SiOx Negative Electrode and Al-Coated Positive Electrode for Li-Ion Battery
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Solution Overview
Problem
Lithium ion secondary batteries with silicon oxide (SiOx) as the negative electrode active material face challenges in maintaining capacity and cycle characteristics due to volume changes during charge and discharge, leading to deteriorated battery properties, especially when the SiOx content is increased beyond 10% by weight.
Innovation Solution
A lithium ion secondary battery design incorporating a positive electrode with a lithium cobalt oxide active material coated with an Al-containing oxide, which increases the charge resistance and restricts lithium deposition on the negative electrode, combined with a negative electrode containing SiOx (0.5≦x≦1.5) at a content of 10 mass % or more, to enhance cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the SiOx content in the negative electrode active material is increased to achieve high capacity, then the battery capacity increases, but the cycle characteristics deteriorate due to volume changes during charge and discharge
Solution Approach 1:
The patent applies parameter changes by precisely controlling the SiOx composition parameter (0.5≦x≦1.5) and its content (10 mass % or more but less than 50 mass %) in the negative electrode active material. This optimization balances the capacity enhancement from higher SiOx content with the structural stability needed for good cycle characteristics, resolving the contradiction between quantity and reliability.
Solution Approach 2:
The patent uses composite materials by combining SiOx with other negative electrode active materials to form a mixed composition. This composite approach allows the battery to achieve high capacity through SiOx while the other materials provide structural stability, thereby maintaining good cycle characteristics despite the volume changes associated with high SiOx content.
2Quantity of substance
If the SiOx content is increased beyond 10% by weight to achieve high capacity, then the battery capacity exceeds that of graphite-only electrodes, but the volume expansion during cycling causes remarkable drop in battery properties
Solution Approach 1:
The patent optimizes the SiOx composition parameter x within the range 0.5≦x≦1.5 and controls the SiOx content to be 10 mass % or more but less than 50 mass %. This precise parameter control ensures high capacity while maintaining composition stability during cycling, preventing the remarkable drop in battery properties that occurs with uncontrolled high SiOx content.
Solution Approach 2:
The patent applies local quality by creating a specific compositional distribution in the negative electrode where SiOx is distributed among other active materials rather than being uniformly concentrated. This local optimization allows regions with different compositions to handle the volume expansion differently, maintaining overall structural stability while achieving high capacity.
3Quantity of substance
If conventional SiOx structures are used to achieve high capacity, then more lithium ions can be inserted and desorbed, but the charge discharge cycle characteristics show remarkable deterioration
Solution Approach 1:
The patent changes the compositional parameters by specifying SiOx with 0.5≦x≦1.5 and controlling its content to 10 mass % or more but less than 50 mass % of the total negative electrode active material. This parameter optimization enables high lithium ion insertion and desorption capacity while maintaining stable charge discharge cycle characteristics, unlike conventional SiOx structures that show remarkable deterioration.
Solution Approach 2:
The patent employs composite materials by forming a negative electrode active material that combines SiOx with other materials in a specific composition ratio. This composite structure allows the SiOx to provide high lithium ion capacity while the other materials contribute to structural stability, thereby achieving both high capacity and good cycle characteristics simultaneously.
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 battery achieves a high capacity exceeding 1000 mAh/g and maintains excellent charge discharge cycle characteristics by preventing lithium deposition on the negative electrode, thus improving the battery's overall performance and stability.
Implementation Method 1
the positive electrode comprises a positive electrode material in which a surface of particles of a positive electrode active material is coated with an Al-containing oxide, wherein the Al-containing oxide has an average coating thickness of 5 to 50 nm
Implementation Method 2
Si or Sn or a material including such an element have been examined as a material capable of insertion and desorption of more amounts of lithium (Li) ions
Implementation Method 3
the positive electrode active material contained in the positive electrode material comprises a lithium cobalt oxide comprising Co and at least one kind of an element M1 selected from the group consisting of Mg, Zr, Ni, Mn, Ti and Al
Data Source
AI summary
There is provided a lithium ion secondary battery with a high capacity and having excellent cycle characteristics. The lithium ion secondary battery, including a positive electrode, a negative electrode, a separator and a nonaqueous electrolyte liquid. Here, the positive electrode comprises a positive electrode material in which a surface of particles of a positive electrode active material is coated with an Al-containing oxide. The Al-containing oxide has an average coating thickness of 5 to 50 nm. The positive electrode active material contained in the positive electrode material comprises a lithium cobalt oxide comprising Co and at least one kind of an element M1 selected from the group consisting of Mg, Zr, Ni, Mn, Ti and Al. The negative electrode comprises a material S including SiOx (0.5≦x≦1.5) as a negative electrode active material, wherein in 100 mass % of a total of the negative electrode active material included in the negative electrode, the materials S is included in the negative electrode active material at a content of 10 mass % or more.