3D Battery Electrode Constraint Structure for Swelling Control
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Solution Overview
Problem
The persistent challenge in rocking chair battery cells is the expansion and contraction of electrodes during repeated charging and discharging cycles, leading to reliability and cycle life issues due to electrical shorts and battery failures.
Innovation Solution
The implementation of constraint structures, including a primary and secondary growth constraint system, to mitigate the macroscopic expansion of electrodes, thereby improving energy density, reliability, and cycle life of batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrodes are allowed to expand and contract freely during battery cycling, then the battery can maintain its electrochemical function, but the electrodes will experience macroscopic expansion leading to electrical shorts and battery failures
Solution Approach 1:
The patent employs flexible constraint structures including thin film coatings and flexible barriers that can accommodate the expansion and contraction of electrodes during cycling while preventing macroscopic swelling. These flexible elements conform to the electrode surface and restrict volume growth without causing mechanical failure, thereby maintaining battery reliability while allowing necessary electrochemical volume changes.
Solution Approach 2:
The patent utilizes porous constraint structures such as porous coatings and porous barriers that allow ion transport while physically restricting electrode expansion. The porous architecture provides mechanical constraint against macroscopic swelling but maintains sufficient porosity to permit electrolyte penetration and ionic conduction, thus preventing electrical shorts while preserving electrochemical function.
2Reliability
If constraint structures are implemented to restrict electrode expansion, then battery reliability and cycle life improve, but the device complexity increases
Solution Approach 1:
The patent integrates constraint structures that serve multiple functions simultaneously: they act as mechanical barriers to prevent electrode swelling, provide structural support to the electrode assembly, and in some cases serve as additional active material layers or protective coatings. This multi-functionality reduces the need for separate constraint components, thereby limiting the increase in device complexity while maintaining improved reliability and cycle life.
3Manufacturing precision
If the electrode assembly dimensions are constrained, then the increase in Feret diameter during cycling is limited, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies constraint structures during the electrode assembly manufacturing process before the electrodes undergo cycling. The constraints are pre-installed on electrode surfaces or within the assembly structure, establishing dimensional boundaries in advance. This preliminary application of constraints allows for controlled electrode formation and initial cycling without excessive expansion, thereby limiting Feret diameter increase while managing manufacturing precision requirements through pre-established geometric boundaries.
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 use of constraint structures effectively limits the increase in Feret diameter of the electrode assembly during cycling, enhancing the reliability and extending the cycle life of secondary batteries.
Implementation Method 1
The set of electrode constraints restrains growth of the electrode assembly in the longitudinal direction such that any increase in the Feret diameter of the electrode assembly in the longitudinal direction over 20 consecutive cycles of the secondary battery is less than 20%
Data Source
AI summary
A secondary battery is provided for cycling between a charged and a discharged state, the secondary battery including a battery enclosure, an electrode assembly, carrier ions, a non-aqueous liquid electrolyte within the battery enclosure, and a set of electrode constraints. The set of electrode constraints includes a primary constraint system having first and second primary growth constraints and at least one primary connecting member, the first and second primary growth constraints separated from each other in the longitudinal direction, wherein the primary constraint array restrains growth of the electrode assembly in the longitudinal direction such that any increase in the Feret diameter of the electrode assembly in the longitudinal direction over 20 consecutive cycles of the secondary battery is less than 20%. The set of electrode constraints further includes a secondary constraint system having first and second secondary growth constraints connected by at least one secondary connecting member, wherein the secondary constraint system at least partially restrains growth of the electrode assembly in a second direction upon cycling of the secondary battery.