Negative-Electrode Active Material With Composite Coating for Thermal Stability
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Solution Overview
Problem
Existing secondary batteries, such as lithium-ion batteries, face challenges in inhibiting heat generation during abnormal events like internal short circuits, where current techniques do not adequately address this issue.
Innovation Solution
A negative-electrode active material is developed with a core particle coated by a first layer of amorphous carbon or carbon nanotubes and a second layer of inorganic compounds like metal oxides, which improves thermal stability and prevents heat generation by forming a stable layer on the surface of graphite particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single-layer coating of inorganic oxide is applied on graphite particles, then thermal stability is improved, but heat generation during internal short circuit is not sufficiently inhibited
Solution Approach 1:
The patent applies a composite coating structure consisting of a carbon-containing layer and an inorganic oxide layer. The carbon-containing layer (amorphous carbon, carbon nanotubes, or conductive polymer) provides thermal stability and structural integrity, while the inorganic oxide layer (TiO2, Al2O3, SiO2, etc.) provides thermal insulation and chemical stability. This composite structure effectively inhibits heat generation during internal short circuits by combining the advantages of both material types, creating a multi-functional protective barrier that single-layer coatings cannot achieve.
2Reliability
If graphite particles are used as core material, then good intercalation performance is achieved, but surface stability and thermal resistance are insufficient
Solution Approach 1:
The patent employs a nested core-shell structure where the graphite core particle is coated with a carbon-containing layer, which is in turn coated with an inorganic oxide layer. This nested configuration preserves the excellent intercalation properties of the graphite core while progressively adding protective functions at each layer. The carbon-containing layer maintains electrical conductivity and structural integrity, while the outer inorganic oxide layer provides thermal insulation and chemical stability, thus solving the surface stability issue without compromising the core's intercalation performance.
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 configuration significantly reduces heat generation during internal short circuits, as demonstrated by lower battery resistance and temperature rise in tested batteries, effectively addressing the limitations of previous technologies.
Implementation Method 1
a second layer including at least one inorganic compound selected from an oxide, a phosphoric acid compound, a silicic acid compound, and a boric acid compound, and formed on the aforementioned first layer
Implementation Method 2
improves thermal stability and prevents heat generation by forming a stable layer on the surface of graphite particles
Implementation Method 3
a core particle including a material that intercalates and releases a metal ion
Data Source
AI summary
A negative-electrode active material for secondary batteries according to one aspect of the present invention comprises: core particles comprising a material which occludes and releases lithium metal; a first layer, which has been formed on the surface of each core particle; and a second layer, which has been formed on the first layer. The first layer comprises at least one substance selected from among amorphous carbon, carbon nanotubes, carbon nanofibers, and electroconductive polymers. The second layer comprises at least one inorganic compound selected from among oxides, phosphoric acid compounds, silicic acid compounds, and boric acid compounds.