Silicon Tin Carbon Composite Negative Electrodes for Lithium Ion Batteries
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Solution Overview
Problem
Current negative electrode materials in lithium batteries face challenges with poor cycling efficiency due to structural changes and large volume expansions associated with lithium intercalation/alloying, particularly with materials like silicon and tin, which lead to decreased cycling performance and structural integrity issues.
Innovation Solution
The development of composite negative electrode compositions characterized by specific formulas such as SiwSnxMyCz, SiwZnxSnyCz, or CuwZnxSnyCz, where w, x, y, and z are weight percents, and M is a metal atom from a specific group, incorporating elemental tin, silicon, and carbon, which stabilize the structure through amorphous phases and alloy formation, enhancing cycling stability and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon or tin is used as negative electrode material to increase energy density, then energy density is improved, but cycling stability deteriorates due to large volume expansions and structural changes
Solution Approach 1:
The patent applies composite materials by combining silicon or tin with graphite and conductive carbon to form a composite negative electrode. The graphite and carbon components provide structural stability and accommodate volume changes, while the silicon or tin provides high capacity. This composite structure resolves the contradiction by maintaining cycling stability through the stable graphite matrix while achieving high energy density through the high-capacity silicon or tin phases.
Solution Approach 2:
The patent employs parameter changes by controlling the particle size, morphology, and composition ratios of the composite materials. By optimizing these parameters, the electrode can accommodate volume expansions during lithium intercalation while maintaining structural integrity. The specific parameter optimization allows the material to achieve both high energy density and good cycling stability.
2Reliability
If conventional graphite is used as negative electrode material to ensure good cycling properties, then cycling stability is maintained, but energy density decreases
Solution Approach 1:
The patent uses composite materials combining graphite with silicon or tin phases. The graphite provides the stable cycling properties and structural framework, while the silicon or tin phases contribute high capacity. This composite approach allows the electrode to achieve energy density superior to pure graphite while maintaining the cycling stability characteristic of graphite-based electrodes.
Solution Approach 2:
The patent merges the advantages of different materials by combining the structural stability of graphite with the high capacity of silicon or tin. The composite structure allows both materials to contribute their beneficial properties simultaneously, achieving both good cycling stability and high energy density in a single electrode system.
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
These composite materials achieve improved cycling stability and high energy density by stabilizing the structure during lithium uptake and release, reducing irreversible changes and maintaining performance over multiple cycles, thus addressing the limitations of existing materials.
Implementation Method 1
incorporating elemental tin, silicon, and carbon, which stabilize the structure through amorphous phases and alloy formation
Implementation Method 2
stabilize the structure during lithium uptake and release
Implementation Method 3
structural changes and large volume expansions associated with lithium intercalation/alloying
Data Source
AI summary
Compositions are described that can provide high energy density active materials for use in negative electrodes of lithium ion batteries. These materials generally comprise silicon and/or tin, and may further comprise carbon and/or zinc as well as other elements in appropriate embodiments. The active materials can have moderate volume changes upon cycling in a lithium ion battery.