Silicon Nanoparticle Grinding for Lithium Battery Anodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon nanoparticles in lithium secondary batteries undergo surface oxidation during grinding, leading to reduced battery performance and shortened cycle lifespan due to mechanical stress and volume changes, which existing methods fail to adequately address.
Innovation Solution
Mechanically grinding or crushing silicon particles in a secondary particle state formed by agglomerating crystalline and amorphous primary particles under dry or wet conditions to minimize surface oxidation, using a milling process with inert beads and a diluent to control particle size and oxidation, resulting in improved initial efficiency and lifespan characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If silicon particles are mechanically ground to reduce particle size, then the volume change during charging/discharging is reduced, but surface oxidation occurs forming an oxide coating layer
Solution Approach 1:
The patent applies inert atmosphere by conducting the mechanical grinding process in an inert gas environment (such as nitrogen or argon) to prevent surface oxidation of silicon particles. This resolves the contradiction by maintaining the reduced particle size benefit while eliminating the harmful oxidation effect through environmental control.
Solution Approach 2:
The patent extracts or removes the oxide coating layer that forms on silicon particle surfaces after mechanical grinding through chemical treatment processes. This allows the particle size reduction benefit to be maintained while removing the harmful oxidation byproduct.
2Volume of moving object
If silicon particles are reduced to nanoscale, then volume expansion is controlled, but the fraction of oxide coating layer volume increases reducing battery performance
Solution Approach 1:
The patent converts the harmful oxide coating layer into a beneficial component by controlling its formation and composition. The oxide layer is transformed from a performance-reducing defect into a protective or functional layer that can coexist with the nanoscale silicon structure without compromising battery performance.
Solution Approach 2:
The patent changes the parameters of the oxide coating layer through controlled oxidation processes, adjusting its thickness, composition, and crystalline structure. By modifying these parameters, the oxide layer transitions from a harmful element to a controlled component that does not negatively impact battery performance.
3Object-affected harmful factors
If existing coating methods are used to suppress oxide layer formation, then surface oxidation is reduced, but the process is not economically efficient and capacity is lower than theoretical
Solution Approach 1:
The patent applies self-service by allowing the silicon particles to undergo controlled oxidation during the mechanical grinding process itself, rather than requiring separate coating or protection steps. The grinding process that reduces particle size also naturally forms a thin oxide layer that is then managed through the same process, eliminating the need for additional manufacturing steps.
Solution Approach 2:
The patent merges the particle size reduction process with the oxide layer management process. By combining mechanical grinding, controlled oxidation, and oxide layer removal or modification into an integrated process sequence, the patent achieves oxide suppression without requiring separate economically intensive coating steps.
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 effectively reduces surface oxidation of silicon nanoparticles, enhancing the initial efficiency and cycle lifespan of lithium secondary batteries by maintaining a suitable particle size and surface area, thereby improving the battery's performance and longevity.
Implementation Method 1
mechanically grinding or crushing particulate silicon
Implementation Method 2
surfaces of the particles easily oxidized, which formed an oxide coating layer on the silicon particles
Implementation Method 3
when silicon absorbs and stores the maximum amount of lithium during charging, the silicon converts into Li4.4Si
Implementation Method 4
a volume of silicon expands about 4.12 folds a volume of silicon before the expansion
Implementation Method 5
Mechanical stress applied to silicon during the expansion generates cracks inside and on the surface of an electrode
Data Source
AI summary
The present invention relates to a production method for a negative electrode active material for a lithium secondary battery, and to a lithium secondary battery, and provides a production method for a lithium secondary battery negative electrode active material that is produced by mechanically grinding or crushing, in dry or wet conditions, particulate silicon, which is in a secondary particle state formed by agglomerating crystalline and amorphous silicon primary particles.