Separator Spacer Layout for Lithium Metal Battery Expansion Control
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Solution Overview
Problem
Lithium secondary batteries face challenges with electrode expansion during charging and limited cycle characteristics, particularly in the vicinity of the negative electrode.
Innovation Solution
A lithium secondary battery design featuring a separator with a base layer and composite material layer, incorporating a spacer with specific dimensions and composition to maintain a controlled space between the positive and negative electrodes, utilizing a polymer and inorganic particles to enhance electrolyte circulation and suppress expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a spacer is provided between the positive electrode and the separator to accommodate lithium metal, then the capacity is improved, but the electrode group expansion during charging increases
Solution Approach 1:
The spacer is positioned locally between the positive electrode and separator at specific locations where lithium metal accommodation is needed, rather than uniformly throughout the battery structure. This localized approach allows lithium metal deposition without causing overall electrode group expansion
Solution Approach 2:
The spacer acts as an intermediary structure between the positive electrode and separator, creating a controlled space for lithium metal accommodation. This intermediary element manages the volume changes during charging by providing a dedicated accommodation zone that prevents expansion of the main electrode group
2Quantity of substance
If the spacer width is increased to improve lithium metal accommodation, then the capacity is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The spacer width is optimized to a specific range (0.01 mm or more but controlled within tight tolerances) to balance lithium metal accommodation capacity with manufacturability. This parameter optimization allows sufficient lithium metal space while maintaining compatibility with standard manufacturing precision capabilities
3Reliability
If the shortest distance from spacer to outer edge is increased to improve electrode stability, then the cycle characteristic is improved, but the lithium metal accommodation space is reduced
Solution Approach 1:
The spacer is positioned with a controlled shortest distance (less than 1.5 mm) from the outer edge to create an optimal balance between electrode stability and lithium metal accommodation space. This localized positioning ensures sufficient edge distance for structural integrity while maximizing the available accommodation volume
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 design effectively reduces electrode group expansion and improves cycle characteristics by maintaining a stable electrode structure and electrolyte flow, thereby enhancing battery performance.
Implementation Method 1
a non-aqueous electrolyte having lithium-ion conductivity
Implementation Method 2
lithium metal is deposited on the negative electrode during charging, and this lithium metal dissolves in the non-aqueous electrolyte during discharging
Data Source
AI summary
A disclosed lithium secondary battery includes a positive electrode, a negative electrode, a separator (50) disposed between the positive electrode and the negative electrode, a spacer (53) disposed on the separator (50), and a non-aqueous electrolyte having lithium-ion conductivity. The negative electrode is an electrode onto which lithium metal is deposited during charging and from which lithium metal dissolves during discharging. The separator (50) includes a base layer (51) and a composite material layer (52). In a plan view, the shortest distance from any point on the spacer (53) to the outer edge of the spacer (53) is less than 1.5 mm, and the spacer (53) has a width of 0.01 mm or more. The composite material layer (52) contains a polymer and inorganic particles.