SiOx-Mg Negative Electrode Composition for Early-Cycle Capacity Retention
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining early-cycle capacity and high-temperature storage performance due to the limitations of silicon-based negative electrode active materials.
Innovation Solution
A negative electrode for lithium secondary batteries is developed, incorporating a silicon oxide (SiOx) composite with magnesium (Mg) and optimizing the type and amount of conductive agents, including carbon nanotubes and carbon black, to enhance both capacity retention and high-temperature storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon oxide (SiOx) is used as negative electrode active material to improve theoretical capacity, then capacity is improved, but early-cycle capacity retention deteriorates
Solution Approach 1:
The patent uses a composite material consisting of silicon oxide (SiOx) combined with magnesium (Mg) and carbon (C). This composite structure allows the material to achieve high theoretical capacity from the silicon oxide while the magnesium and carbon components improve structural stability and reduce early-cycle capacity loss, thus resolving the contradiction between high capacity and good capacity retention.
2Quantity of substance
If silicon-based material is used to replace carbon-based material to increase capacity, then theoretical capacity is improved, but high-temperature storage performance deteriorates
Solution Approach 1:
The patent employs a composite material of SiOx-Mg-C that combines the high capacity advantage of silicon-based materials with the thermal stability benefits of magnesium and carbon. This composite structure maintains high theoretical capacity while improving resistance to high-temperature degradation, thus resolving the contradiction between capacity and high-temperature storage performance.
Solution Approach 2:
The patent optimizes the composition parameters of the composite material, specifically controlling the ratios of SiOx, Mg, and C components. By adjusting these compositional parameters, the material achieves both high capacity and improved high-temperature storage performance, resolving the contradiction through parameter optimization.
3Reliability
If conductive agents are increased to improve capacity retention, then early-cycle capacity is improved, but device complexity increases
Solution Approach 1:
The patent integrates conductive agents within the SiOx-Mg-C composite structure itself, rather than adding separate conductive agent components. The carbon component in the composite serves dual functions as both structural element and conductive pathway, simplifying the overall electrode composition while maintaining good capacity retention.
Data Source
AI summary
The present invention relates to a negative electrode for a lithium secondary battery and a lithium secondary battery including the negative electrode, wherein, since the negative electrode of the present invention includes a silicon oxide (SiOx, 0<x<2) composite containing magnesium (Mg) in a negative electrode active material and optimizes a type and an amount of a conductive agent, the lithium secondary battery including the negative electrode may improve a decrease in early-cycle capacity and high-temperature storage performance.