Silicon Oxide Negative Electrode Lithium Doping Method
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Solution Overview
Problem
Lithium secondary batteries using silicon oxide as a negative electrode active material face capacity retention ratio degradation due to uneven lithium distribution, leading to poor cycle properties.
Innovation Solution
A method of doping and dedoping lithium within specific current value and doped amount ranges to ensure uniform lithium distribution, optimizing the V-dQ/dV curve for improved capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium is doped into silicon oxide to increase lithium ion conductivity, then the lithium ion conductivity improves, but the lithium distribution becomes uneven and cycle property deteriorates
Solution Approach 1:
The patent applies preliminary action by performing a first charge at a limited capacity (up to 1.2 mAh/cm²) before normal charging. This preliminary charge uniformly distributes lithium ions into the silicon oxide particles, establishing a homogeneous Li-Si-O alloy structure that prevents subsequent uneven lithium distribution and maintains excellent cycle stability.
Solution Approach 2:
The patent changes the charging parameter by limiting the first charge capacity to a specific range (0.01-1.2 mAh/cm²). This parameter control ensures that lithium ions are uniformly distributed without excessive doping, maintaining both high lithium ion conductivity and uniform lithium distribution for superior cycle performance.
2Productivity
If high current density is used for lithium doping, then the doping efficiency increases, but the lithium distribution becomes more uneven and capacity retention decreases
Solution Approach 1:
The patent uses preliminary action by performing a controlled first charge at limited capacity before normal operation. This preliminary step ensures uniform lithium distribution even when higher current densities are subsequently applied, as the initial uniform distribution creates a stable foundation that prevents concentration gradients from developing.
Solution Approach 2:
The patent applies partial action by limiting the first charge to only a portion of the total possible capacity (up to 1.2 mAh/cm²). This partial charging is sufficient to achieve uniform lithium distribution without the harmful effects of excessive doping, optimizing both efficiency and uniformity.
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 method enhances the capacity retention ratio and cycle performance of lithium secondary batteries by ensuring uniform lithium distribution and phase transitions in the negative electrode.
Implementation Method 1
lithium was doped locally into silicon oxide... the lithium ion conductivity of silicon oxide is low before lithium is doped and becomes higher as the amount of doped lithium increases
Implementation Method 2
a method for doping and dedoping lithium for the first time after a negative electrode for a lithium secondary battery comprising silicon oxide as an active material is produced
Data Source
AI summary
The object of an exemplary embodiment of the invention is to provide a negative electrode having excellent cycle property. An exemplary embodiment of the invention a method for doping and dedoping lithium for the first time after a negative electrode for a lithium secondary battery comprising silicon oxide as an active material is produced, comprising doping the lithium within the following current value range (A) and within the following doped amount range (B); current value range (A): a range of a current value in which a doped amount in which only one peak appears at 1 V or less on the V-dQ/dV curve becomes maximum, wherein the V-dQ/dV curve represents a relationship between voltage V of the negative electrode with respect to a lithium reference electrode and dQ/dV that is a ratio of variation dQ of lithium dedoped amount Q in the negative electrode to variation dV of the voltage V, and doped amount range (B): a range of a doped amount in which only one peak appears at 1 V or less on the V-dQ/dV curve.