Metal Silicate Negative Electrode Gradient for Capacity and Cyclability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing negative electrodes for secondary batteries face challenges in achieving high capacity and cyclability due to Li loss and cracking, which are exacerbated by the introduction of magnesium, leading to decreased discharge capacity.
Innovation Solution
A negative electrode active material with a specific distribution of metal silicate, including alkaline earth, alkali, transition, or amphoteric metal elements, is designed with a 1:3:5 sectional area ratio to optimize metal element abundance, reducing reactivity and enhancing lithium insertability and extractability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnesium is introduced into the negative electrode active material particle to suppress Li loss and cracking, then cyclability characteristic is improved, but discharge capacity decreases
Solution Approach 1:
The patent applies local quality by creating a gradient distribution of metal silicate where the abundance of metal element varies across different regions of the negative electrode active material particle. Specifically, the surface part has higher metal element abundance than the middle part, which in turn has higher abundance than the center part. This spatial variation in composition allows the surface to provide protective functions (suppressing Li loss and cracking) while the center maintains high lithium content for discharge capacity, thus resolving the contradiction between improved cyclability and maintained capacity.
2Reliability
If metal silicate is uniformly distributed in the negative electrode active material, then Li loss is suppressed, but lithium insertability and extractability are reduced
Solution Approach 1:
The patent implements local quality by establishing a non-uniform distribution of metal silicate with a specific gradient pattern. The surface part contains the highest abundance of metal element to effectively suppress Li loss, the middle part has intermediate abundance to provide transition, and the center part has the lowest abundance to maximize lithium insertability and extractability. This localized variation in material properties allows simultaneous achievement of Li loss suppression and high lithium reversibility.
Solution Approach 2:
The patent applies parameter changes by controlling the abundance of metal element as a continuous variable that varies across different regions of the particle. By adjusting the metal element abundance parameter from high at the surface to low at the center, the patent optimizes both protective and functional properties. The specific ratio relationship (surface > middle > center) represents a controlled parameter gradient that balances competing requirements.
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 optimized distribution of metal silicate in the negative electrode active material improves physical durability, suppresses electrolyte decomposition, and maintains high energy density by balancing surface reactivity and central lithium accessibility.
Implementation Method 1
a lithium (Li)-trapping effect may be caused by oxygen, resulting in a decrease in an amount of Li that is extractable upon discharging
Implementation Method 2
large expansion of the negative electrode active material particle upon charging can cause a crack in the negative electrode active material particle
Data Source
AI summary
A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The negative electrode includes a negative electrode active material. The negative electrode active material includes a metal silicate. The metal silicate includes a metal element, silicon, and oxygen as constituent elements. The negative electrode active material includes a center part, a surface part, and a middle part. A ratio among a sectional area of the center part, a sectional area of the middle part, and a sectional area of the surface part in a section of the negative electrode active material is set to 1:3:5 thereby an abundance of the metal element in the middle part is greater than an abundance of the metal element in the center part, and an abundance of the metal element in the surface part is greater than the abundance of the metal element in the middle part.