surface is created increasing reaction area, but this consumes electrolyte through decomposition reactions
Solution Approach 1:
The porous carbon matrix acts as an intermediary that provides a stable reaction surface for lithium insertion/extraction while preventing direct silicon-electrolyte contact. This intermediary structure maintains the necessary reaction area for high capacity without exposing fresh silicon surfaces to the electrolyte, thus preventing electrolyte decomposition and consumption while preserving the benefits of increased reaction area.
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 significantly reduces irreversible capacity, enhances resistance to organic and water solvents, and improves initial efficiency and cycle performance, leading to increased battery capacity and stability.
Implementation Method 1
a SiO2 component part destabilized with insertion and extraction of lithium
Implementation Method 2
a method involving electrochemical modification to form lithium compounds within the silicon oxide
Data Source
Figure 1~2
Figure 3
AI summary
The present invention is a negative electrode material for a non-aqueous electrolyte secondary battery, including negative electrode active material particles containing a silicon compound expressed by SiOx, where 0.5≤x≤1.6, the silicon compound containing in its interior a lithium compound and one or more ions selected from Group 1 metal ions, Group 2 metal ions, and substitutable ammonium ions. This negative electrode material for a non-aqueous electrolyte secondary battery can increase the battery capacity and improve the cycle performance and the battery initial efficiency.