Columnar Secondary Battery Electrode Structure for Ion Conduction
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving higher energy densities and safety due to limitations in existing electrode structures, where increasing energy density compromises ion conductivity and safety mechanisms.
Innovation Solution
A secondary battery design featuring columnar electrodes bound together with a separation membrane and current collecting units, which serves as a fuse mechanism to enhance safety and energy density by reducing ion conduction distance and eliminating the need for internal current collectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of active material layers is increased to increase battery capacity, then the energy density is improved, but the ion concentration gradient in the thickness direction becomes difficult to moderate and ion conductivity deteriorates
Solution Approach 1:
The patent divides the electrode structure into multiple thin-layered columns stacked in the thickness direction, with each column containing multiple active material layers separated by current collectors. This segmentation reduces the ion conduction path length within each layer while maintaining high overall capacity through the stacked configuration, thereby resolving the contradiction between capacity and ion conductivity.
2Reliability
If safety mechanisms such as current fuses or temperature fuses are added, then safety is improved, but the device complexity and space occupation increase
Solution Approach 1:
The current collectors in the patent serve multiple functions: they collect current from active material layers, provide structural support for stacking, act as separators between layers, and function as temperature fuses that melt to disconnect circuits under overheating conditions. This multi-functionality integrates safety mechanisms into the existing structure without adding separate components, thereby improving safety while minimizing complexity.
3Reliability
If current collectors are embedded in electrodes to collect current, then electrical conduction is improved, but the ion conduction distance increases and energy density decreases
Solution Approach 1:
The patent segments the electrode into multiple thin active material layers separated by current collectors, creating a stacked columnar structure. This segmentation ensures that no ion conduction path exceeds a predetermined length within each layer, maintaining high ion conductivity while the stacked configuration maximizes the amount of active material per unit volume, thereby preserving energy density.
Solution Approach 2:
The patent transitions from a planar electrode structure to a three-dimensional stacked columnar structure. By stacking multiple thin layers in the thickness direction, the design achieves efficient current collection through the current collectors while minimizing ion conduction distances within each layer, thus resolving the trade-off between electrical conduction and energy density.
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 increases energy density and safety by shortening ion conduction paths and utilizing the connecting units as a fuse mechanism to prevent overheating during short-circuiting, while maintaining high conductivity and capacity.
Implementation Method 1
a separation membrane that has ion conductivity and insulates between the first electrode and the second electrode
Implementation Method 2
a structure in which a first connecting unit that is connected to the first electrode and melts when short-circuiting occurs is connected to the first current collecting unit
Data Source
AI summary
A secondary battery includes a first electrode which is a columnar body having a first active material; a first current collecting unit connected to the first electrode; a second electrode having a second active material; a second current collecting unit connected to the second electrode; and a separation membrane that has ion conductivity and insulates between the first electrode and the second electrode. The secondary battery has a structure in which a plurality of the first electrodes are bound together while being adjacent to the second electrode with the separation membrane therebetween. A first connecting unit that is connected to the first electrode and melts when short-circuiting occurs may be connected to the first current collecting unit.