3D Battery Constraint Structures for Electrode Growth Control
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Solution Overview
Problem
Rocking chair secondary batteries face reliability and cycle life issues due to electrode expansion and contraction during charging and discharging, leading to electrical shorts and battery failures.
Innovation Solution
Incorporating a set of electrode constraints, including primary and secondary growth constraint systems, to restrain the macroscopic expansion of electrodes, thereby controlling growth and maintaining electrode assembly dimensions within specific limits during cycling.
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 good electrochemical performance, but the electrodes will deform and cause electrical shorts leading to battery failure
Solution Approach 1:
The patent applies flexible constraint structures comprising constraint members that can elastically deform to accommodate electrode expansion and contraction during battery cycling. The constraint members are configured to apply restraining forces to the electrodes, preventing excessive deformation and electrical shorts while maintaining flexibility to allow normal volume changes. This resolves the contradiction by providing mechanical stability through flexible constraints rather than rigid fixation.
Solution Approach 2:
The patent implements counteracting forces through constraint members that apply restraining forces opposite to the expansion direction of electrodes during charging. These constraint members are positioned to exert compressive forces that balance the expansion pressure, preventing electrode deformation and electrical shorts while allowing controlled volume changes. This counterbalancing approach maintains both reliability and dimensional stability.
2Reliability
If constraint structures are added to prevent electrode expansion, then battery reliability and cycle life are improved, but the device complexity increases
Solution Approach 1:
The constraint members are designed to serve multiple functions: they constrain electrode expansion, provide mechanical support, and maintain electrode alignment. By integrating these multiple functions into single constraint components, the patent reduces the number of separate parts needed, thereby lowering device complexity while maintaining reliability improvements.
Solution Approach 2:
The patent combines the constraint function with the electrode structure itself by integrating constraint members directly onto or into the electrode assembly. This merging of functions eliminates separate constraint systems and reduces overall device complexity while still providing the necessary reliability improvements through controlled electrode dimensioning.
3Quantity of substance
If the ratio of electrode length and width to height is increased to at least 2:1, then energy density is improved, but the electrode becomes more prone to expansion issues
Solution Approach 1:
The constraint members are configured to specifically address the expansion risks associated with high aspect ratio electrodes. These flexible constraints adapt to the elongated geometry of the electrodes, providing targeted restraint in directions where expansion is most problematic while allowing the beneficial high energy density configuration to be maintained.
Solution Approach 2:
The patent applies constraint members at specific locations and orientations tailored to the high aspect ratio geometry of the electrodes. Rather than uniform constraints throughout, the system provides localized restraint where expansion is most likely to cause failure, allowing the rest of the electrode structure to maintain its optimal high energy density configuration.
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 constraint systems effectively limit electrode expansion, enhancing the energy density, reliability, and cycle life of secondary batteries by preventing deformation and electrical shorts.
Implementation Method 1
the electrode active material has the capacity to accept more than one mole of carrier ion per mole of electrode active material when the secondary battery is charged from a discharged state to a charged state
Implementation Method 2
an electrically insulating microporous separator material electrically separating members of the electrode and counter-electrode populations
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.