Lithium-Doped SiOx Anode Material for Stable High-Capacity Cycling
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Solution Overview
Problem
Conventional lithium secondary batteries using graphite active materials have low energy density and silicon-based materials suffer from battery life deterioration due to large volume expansion, while silicon oxide materials face challenges with initial coulombic efficiency and irreversible phase formation.
Innovation Solution
The use of lithium-doped silicon-based oxide negative electrode active materials with controlled crystallinity, specifically incorporating silicon oxide (SiOx) and lithium silicate phases, optimized through a pretreatment process to improve energy density, initial efficiency, and battery life by adjusting the ratio of reversible to irreversible phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based oxide material is used as negative electrode active material, then energy density is improved, but volume expansion occurs causing deterioration of battery stability and life characteristic
Solution Approach 1:
The patent applies parameter changes by controlling the crystallinity of silicon-based oxide particles through specific heat treatment conditions (temperature, time, atmosphere). By adjusting these parameters, the material achieves optimal balance between capacity and stability without requiring composite structures or additional components.
Solution Approach 2:
The patent creates a composite structure within the silicon-based oxide particles themselves, where crystalline and amorphous phases coexist in specific ratios. This internal composite architecture allows the material to simultaneously achieve high energy density from crystalline regions and volume expansion resistance from amorphous regions.
2Duration of action of stationary object
If silicon oxide material is used to reduce volume expansion, then battery life characteristic is improved, but initial coulombic efficiency deteriorates due to formation of irreversible phase
Solution Approach 1:
The patent uses parameter changes by precisely controlling the heat treatment conditions to achieve a specific crystallinity level in the silicon-based oxide. This parameter optimization allows the material to form beneficial irreversible phases during initial cycling while limiting excessive volume expansion, thereby improving initial coulombic efficiency without sacrificing battery life.
3Reliability
If Li pretreatment process is applied to improve initial efficiency, then initial coulombic efficiency is improved, but energy cost increases and capacity characteristic optimization becomes more complex
Solution Approach 1:
The patent applies preliminary action by incorporating Li doping during the material synthesis stage rather than requiring separate post-synthesis treatment steps. The Li pretreatment is integrated into the heat treatment process that already controls crystallinity, eliminating the need for additional processing steps and reducing overall process complexity while achieving improved initial coulombic efficiency.
4Reliability
If crystallinity of silicon-based oxide is increased to improve initial efficiency, then initial coulombic efficiency is improved, but volume expansion resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the heat treatment temperature and time to achieve a specific crystallinity level (controlled peak position in Raman spectrum). This precise parameter control ensures that enough crystalline phase forms to improve initial efficiency while sufficient amorphous phase remains to provide volume expansion resistance during cycling.
Solution Approach 2:
The patent creates an internal composite structure within the silicon-based oxide particles where crystalline and amorphous phases coexist in optimized proportions. The crystalline regions provide high capacity and improved initial efficiency, while the amorphous regions maintain structural integrity and resist volume expansion during charge-discharge cycles.
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
This approach enhances battery capacity, stability, and life characteristics by suppressing crystalline silicon growth and promoting amorphous silicon, thereby improving discharge capacity and maintaining efficiency over cycles.
Implementation Method 1
a silicon oxide (SiOx, 02SiO3, Li2Si2O5, and Li4SiO4 in at least a part of the silicon oxide
Implementation Method 2
by controlling crystallinity of the silicon-based oxide
Data Source
AI summary
Provided are a negative electrode active material which includes negative electrode active material particles which includes a silicon oxide (SiOx, 0<x≤2); and at least one lithium silicate selected from Li2SiO3, Li2Si2O5, and Li4SiO4 in at least a part of the silicon oxide. The negative electrode active material particles have a maximum peak position by a Raman spectrum of more than 460 cm−1 and less than 500 cm−1. Also provided are a method of preparing the same, and a negative electrode and a lithium secondary battery including the negative electrode active material.