Silicon Columnar Anode Layer With Low Modulus for Stable Cycling
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in achieving compatibility between capacity and cycle characteristics, particularly with silicon negative electrodes, where the dissimilar metal element forms an intermetallic compound that limits the capacity provided to silicon.
Innovation Solution
A battery design featuring a negative electrode with a negative electrode active material layer composed of columnar silicon bodies and a Young's modulus of 25 GPa or less, which improves deformability, allowing for a larger contact area with the electrolyte layer, thereby maintaining a dense structure during charge and discharge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as negative electrode active material to increase capacity, then capacity is improved, but cycle characteristics deteriorate due to formation of intermetallic compounds with dissimilar metal elements
Solution Approach 1:
The patent removes dissimilar metal elements (such as copper, nickel, cobalt, manganese, zinc, and calcium) from the negative electrode active material composition. By extracting these harmful elements that form intermetallic compounds with silicon, the invention eliminates the root cause of poor cycle characteristics while preserving silicon's high capacity benefits.
Solution Approach 2:
The patent changes the compositional parameters of the negative electrode active material by strictly limiting or eliminating the presence of dissimilar metal elements. This parameter change prevents the formation of intermetallic compounds during charge-discharge cycles, thereby improving cycle stability while maintaining high silicon content for capacity.
2Stability of the object's composition
If Young's modulus of negative electrode active material layer is increased to improve structural stability, then stability is improved, but deformability decreases reducing contact area with electrolyte layer
Solution Approach 1:
The patent optimizes the Young's modulus parameter of the negative electrode active material layer to be within the range of 10-25 GPa. This parameter change achieves a balance between structural stability and deformability, allowing the material to maintain integrity while sufficiently deforming to ensure good contact with the electrolyte layer during charge-discharge cycles.
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
This configuration ensures compatibility between capacity and cycle characteristics by reducing gaps between columnar bodies and smoothing their surface, resulting in improved ion conductivity and maintaining a stable interface with the electrolyte layer.
Implementation Method 1
Young's modulus of the negative electrode active material layer is less than or equal to 25 GPa, which improves deformability, allowing for a larger contact area with the electrolyte layer
Data Source
AI summary
A battery according to an aspect of the present disclosure includes a positive electrode, a negative electrode, and an electrolyte layer located between the positive electrode and the negative electrode. The negative electrode includes a negative electrode current collector and a negative electrode active material layer located between the negative electrode current collector and the electrolyte layer. The negative electrode active material layer has a plurality of columnar bodies containing silicon as a primary component. Young's modulus of the negative electrode active material layer is less than or equal to 25 GPa.