Positive Electrode Safety Layer for Faster Overcharge Shutdown
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion batteries face safety issues such as fire and explosion due to overcharge, which deteriorate electrical performance and pose safety hazards, and existing solutions using PTC materials either fail to improve safety or adversely affect electrochemical performance.
Innovation Solution
A positive electrode plate with a safety layer comprising a binding substance, a conductive substance, and a special sensitive substance with monosaccharide structural units and carbonate or phosphate groups, which degrades chemically at excessive voltage and temperature to block electronic conduction, preventing thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PTC material layer is used for safety improvement, then overcharge protection is enhanced, but response speed is insufficient due to slow thermal response
Solution Approach 1:
The patent optimizes parameters including PTC material particle size, layer thickness, and composition ratios to enhance thermal response speed. By controlling these parameters, the safety layer achieves faster thermal diffusion and quicker PTC effect activation, thus improving response speed while maintaining overcharge protection.
2Reliability
If PTC material is added to improve safety, then thermal runaway prevention is enhanced, but manufacturing complexity increases due to additional processing steps
Solution Approach 1:
The patent combines the safety layer formation with the existing electrode manufacturing process by applying the safety layer during the same coating and drying steps used for active material layers. This merging of processes adds minimal complexity while achieving thermal runaway prevention.
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 solution effectively prevents safety hazards like fire and explosion while improving overcharge safety and electrical performance by providing a faster and more reliable response compared to traditional PTC materials.
Implementation Method 1
each molecule of the special sensitive substance includes monosaccharide structural units, and carbonate groups and/or phosphate groups; and at least part of the carbonate groups and/or phosphate groups are bonded to two or more of the monosaccharide structural units
Implementation Method 2
the carbonate groups and/or phosphate groups are bonded to two or more of the monosaccharide structural units
Implementation Method 3
PTC materials, also referred to as positive temperature coefficient thermal materials, are characterized in having electric resistivity that increases with temperature. When the temperature exceeds a particular threshold, electric resistivity of a PTC material steps up rapidly
Data Source
AI summary
This application provides a positive electrode plate and an electrochemical apparatus and device associated therewith. The positive electrode plate includes a positive electrode current collector, a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, and a safety layer disposed between the positive electrode active material layer and the positive electrode current collector. The safety layer includes a binding substance, a conductive substance, and a special sensitive substance, where the special sensitive substance is at least one product of esterification of polysaccharide in which a degree of esterification of monosaccharide units is 35% to 98%. The electrochemical apparatus prepared by using the positive electrode plate of this application has significantly improved safety and electrical performance (such as cycling performance).