Ceramic Binder Separator for Lithium Battery Thermal Stability
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Solution Overview
Problem
Conventional lithium rechargeable battery separators lack sufficient heat resistance and safety features, particularly during internal short circuits and overcharge conditions, leading to potential ignition and explosion due to deformation and lithium dendrite formation.
Innovation Solution
A lithium rechargeable battery with a separator made of a porous ceramic material and a binder with a crystal melting temperature of 250°C or higher, or a non-crystalline resin with an initial decomposition temperature of 250°C or higher, providing enhanced thermal and electrical properties and improved safety characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional polyolefin-based porous membrane separator is used, then the separator can provide basic separation function and shutdown action, but it shows poor heat resistance and deforms under high temperature conditions leading to safety issues
Solution Approach 1:
The patent applies composite materials by combining inorganic ceramic particles (alumina, silica, zirconia, or magnesia) with an organic binder to create a porous membrane separator. This composite structure provides both the separation function of the porous membrane and the high temperature stability of ceramic particles, resolving the contradiction between basic separator functionality and heat resistance. The ceramic particles maintain structural integrity at high temperatures while the binder provides adhesion and flexibility.
Solution Approach 2:
The patent changes the thermal parameters of the separator by incorporating ceramic particles with high melting points and controlling the binder's glass transition temperature to be below 150°C. This parameter modification allows the separator to maintain dimensional stability and porosity at elevated temperatures (200-300°C) where conventional polyolefin separators would deform and shrink, thereby improving heat resistance while maintaining reliability.
2Area of stationary object
If a sheet-like porous membrane separator is used, then the separator can separate cathode and anode, but it shrinks under internal heat emission causing area reduction and potential short circuit
Solution Approach 1:
The patent uses composite materials consisting of ceramic particles dispersed in a binder matrix to create a separator that resists thermal shrinkage. The ceramic particles (alumina, silica, zirconia, or magnesia) have high thermal stability and do not shrink at battery operating temperatures, providing a rigid skeletal structure that maintains the separator's area even when the binder softens, thus preventing short circuits under heat emission conditions.
Solution Approach 2:
The patent exploits differential thermal expansion properties by combining materials with different thermal behaviors. The ceramic particles have low thermal expansion coefficients and maintain dimensional stability at high temperatures, while the binder provides flexibility. This combination ensures that the overall separator structure maintains its area and porosity under heat emission, preventing the shrinkage that would otherwise cause cathode-anode contact.
3Reliability
If a porous membrane with softened resin is used for shutdown action, then lithium ion movement is blocked during short circuit, but the resin deforms and loses effectiveness under severe heat conditions
Solution Approach 1:
The patent employs composite materials where ceramic particles provide structural stability and dimensional integrity while the binder matrix provides the shutdown mechanism. The ceramic particles (alumina, silica, zirconia, or magnesia) maintain their rigid structure at high temperatures, preventing deformation, while the binder can still undergo the shutdown action by blocking pores at elevated temperatures. This composite approach ensures both short circuit resistance through shutdown and structural stability under severe heat conditions.
Solution Approach 2:
The patent modifies the thermal parameters of the separator system by controlling the binder's glass transition temperature (below 150°C) and incorporating ceramic particles with high melting points. This parameter optimization allows the binder to perform shutdown action at moderate elevated temperatures while the ceramic particles maintain structural stability even at severe heat conditions (200-300°C), ensuring both short circuit resistance and structural integrity.
4Object-affected harmful factors
If a film-like separator is used, then the separator can prevent short circuit under normal conditions, but it cannot prevent lithium dendrite formation and penetration under overcharge conditions
Solution Approach 1:
The patent applies composite materials with ceramic particles (alumina, silica, zirconia, or magnesia) that create a more robust separator structure. The ceramic particle network provides mechanical strength and tortuous pathways that resist lithium dendrite penetration, while maintaining the porosity needed for ion transport. This composite structure enhances resistance to lithium dendrites under overcharge conditions while preserving short circuit prevention capability under normal operating conditions.
Solution Approach 2:
The patent utilizes porous materials with optimized pore structures formed by the ceramic particle-binder composite. The porous structure provides tortuous pathways for lithium ion transport that hinder the linear growth of lithium dendrites, while still allowing sufficient ion conductivity for normal battery operation. The pore size and distribution are controlled to balance dendrite resistance with ion transport efficiency, maintaining short circuit prevention under both normal and overcharge conditions.
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 battery exhibits excellent short circuit resistance and heat resistance, maintaining thickness stability under high-temperature conditions and preventing direct contact between the cathode and anode, thus enhancing safety and preventing explosions.
Implementation Method 1
the binder includes at least one crystalline resin having a crystal melting temperature of 250° C. or higher or at least one non-crystalline resin having an initial decomposition temperature of 250° C. or higher
Implementation Method 2
the separator includes a porous membrane formed of a ceramic material and a binder... providing enhanced thermal and electrical properties
Implementation Method 3
the separator includes a porous membrane formed of a ceramic material and a binder
Implementation Method 4
it is important for the separator to allow the infiltration of an electrolyte necessary for carrying out electrochemical reactions in the battery and to maintain high ion conductivity
Implementation Method 5
The separator in a lithium rechargeable battery has the basic function of separating the cathode and the anode from each other so as to prevent a short circuit
Data Source
AI summary
A lithium rechargeable battery includes a separator that shows excellent safety characteristics such as short circuit resistance and heat resistance. The lithium rechargeable battery includes a cathode, an anode, a separator that separates the cathode and the anode from each other, and a non-aqueous electrolyte, wherein the separator includes a porous membrane formed of a ceramic material and a binder, and wherein the binder includes at least one crystalline resin having a crystal melting temperature of 250° C. or higher or at least one non-crystalline resin having an initial decomposition temperature of 250° C. or higher.