Silicon Active Material Composition for High-Capacity Battery Cycling
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Solution Overview
Problem
Existing secondary batteries have insufficient battery characteristics, such as energy density and cyclability, despite efforts to improve them.
Innovation Solution
An active material comprising silicon, oxygen, boron, phosphorus, an alkali metal element, a transition element, and an alkaline earth metal element, with specific content ranges, is used in the negative electrode of a secondary battery. This active material is manufactured through a process involving silicate glass, a carbon source, and a carbon reduction treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon oxide is used as negative electrode active material, then battery capacity is improved, but cyclability characteristic deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the active material by incorporating multiple elements (Si, P, B, Li, Mg, Al, Ti, Zn) in specific ratios. The silicon content is controlled at 5-90 wt%, phosphorus at 1-30 wt%, boron at 1-20 wt%, with other elements in smaller amounts. This parameter optimization resolves the contradiction by achieving both high capacity and good cyclability.
Solution Approach 2:
The invention creates a composite active material combining silicon-based compounds with phosphorus, boron, and other metal elements. This composite structure leverages the high capacity of silicon while the other elements contribute to structural stability and cyclability, resolving the contradiction between capacity and reliability.
2Reliability
If different elements are added to silicon oxide to improve characteristics, then battery characteristic is improved, but manufacturing complexity increases
Solution Approach 1:
The invention merges multiple element additions into a single comprehensive composition formula. Instead of separately adding each element through different processes, the patent specifies a unified compositional range (Si: 5-90 wt%, P: 1-30 wt%, B: 1-20 wt%, plus other elements) that can be achieved through integrated manufacturing, reducing complexity while maintaining improved characteristics.
3Quantity of substance
If pyroxene silicic acid compound and reduced tin oxide are used for high-capacity applications, then battery capacity is improved, but manufacturing process complexity increases
Solution Approach 1:
The invention simplifies the manufacturing approach by defining a compositional parameter range rather than requiring specific complex materials like pyroxene silicic acid compound or reduced tin oxide. The specified ranges (Si: 5-90 wt%, P: 1-30 wt%, B: 1-20 wt%) provide flexibility in material selection while achieving high capacity, reducing manufacturing process complexity.
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 use of this active material in the secondary battery significantly enhances its battery characteristics, including charge capacity, discharge capacity, and cyclability, leading to a superior overall battery performance.
Implementation Method 1
heating the mixture to thereby manufacture an active material including silicon, oxygen, the first element, the second element, and the third element as constituent elements
Data Source
AI summary
An active material includes, as constituent elements, silicon, oxygen, a first element, a second element, and a third element. The first element includes boron, phosphorus, or both. The second element includes at least one of an alkali metal element, a transition element, or a typical element. The typical element excludes silicon, oxygen, boron, phosphorus, an alkali metal element, and an alkaline earth metal element. The third element includes an alkaline earth metal element. The content of silicon with respect to all the constituent elements excluding oxygen and carbon is 60 at % or greater and 98 at % or less. The content of the first element with respect to all the constituent elements excluding oxygen and carbon is 1 at % or greater and 25 at % or less. The content of the second element with respect to all the constituent elements excluding oxygen and carbon is 1 at % or greater and 34 at % or less. The content of the third element with respect to all the constituent elements excluding oxygen and carbon is 0 at % or greater and 6 at % or less. A first peak is detected in an XPS spectrum of Si2p relating to the active material. The XPS spectrum of Si2p is measured using X-ray photoelectron spectroscopy (XPS). The first peak includes an apex within a range of a binding energy of 102 eV or greater and 105 eV or less, and a shoulder on a smaller binding energy side of the apex. A second peak is detected in a Raman spectrum relating to the active material. The Raman spectrum is measured using Raman spectroscopy. The second peak includes an apex within a range of a Raman shift of 435 cm−1 or greater and 465 cm−1 or less.