Elastic Spacer Battery Module for Swelling and Electrolyte Control
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Solution Overview
Problem
Existing battery modules face challenges in maintaining the capacity of secondary batteries during repeated charging and discharging, and in preventing electrolyte discharge from the battery case, due to uncontrolled expansion of the batteries.
Innovation Solution
A battery module design featuring a pair of secondary batteries with rectangular electrodes and a rectangular parallelepiped case, along with an elastic spacer between them. The aspect ratio of the electrodes is limited to 10 or less, and the spring constant of the spacer is set between 0.03 MPa/mm and 5.4 MPa/mm to control the swelling rate of the battery case within 0.1% to 10%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery module is restrained from both sides in an arrangement direction of each secondary battery so that the expansion of each secondary battery is limited, then the capacity decrease due to electrode separation is suppressed, but the electrolyte may be discharged from a case of the secondary battery
Solution Approach 1:
The patent changes the physical parameters of the spacer by controlling its foam density to be 20 kg/m³ or more, which adjusts its elastic modulus and compression characteristics. This parameter optimization allows the spacer to provide appropriate restraint force that prevents electrode separation while avoiding excessive compression that would cause electrolyte discharge
Solution Approach 2:
The patent employs a foam-based spacer that can dynamically adapt its compression level according to the swelling pressure of the secondary batteries during charging cycles. The spacer compresses when batteries expand and rebounds when they contract, providing dynamic restraint that maintains electrode contact without causing electrolyte discharge
2Device complexity
If the expansion of each secondary battery is not limited at all, then the battery structure is simpler, but a distance between electrodes may increase due to repeated charging and discharging, and thus a capacity of the secondary battery may decrease
Solution Approach 1:
The patent introduces a foam spacer as an intermediary component between adjacent secondary batteries. This spacer acts as a mediator that provides gentle, distributed restraint force to maintain electrode contact during charging cycles, achieving capacity retention without requiring complex rigid restraint structures
Solution Approach 2:
The patent uses a foam-based flexible spacer that can deform elastically to accommodate battery swelling while maintaining continuous contact pressure on the battery cases. This flexible restraint mechanism preserves electrode contact and prevents capacity fade without imposing rigid structural constraints
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 design effectively suppresses the decrease in capacity of secondary batteries due to repeated charging and discharging, while also preventing electrolyte discharge from the battery case, thereby maintaining battery performance and safety.
Implementation Method 1
The spacer is made of an elastic body. A spring constant of the spacer is 0.03 MPa/mm or more and 5.4 MPa/mm or less.
Implementation Method 2
a surface pressure of the spacer when the secondary batteries are compressed until a thickness of the spacer becomes D−0.001d is α1, a surface pressure of the spacer when the secondary batteries are compressed until the thickness of the spacer becomes D−0.002d is α2
Data Source
AI summary
A battery module includes a pair of secondary batteries disposed adjacent to each other and a spacer disposed between the secondary batteries. Each of the secondary batteries includes a plurality of electrodes each of which has a rectangular shape and is disposed to face each other, a case configured to house the electrodes, the case having a rectangular parallelepiped shape, and an electrolyte in the case. The spacer is made of an elastic body. An aspect ratio of each of the electrodes is 10 or less, and a spring constant of the spacer is 0.03 MPa/mm or more and 5.4 MPa/mm or less.