Lithium Secondary Battery Cathode Composition for Ignition Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face safety issues due to the generation of oxygen at the positive electrode, leading to potential ignition, especially under high-temperature conditions, and all-solid-state batteries do not match the performance of liquid electrolyte-based batteries in terms of output, capacity, and lifetime.
Innovation Solution
A lithium secondary battery design incorporating a positive electrode with an inorganic solid electrolyte and a non-aqueous electrolyte, where the inorganic solid electrolyte is uniformly distributed within the positive electrode mixture layer, covering 50% to 90% of the positive electrode active material surface, and a Si-based active material is used in the negative electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyolefin-based separators are used to ensure electrical insulation, then insulation between positive and negative electrodes is improved, but under high-temperature environment the separator shrinks and fails to provide insulation causing short circuit
Solution Approach 1:
The separator material is changed from polyolefin to aramid, which fundamentally alters the thermal properties. Aramid fibers maintain structural integrity at high temperatures (up to 500°C) whereas polyolefin melts and shrinks at temperatures above 100°C, thus resolving the contradiction between insulation reliability and high-temperature stability
Solution Approach 2:
The separator is constructed as a composite structure with aramid base layer providing high-temperature mechanical strength and heat-resistant coating layers (containing inorganic particles like alumina or silica) that further enhance thermal stability and prevent shrinkage, creating a multi-functional composite material that simultaneously provides insulation and high-temperature resistance
2Reliability
If all-solid-state batteries are applied to improve safety, then ignition risk is reduced, but output, capacity, and lifetime performance deteriorate compared to liquid electrolyte batteries
Solution Approach 1:
The invention merges the advantages of both solid and liquid electrolyte systems by using a gel polymer electrolyte that combines the flame-retardant safety of solid electrolytes with the high ionic conductivity and electrochemical stability of liquid electrolytes, thus achieving both safety improvement and performance maintenance
Solution Approach 2:
The electrolyte is designed as a composite gel polymer system incorporating flame-retardant additives, inorganic fillers (such as Li2SiO3 or Al2O3 particles), and optimized polymer matrices that provide both the safety characteristics of solid electrolytes and the performance characteristics of liquid electrolytes, resolving the contradiction between safety and productivity
3Reliability
If inorganic solid electrolyte is added to positive electrode to prevent ignition, then safety is improved, but device complexity increases
Solution Approach 1:
The flame-retardant inorganic solid electrolyte particles are selectively incorporated into the positive electrode coating layer where oxygen evolution occurs during charging, rather than throughout the entire battery structure. This localized approach provides ignition prevention exactly where needed while minimizing additional complexity and maintaining manufacturing simplicity
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 design significantly reduces the risk of ignition and enhances safety by preventing short circuits and oxygen generation, maintaining high performance comparable to liquid electrolyte-based batteries.
Implementation Method 1
the inorganic solid electrolyte is uniformly distributed within the positive electrode mixture layer, covering 50% to 90% of the positive electrode active material surface
Implementation Method 2
a lithium non-aqueous electrolyte containing a lithium salt and a non-aqueous organic solvent
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
According to an embodiment of the present disclosure, there is provided a lithium secondary battery comprising: a positive electrode in which a positive electrode mixture layer containing a positive electrode active material and an inorganic solid electrolyte is formed on one side or both sides of a positive electrode current collector, a negative electrode in which a negative electrode mixture layer containing an Si-based active material as a negative electrode active material is formed on one side or both sides of a negative electrode current collector, a separator interposed between the positive electrode and the negative electrode, and a lithium non-aqueous electrolyte containing a lithium salt and a non-aqueous organic solvent, wherein the inorganic solid electrolyte is included in an amount of 1.5 wt.% to 5 wt.% based on the total weight of the positive electrode mixture layer, and is uniformly distributed within the positive electrode mixture layer.