Assembled Battery Spacer Rib Design for Electrodeposition Control
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Solution Overview
Problem
Assembled batteries with wound electrode bodies and spacers having rib portions are prone to micro short-circuits due to electrodeposition of charge carriers, which is exacerbated by variations in inter-electrode distance and localized current concentration.
Innovation Solution
The battery design incorporates a flat wound electrode body with a fixing member positioned in a moderation region, where no pressing force is actively exerted, to suppress electrodeposition by maintaining a consistent inter-electrode distance and reducing localized pressure, while spacers with rib portions provide effective cooling and compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If spacers with rib portions are combined with wound electrode bodies, then cooling efficiency is improved, but electrodeposition occurs leading to micro short-circuits
Solution Approach 1:
The spacer is designed with differentiated regions: a pressing region with rib portions that apply compression force to improve cooling, and a moderation region without pressing that prevents electrodeposition. This local differentiation allows the same spacer to simultaneously achieve both cooling efficiency and reliability by applying pressure only where thermally beneficial and avoiding it where electrochemical stability is needed.
2Stability of the object's composition
If the fixing member is positioned in the pressing region, then structural stability is improved, but electrodeposition is exacerbated
Solution Approach 1:
The moderation region acts as an intermediary zone that mediates between the structural requirements of the pressing region and the electrochemical stability requirements. By positioning the fixing member in this intermediate moderation region rather than directly in the pressing region, the design allows structural stability to be achieved while avoiding the harmful concentration of compressive stress that would cause electrodeposition.
3Productivity
If compression force is applied to maintain constant inter-electrode distance, then battery performance is improved, but localized current concentration increases
Solution Approach 1:
The spacer is segmented into functionally distinct pressing regions and moderation regions. The pressing regions provide necessary compression to maintain constant inter-electrode distance and improve battery performance, while the moderation regions segment the compression distribution to avoid localized current concentration by providing zones where compressive stress is reduced or absent.
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 effectively suppresses electrodeposition, enhances the battery's high-rate cycle characteristics, and maintains stable inter-electrode distance, reducing the risk of micro short-circuits and improving safety and performance during repeated charging and discharging.
Implementation Method 1
a restraining member that restrains the arrayed unit cells and spacers, in such a manner that an inherent stress is present in a direction in which the unit cells and the spacers are compressed along the array direction
Implementation Method 2
each spacer having a flat portion disposed so as to oppose the side surfaces, and a rib portion protruding from the flat portion towards the side surfaces
Data Source
AI summary
The present disclosure provides an assembled battery having a plurality of unit cells, spacers disposed so as to sandwich the unit cells, and restraining members that restrain the unit cells and the spacers in an array direction X. In each unit cell, a flat wound electrode body having a winding end fixed by a fixing member is accommodated in a battery case. The spacers are provided with rib portions protruding towards long side surfaces of the battery case. Flat portions of the electrode body each have a pressing region including a pressing site that opposes the rib portions, and a moderation region other than the pressing region. The pressing region includes at least the center of each flat portion in a winding axis direction, and a first pressing region over a direction along a major axis. The fixing member is disposed at the moderation region.