Lithium-Doped SiOx Anode Composition for Initial Efficiency and Cycle Life
Find Innovative SolutionsGenerate Solutions
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, where specific lithium silicates are introduced through a pretreatment process to optimize the ratio of reversible to irreversible phases, improving energy density and battery stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Si-based material is used to improve energy density, then theoretical capacity increases to 3580 mAh/g, but volume expansion reaches ~400% causing deteriorated battery life
Solution Approach 1:
The patent uses SiOx material as a composite structure where silicon oxide forms a matrix that accommodates silicon particles. This composite approach allows the high capacity of silicon while the oxide matrix constrains volume expansion during lithiation/delithiation cycles, resolving the contradiction between capacity and stability.
Solution Approach 2:
The patent changes the chemical composition parameter by using SiOx instead of pure Si, and further optimizes by controlling the crystallinity parameter of the SiOx matrix. This parameter change reduces the volume expansion from 400% to a manageable level while maintaining high capacity.
2Duration of action of stationary object
If SiOx material is used to reduce volume expansion, then life characteristic improves, but initial coulombic efficiency deteriorates due to irreversible phase formation
Solution Approach 1:
The patent applies a Li pretreatment process before the battery's normal operation. This preliminary action pre-forms the irreversible Li2SiO3 phase during a separate treatment step, so that during subsequent cycling, less irreversible phase formation occurs, thereby improving initial coulombic efficiency while maintaining the long cycle life benefits of SiOx.
3Loss of energy
If Li pretreatment is applied to improve initial efficiency, then irreversible phase formation is reduced, but energy costs increase and capacity optimization becomes complex
Solution Approach 1:
The patent merges the Li pretreatment step with the existing battery manufacturing process by performing it during the electrode preparation stage. This integration combines multiple functions (pretreatment, electrode formation, and material activation) into a single process step, reducing overall process complexity while maintaining the efficiency benefits.
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 the initial efficiency and life characteristic of lithium secondary batteries by suppressing crystalline silicon growth and increasing the amorphous silicon content, leading to improved discharge capacity and capacity retention.
Implementation Method 1
a negative electrode for a lithium secondary battery, the negative electrode including: a current collector; and a negative electrode active material layer including the negative electrode active material
Implementation Method 2
improving a problem of deterioration of battery stability, a life characteristic, and the like due to expansion of silicon-based oxide particles caused by use of the silicon-based oxide as a negative electrode active material
Data Source
Figure 1
Figure 2~3
AI summary
Provided are a negative electrode active material including: negative electrode active material particles including: 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, wherein when a signal generated in a region of 200 to 600 cm-1 according to a Raman spectrum is subjected to deconvolution into three peaks, which are set to peak A, peak B, and peak C from lowest to highest of an absolute value of a wavenumber, the negative electrode active material particles satisfy Relation 1, a method of preparing the same, and a negative electrode and a lithium secondary battery including the negative electrode active material.