Silicon Oxide Anode Active Material for Secondary Battery
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Solution Overview
Problem
Lithium ion secondary batteries using silicon-based materials as negative electrode active materials face challenges with low initial efficiency and discharge capacity retention due to the formation of irreversible components and cycle degradation when pre-doped with Li or Mg.
Innovation Solution
A negative electrode active material comprising a mixture of first silicon oxide powder doped with alkali or alkaline earth metals and undoped second silicon oxide powder, with the addition of a carbon material, to improve initial efficiency and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon oxide powder pre-doped with Li or Mg is used as negative electrode active material, then initial efficiency improves, but discharge capacity reduces or cycle characteristics degrade
Solution Approach 1:
The negative electrode active material is segmented into two distinct components: first silicon oxide powder (pre-doped with Li or Mg) and second silicon oxide powder (undoped). This segmentation allows each component to fulfill different functions - the doped portion provides high initial efficiency while the undoped portion maintains discharge capacity and cycle characteristics, resolving the contradiction between initial efficiency and discharge capacity retention.
2Quantity of substance
If silicon-based material is used as negative electrode material, then energy density improves, but initial efficiency becomes lower compared to graphite
Solution Approach 1:
The invention creates a composite negative electrode active material combining two types of silicon oxide powder with different properties. The first silicon oxide powder (doped) contributes to high initial efficiency, while the second silicon oxide powder (undoped) contributes to high energy density. This composite approach allows the electrode to achieve both high initial efficiency and high energy density simultaneously, resolving the contradiction between these two parameters.
3Quantity of substance
If silicon-based material is used as negative electrode material, then energy density improves, but discharge capacity retention degrades due to cycle degradation
Solution Approach 1:
By segmenting the negative electrode active material into doped and undoped silicon oxide components, the invention enables the undoped second silicon oxide powder to maintain structural stability during cycling, thereby preserving discharge capacity retention over multiple cycles while the doped first silicon oxide powder provides high energy density.
Data Source
AI summary
A negative electrode active material for a secondary battery for achieving high initial efficiency and improved discharge capacity and capacity retention. The negative electrode active material for a secondary battery includes first silicon oxide powder particles doped with at least one of alkali metal or alkaline earth metal, and second silicon oxide powder particles, which are not doped, wherein the second silicon oxide powder particles are amorphous. A negative electrode and a secondary battery including the negative electrode active material are also disclosed.