Silicon Nanoparticle Negative Electrode Material for Secondary Batteries
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Solution Overview
Problem
Silicon-based negative electrode materials for secondary batteries face challenges with rapid deterioration due to large volume changes during charge/discharge cycles, leading to poor initial efficiency and cycle characteristics, making them unsuitable for long-term use in high-energy density applications.
Innovation Solution
A negative electrode material comprising a matrix with silicon nanoparticles and doping elements like alkali metals or post-transition metals, embedded in a silicon oxide matrix with residual compressive stress, which enhances mechanical and electrochemical properties by maintaining composition uniformity and reducing volume expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used as negative electrode material to achieve high energy density, then the battery capacity increases, but the initial efficiency and cycle characteristics deteriorate due to large volume change during charge/discharge cycles
Solution Approach 1:
The silicon is divided into nanoparticle form with average diameter of 10 nm to 50 nm, which segments the bulk silicon structure into smaller units that can better accommodate volume changes during lithiation and delithiation, reducing the overall mechanical stress and preventing particle detachment
Solution Approach 2:
The patent creates a composite structure where silicon nanoparticles are embedded in a matrix containing silicon oxide and doping elements. This composite material combines the high capacity of silicon with the structural stability of silicon oxide and the stress-relief properties of the doped matrix, resolving the contradiction between high capacity and cycle stability
2Stability of the object's composition
If silicon oxide is used as negative electrode material, then the structural stability improves, but lithium is lost by irreversible products such as lithium silicate or lithium oxide and initial charge/discharge efficiency decreases
Solution Approach 1:
The patent applies local quality by creating regions with different compositions and functions: silicon-rich regions provide high capacity, while silicon oxide-rich regions provide structural stability. The doping elements are locally distributed to specifically address stress management, allowing each region to perform its optimized function without compromising the overall performance
3Stability of the object's composition
If nanosizing silicon into wire or compositing with carbon material is performed to solve silicon problems, then the volume change is reduced, but the initial charge/discharge efficiency and high rate characteristics remain poor
Solution Approach 1:
The patent changes multiple parameters simultaneously: the silicon particle size (10-50 nm), the composition ratio of silicon to silicon oxide, and the types/concentrations of doping elements. These parameter changes work synergistically to achieve both good volume control and high initial efficiency, overcoming the limitations of previous single-parameter approaches
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 improves the capacity retention rate and initial efficiency of silicon-based negative electrodes, enabling them to maintain high discharge capacity and stability over multiple cycles, suitable for commercialization in energy storage devices.
Implementation Method 1
a negative electrode material for a secondary battery including: a matrix including silicon (Si), one or more doping elements (D) selected from the group consisting of alkali metals, alkaline earth metals, and post transition metals, and oxygen (O)
Implementation Method 2
when particulate silicon is used as a negative electrode material, battery characteristics are rapidly deteriorated by insulation, particle desorption, increased contact resistance
Implementation Method 3
A negative electrode material comprising a matrix with silicon nanoparticles and doping elements like alkali metals or post-transition metals, embedded in a silicon oxide matrix with residual compressive stress, which enhances mechanical and electrochemical properties by maintaining composition uniformity and reducing volume expansion
Data Source
AI summary
A negative electrode material for a secondary battery including: a matrix including silicon (Si), one or more doping elements (D) selected from the group consisting of alkali metals, alkaline earth metals, and post transition metals, and oxygen (O), based on an element component; and silicon nanoparticles dispersed and embedded in the matrix, wherein the negative electrode material has composition uniformity, and a ratio (A1/A2) between an area of a first peak (A1) and an area of a second peak (A2) satisfying 0.8 to 6, a diffraction angle 2θ being positioned in a range of 10° to 27.4° in the first peak and being positioned in a range of 28±0.5° in the second peak, in an X-ray diffraction pattern using a CuKα ray.