Molten Salt Battery Electrode Stacking Design
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Solution Overview
Problem
Molten-salt batteries face limitations in increasing electrode thickness and capacity due to low cation diffusion into particulate positive-electrode active materials, and existing techniques for size increase or space-saving designs are inefficient or impractical.
Innovation Solution
A molten-salt battery design with thinned positive and negative electrodes stacked alternately, connected in parallel, and housed in bag-like separators within a battery container, where the electrodes are pressed to maintain alignment and stability during charging and discharging, allowing for increased surface area and capacity without reducing voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the positive electrode is increased to achieve higher capacity, then the battery capacity increases, but the cation diffusion into the particulate positive-electrode active material becomes insufficient, limiting further thickness increase
Solution Approach 1:
The positive electrode is segmented into multiple thin electrodes stacked alternately with negative electrodes. This segmentation allows each thin positive electrode to maintain adequate cation diffusion while collectively achieving high battery capacity through the stacking of multiple electrodes connected in parallel.
2Quantity of substance
If sodium-sulfur battery techniques for increasing cell size are applied, then the battery capacity increases, but the battery volume increases proportionally, reducing space efficiency
Solution Approach 1:
The invention transitions from a conventional single-layer electrode configuration to a multi-layer stacked configuration in the vertical dimension. Multiple thin positive and negative electrodes are stacked alternately, allowing high capacity to be achieved by utilizing the vertical stacking dimension rather than simply increasing the horizontal footprint, thereby improving space efficiency.
3Area of moving object
If rolled electrode forms are used to increase electrode area, then the current collection area increases, but the housing efficiency in a rectangular parallelepiped battery container decreases
Solution Approach 1:
Instead of using rolled electrodes that occupy excessive horizontal space, the invention stacks multiple thin planar electrodes in the vertical dimension. This approach achieves large total electrode area while maintaining compact rectangular parallelepiped battery container dimensions, thereby improving housing efficiency.
4Quantity of substance
If the number of stacked electrodes is increased to achieve higher capacity, then the battery capacity increases, but the alignment and stability of electrodes during charging and discharging becomes difficult to maintain
Solution Approach 1:
Multiple thin positive electrodes are connected in parallel and stacked alternately with negative electrodes, forming an integrated stable structure. This merging of multiple electrodes into a unified stacked assembly maintains alignment stability during charging and discharging while achieving high battery capacity.
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 achieves high-capacity and high-energy-density performance with stable charging/discharging processes, maintaining capacity density across varying thicknesses and hour rates, while preventing short circuits and misalignment.
Implementation Method 1
a separator containing a molten salt composed of an alkali metal cation, such as sodium or potassium, and an anion containing fluorine
Implementation Method 2
the cation is less likely to diffuse deeply into the positive-electrode active material
Data Source
AI summary
A molten-salt battery is provided with rectangular plate-like negative electrodes (21) and rectangular plate-like positive electrodes (41) each housed in a bag-shaped separator (31). The negative electrodes (21) and positive electrodes (41) are arranged laterally and alternately in a standing manner. A lower end of a rectangular tab (22) for collecting current is joined to an upper end of each negative electrode (21) close to a side wall (1A) of a container body (1). The upper ends of the tabs (22) are joined to the lower surface of a rectangular plate-like tab lead (23). A lower end of a rectangular tab (42) for collecting current is joined to an upper end of each positive electrode (41) close to a side wall (1B) of the container body (1). The upper ends of the tabs (42) are joined to the lower surface of a rectangular plate-like tab lead (43).