Magnetic Separator and Ceramic Layer for Battery Dendrite Blocking
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Solution Overview
Problem
Lithium secondary batteries face issues with dendrite growth leading to separator penetration, causing electrical short-circuits and explosions, and volume changes resulting in separation between the anode active material and the negative electrode current collector, which reduces charge/discharge capacity and shortens lifespan.
Innovation Solution
A secondary battery design incorporating a magnetic separator with an accommodating layer of ceramic powder, which moves based on magnetism to prevent dendrite contact with the separator and includes a gel state to enhance fluidity and pore structure for ion mobility, and a water-soluble resin coating to retain the magnetic material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used without magnetic properties, then the device complexity is low, but dendrites can penetrate the separator causing safety issues
Solution Approach 1:
The separator is constructed as a composite material incorporating magnetic particles (such as iron oxide or magnetite) into the separator matrix. This composite structure provides both the mechanical separation function and the magnetic responsiveness needed to prevent dendrite penetration while maintaining relatively simple device architecture
Solution Approach 2:
The magnetic separator acts as an intermediary between the anode mixture and the traditional separator. The accommodating layer containing ceramic powder with magnetic material is positioned between the anode and separator, using magnetic field interaction to dynamically block dendrite growth paths without requiring complex active control systems
2Quantity of substance
If the anode active material volume changes during charge and discharge, then the charge/discharge capacity is improved, but separation between the anode active material and negative electrode current collector occurs
Solution Approach 1:
The binder composition parameters are changed by incorporating specific ratios of carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR). This modified binder composition provides enhanced adhesion properties that can accommodate the volume changes of the anode active material during lithium insertion and extraction cycles, preventing separation while maintaining electrical contact
Solution Approach 2:
A composite binder system combining CMC and SBR is used instead of a single binder material. The CMC provides structural integrity and adhesion, while SBR contributes flexibility and elasticity, creating a composite binder that can dynamically respond to volume changes in the anode active material without losing adhesion to the current collector
3Reliability
If ceramic powder is added to the accommodating layer, then dendrite contact with separator is prevented, but the device complexity increases
Solution Approach 1:
The ceramic powder particles in the accommodating layer possess inherent magnetic properties that enable them to automatically align and position themselves in response to the magnetic field from the separator. This self-organizing behavior provides dendrite blocking functionality without requiring external actuators or complex control mechanisms
Solution Approach 2:
The accommodating layer is designed with localized properties: ceramic powder with magnetic material is concentrated in the region between the anode mixture and separator where dendrite formation is most likely. The layer has specific porosity and thickness characteristics optimized for dendrite blocking while maintaining ion transport, providing targeted protection without complicating the overall battery structure
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
Prevents separator penetration by dendrites, suppressing separation between the anode active material and the negative electrode current collector, thereby enhancing safety and extending the battery's charge/discharge capacity and lifespan.
Implementation Method 1
a separator interposed between the positive electrode current collector and the negative electrode current collector, and having magnetism; and an accommodating layer provided between the negative electrode current collector and the separator, and accommodating ceramic powder including a magnetic material to move toward one side of the separator based on the magnetism of the separator
Data Source
AI summary
Disclosure is a secondary battery including: a positive electrode current collector to which a cathode mixture containing a cathode active material is applied; a negative electrode current collector to which an anode mixture containing an anode active material is applied; a separator interposed between the positive electrode current collector and the negative electrode current collector, and having magnetism; and an accommodating layer provided between the negative electrode current collector and the separator, and accommodating ceramic powder including a magnetic material to move toward one side of the separator based on the magnetism of the separator. Thus, the ceramic powder having the magnetic material is arranged along the longitudinal direction of the separator as the accommodating layer moves close to the separator based on increase in the volume of the anode active material, thereby preventing dendrites from coming into contact with the separator. Therefore, the separator is prevented from being penetrated by the dendrites.