Sodium Titanium Oxide-Coated Anode Material for Stable SEI
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Sodium ion batteries suffer from a sharp decline in battery life due to the consumption of sodium ions by side reactions forming a solid electrolyte interface (SEI) during charging/discharging, leading to increased internal impedance.
Innovation Solution
An active material for the negative electrode comprising a carbon core material coated with a first ion-conducting modification layer of sodium titanium oxide, optionally enhanced with a second ion-conducting modification layer of lithium titanium oxide, to promote sodium ion diffusion and isolate the core from the electrolyte, reducing SEI formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If sodium ion batteries use conventional negative electrodes during charging/discharging, then battery operation is enabled, but sodium ions are consumed by side reactions forming SEI, resulting in sharp decline in battery life
Solution Approach 1:
The patent introduces an artificial solid electrolyte interface layer as an intermediary between the negative electrode and the electrolyte. This artificial SEI layer acts as a mediator that prevents direct contact between the electrolyte and negative electrode, thereby blocking the harmful side reactions that consume sodium ions while still allowing ionic transport, thus resolving the contradiction between enabling battery operation and preventing sodium ion consumption
Solution Approach 2:
The patent applies preliminary action by pre-forming a stable solid electrolyte interface layer on the negative electrode before actual battery operation begins. This preliminary SEI layer is formed under controlled conditions to ensure stability and low sodium ion consumption, preventing the formation of unstable SEI layers during subsequent charging/discharging cycles that would otherwise consume sodium ions and reduce battery life
2Reliability
If SEI layer forms during charging/discharging, then battery operation is maintained, but the SEI layer thickens causing internal impedance to continue rising, affecting electrical performance
Solution Approach 1:
The artificial solid electrolyte interface layer serves as an intermediary that provides a stable, controlled interface between the electrolyte and negative electrode. This intermediary layer prevents uncontrolled SEI formation and thickening that would increase internal impedance, while maintaining reliable ionic transport for electrical performance
Solution Approach 2:
The patent applies parameter changes by controlling the composition, thickness, and structure of the solid electrolyte interface layer to optimize its properties. By adjusting parameters such as the ratio of artificial SEI layer to negative electrode material and controlling formation conditions, the patent achieves a stable SEI layer with low and stable internal impedance while maintaining reliable electrical performance
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 proposed active material enhances sodium ion battery cycle life by minimizing sodium ion consumption and SEI formation, maintaining high capacitance retention over multiple cycles.
Implementation Method 1
promote sodium ion diffusion
Implementation Method 2
isolate the core from the electrolyte
Data Source
AI summary
An active material for negative electrode and a sodium ion battery are provided. The active material for negative electrode includes a core material and a first ion-conducting modification layer. The core material is a carbon material. The first ion-conducting modification layer is disposed on a surface of the core material. A material of the first ion-conducting modification layer includes sodium titanium oxide.