Stacked Battery Heat Management via Bipolar Segmentation
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Solution Overview
Problem
High-energy electrical storage devices face issues with heat generation and unstable reactions due to increased capacity and capacitance, which can lead to internal short circuits and deteriorated cycle characteristics when electrode areas are enlarged.
Innovation Solution
A stacked battery design with a bipolar structure, featuring a specific ratio of length to electrode area, where electric elements are connected in series via bipolar current collector layers, and optionally including fuse or PTC layers, to manage heat and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If battery capacity and capacitance are increased to secure high energy level, then energy storage capability is improved, but heat generation occurs at short-circuiting portions leading to safety issues
Solution Approach 1:
The battery is divided into multiple electric elements connected in series, with each element having controlled capacity. This segmentation distributes the total energy storage across multiple units while limiting heat generation in any single element during short-circuit conditions.
Solution Approach 2:
The patent specifies precise parameter ranges: capacity ≤ 0.32 Ah per element, capacitance ≤ 0.01 Ah/V per element, and h/S ratio > 1. These parameter changes optimize the balance between energy storage and heat generation suppression.
2Use of energy by moving object
If electrode area is enlarged to secure high energy level, then energy storage capability is improved, but unstable reaction occurs leading to deteriorated cycle characteristics
Solution Approach 1:
Instead of using a single large electrode area, the patent divides the battery into multiple elements with smaller electrode areas (S ≤ 10 cm² per element). This segmentation maintains high total energy storage while ensuring stable reactions in each element, improving cycle characteristics.
Solution Approach 2:
The patent establishes specific parameter ranges: electrode area S between 1 cm² and 10 cm², and h/S ratio greater than 1. These parameter changes ensure stable electrochemical reactions while achieving high energy storage through series connection of multiple elements.
3Use of energy by moving object
If multiple electric elements are connected in series to increase voltage and energy, then energy level is improved, but heat concentration occurs at short-circuit portions
Solution Approach 1:
The patent specifies capacity ≤ 0.32 Ah per element in series connections. This parameter control ensures that while total voltage and energy increase through series connection, the heat generation at any short-circuit point remains limited due to the small capacity of individual elements.
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 heat generation and unstable reactions while maintaining a high energy level by controlling the length to electrode area ratio and using bipolar current collectors to connect electric elements in series.
Implementation Method 1
a Positive Temperature Coefficient (PTC) layer is provided between a current collector layer and an active material layer, and the resistance of the PTC layer is increased when heat is generated in a battery
Implementation Method 2
when internal short circuits occur in a battery, increasing a battery capacity and a capacitance leads to concentration of electric power that is stored in the battery at a short-circuiting portion to easily generate heat
Data Source
AI summary
To suppress heat generation in a stacked battery including a plurality of electric elements in internal short circuits and an unstable reaction when the battery is operated while an energy level is increased, the stacked battery includes a stack comprising a first current collector layer, a second current collector layer, a plurality of bipolar current collector layers that are arranged between the first and second current collector layers at intervals in the stacking direction, a plurality of electric elements, an anode active material layer, and an electrolyte layer that is arranged between the cathode and anode active material layers, where the ratio h/S (cm−1) of a length h (cm) between the one end face and the other end face in the stacking direction of the stack to an electrode area S (cm2) on a cross section orthogonal to the stacking direction of the stack is more than 1.