Tin-Composite Negative Active Material for Lithium Ion Batteries
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Solution Overview
Problem
Lithium ion batteries using tin-negative-active materials face challenges due to high volume change during charging and discharging, leading to electrode peeling and reduced capacity and cycling performance.
Innovation Solution
A method involving mixing a carbon material, an organic polymer, and a Sn-containing compound with water, adding a complexing agent and reducing agent to form a reaction product, which is then filtered, washed, and dried to create a negative active material, optionally with sintering to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If tin materials are used as negative active material, then specific capacity is improved, but volume change during charging and discharging increases causing electrode peeling and reduced cycling performance
Solution Approach 1:
The patent uses composite materials by combining tin particles with carbon materials (such as graphite or amorphous carbon) to form a composite negative active material. The carbon component provides structural stability and accommodates the volume expansion of tin during lithiation, while the tin component provides high specific capacity. This composite structure prevents electrode peeling and maintains cycling performance while retaining the high capacity benefit of tin.
2Quantity of substance
If tin materials are used as negative active material, then specific capacity is improved, but electrode peeling and powderizing occur reducing cycling performance
Solution Approach 1:
The patent employs a carbon-based shell or coating around tin particles that acts as a flexible protective layer. This shell accommodates the volume expansion and contraction of tin during charging and discharging cycles without breaking, preventing electrode peeling and powderizing. The flexible carbon shell maintains the structural integrity of the electrode over multiple cycles, ensuring reliable cycling performance while preserving the high specific capacity of tin.
3Quantity of substance
If tin materials are used as negative active material, then theoretic capacity increases, but volume change causes capacity drop
Solution Approach 1:
The patent changes the physical and chemical parameters of the tin material by controlling particle size, morphology, and composition during synthesis. By optimizing these parameters, the tin-based negative active material achieves both high theoretic capacity and good capacity retention. The controlled parameters enable the material to accommodate volume changes better, maintaining structural stability and capacity retention over cycling.
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 method improves the specific capacity and cycling performance of lithium ion batteries by stabilizing the tin-negative-active material, reducing volume change and maintaining high capacity retention over multiple cycles.
Implementation Method 1
A complexing agent may be added to the mixed solution system, optionally under constant stirring to form an intermediate solution
Implementation Method 2
A reducing agent may be added to the intermediate solution to form a reaction product
Data Source
AI summary
Methods of preparing negative active materials and negative active materials are provided herein. The preparation methods include: A) mixing a carbon material, an organic polymer, a Sn-containing compound—optionally with water—to obtain a mixed solution system; B) adding a complexing agent into the mixed solution system obtained in step A optionally while stirring to form an intermediate solution; C) adding a reducing agent into the intermediate solution obtained in step B to a reaction product; D) optionally filtering, washing and then drying the reaction product to obtain the negative active material.