Negative Electrode Coating Suppresses Lithium Dendrites
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face safety risks due to instability during high-temperature exposure and overcharge, leading to potential explosions and fires, as existing solutions either degrade battery performance or only delay heat generation and ignition without complete suppression.
Innovation Solution
A negative electrode active material comprising artificial graphite secondary particles with a carbon layer and a coating layer containing a compound like Cu3Si, which reacts with lithium at high temperatures to prevent needle-shaped lithium growth and suppress ignition, while maintaining battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flame retardant additive is added to the electrolyte solution or electrode active material to improve safety, then stability during high-temperature exposure is improved, but side reactions occur and battery performance such as cycle characteristics is degraded
Solution Approach 1:
A coating layer comprising a compound of Formula 1 (where X is a metal having no reactivity with lithium, Y is a metal or semi-metal having reactivity with lithium, and a and b are integers satisfying 1≤a≤5 and 1≤b≤3) is formed on the negative electrode active material particles. This coating layer acts as an intermediary that reacts with lithium at high temperatures to prevent needle-shaped lithium growth and suppress ignition, while not degrading battery performance such as cycle characteristics.
Solution Approach 2:
The invention changes the chemical composition parameters of the negative electrode active material by incorporating a specific compound (XaYb) where the metal-metal bond dissociation energy is controlled to be 160 kJ/mol to 250 kJ/mol. This parameter optimization allows the material to remain stable during normal operation but react effectively at high temperatures to suppress ignition and explosion risks.
2Reliability
If safety devices such as protection circuit module, PTC device, or current interruption device are installed to suppress overcharge, then overcharge stability is improved, but device complexity increases
Solution Approach 1:
The negative electrode active material itself provides safety functions through its intrinsic chemical properties. The coating layer comprising XaYb automatically reacts with lithium at high temperatures and during overcharge conditions to prevent needle-shaped lithium growth and suppress ignition, eliminating the need for external safety devices and reducing overall system complexity.
3Object-affected harmful factors
If the separator is coated with inorganic particles to prevent internal short circuit, then internal short circuit risk is reduced, but energy stored in the battery is not removed and heat generation or ignition is only delayed not completely suppressed
Solution Approach 1:
The invention converts the potential harm of high temperature and overcharge conditions into a beneficial protective mechanism. The coating layer comprising XaYb remains stable during normal operation but reacts with lithium at high temperatures to prevent needle-shaped lithium growth and suppress ignition, effectively converting dangerous conditions into a protective response that eliminates rather than merely delays heat generation and ignition risks.
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 solution effectively suppresses ignition and explosion risks during high-temperature exposure and overcharge without degrading battery performance, ensuring improved stability and capacity retention.
Implementation Method 1
a coating layer which is formed on the negative electrode active material particle and includes a compound represented by Formula 1... Y is a metal or semi-metal having reactivity with lithium... which reacts with lithium at high temperatures to prevent needle-shaped lithium growth and suppress ignition
Implementation Method 2
the compound represented by Formula 1 may have a bond dissociation energy between X and Y of 160 kJ/mol to 250 kJ/mol
Data Source
AI summary
A negative electrode active material which may dramatically improve stability of a battery while not degrading battery performance such as cycle characteristics, and a negative electrode and a lithium secondary battery which include the same, wherein the negative electrode active material includes negative electrode active material particles which include artificial graphite in the form of a secondary particle and a carbon layer formed on the surface of the artificial graphite, and a coating layer which is formed on the negative electrode active material particle and includes a compound represented by Formula 1.