Anode Active Material Coating for Lithium Precipitation Control
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in improving cycle characteristics while maintaining input and output characteristics, particularly when using carbon materials as anode active materials, and when increasing the thickness or volume density of the anode active material layer, which can lead to lithium precipitation and reduced performance.
Innovation Solution
The use of an anode material with a carbon active layer coated with alkali metal or alkali earth metal salts, where the covering particles are formed on the surface of the anode active material to enhance intercalation and de-intercalation efficiency and chemical stability, preventing lithium precipitation and electrolyte decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the anode active material layer is increased to improve battery capacity, then the occupancy ratio of the anode active material layer is increased, but the current density of the anode is relatively increased causing lithium precipitation and reduced cycle characteristics
Solution Approach 1:
The patent applies local quality by creating a non-uniform thickness distribution of the anode active material layer. The layer has a first thickness in a first region and a second thickness different from the first thickness in a second region. This allows different regions to have optimized properties: thicker regions provide higher capacity while thinner regions maintain lower current density, preventing lithium precipitation and improving cycle characteristics.
2Quantity of substance
If the volume density of the anode active material layer is increased to obtain high battery capacity, then the battery capacity is improved, but the gaps where lithium ions move become small causing slow transfer rate and reduced input/output characteristics
Solution Approach 1:
The patent implements local quality by varying the thickness of the anode active material layer across different regions. Thinner regions provide larger gaps for lithium ion movement, ensuring fast transfer rates and good input/output characteristics, while thicker regions contribute to higher overall battery capacity. This spatial variation resolves the contradiction between capacity and productivity.
3Quantity of substance
If silicon or tin with high theoretical capacity is used as anode active material, then the battery capacity is highly improved, but the anode active material becomes highly activated causing electrolyte decomposition and reduced cycle characteristics
Solution Approach 1:
The patent applies local quality by using different anode active materials in different regions. High-capacity materials like silicon or tin are used in regions where their high activation can be managed, while other regions use materials with lower activation. This spatial differentiation allows the battery to achieve high overall capacity while maintaining good cycle characteristics through regions with lower reactivity.
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 approach improves the cycle characteristics and maintains input and output characteristics by facilitating smooth lithium ion transfer and reducing the reactivity of the anode active material, thereby extending battery life and performance.
Implementation Method 1
a secondary battery using intercalation and deintercalation of lithium for charge and discharge reaction
Implementation Method 2
the anode active material includes a carbon material and at least part of a surface is covered by a covering, the covering including at least one of an alkali metal salt and an alkali earth metal salt
Implementation Method 3
when the same electric capacity is charged and discharged, the current density of the anode is relatively increased. Therefore, in the anode, intercalation (insertion) and deintercalation (extraction) of lithium ions are not sufficiently generated
Data Source
AI summary
An anode and battery including the anode capable of improving the cycle characteristics while securing the input and output characteristics is provided. The battery includes a cathode, an anode, and an electrolytic solution. The anode includes an anode active material layer on an anode current collector, wherein the anode active material layer includes an anode active material capable of intercalating and deintercalating an electrode reactant, wherein a thickness of the anode active material layer ranges from 60 μm to 120 μm, and wherein the anode active material includes a carbon material and at least part of a surface is covered by a covering, the covering including at least one of an alkali metal salt and an alkali earth metal salt.