Phosphazene Anode Coating for Battery Flammability Reduction
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Solution Overview
Problem
Lithium-ion batteries face challenges in maintaining safety and performance across a wide temperature range due to the flammability of conventional electrolytes, which affects their thermal stability and cycle life.
Innovation Solution
Incorporating fire-retardant additives and carbon nanotubes into the electrolyte and electrode formulations, along with a vent design for pressure release, to enhance thermal stability and conductivity, thereby reducing flammability and improving safety and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in lithium-ion batteries, then good performance and wide temperature operation are achieved, but flammability increases and safety deteriorates
Solution Approach 1:
A coating layer comprising phosphazene and at least one of graphite or carbon is applied to the anode, serving as an intermediary barrier between the flammable electrolyte and the anode. This coating reduces the flammability of the electrolyte system while maintaining battery performance and wide temperature operation capabilities
Solution Approach 2:
The anode is modified with a composite coating structure combining phosphazene (a fire-retardant material) with graphite or carbon materials. This composite coating provides both safety benefits by reducing electrolyte flammability and maintains electrical conductivity for good battery performance
2Object-affected harmful factors
If fire-reducing components are added to the electrolyte, then flammability is reduced, but battery performance including rate capability, capacity and cycle life deteriorates
Solution Approach 1:
Instead of adding fire-reducing components to the electrolyte that harm performance, the invention extracts the fire-protection function to a separate coating layer applied to the anode. This separates the safety function from the electrolyte, allowing the electrolyte to maintain its performance characteristics while the coating provides flammability reduction
Solution Approach 2:
The phosphazene-containing coating acts as an intermediary layer that provides fire protection without interfering with the electrolyte's ionic conductivity and electrochemical performance, thus maintaining rate capability, capacity and cycle life
3Reliability
If fire-retardant additives are added to improve thermal stability, then safety is improved, but electrolyte operational temperature range and performance are compromised
Solution Approach 1:
The phosphazene coating serves as a thermal stability enhancer that does not interfere with the electrolyte's temperature-dependent ionic conductivity, allowing the battery to maintain both improved thermal stability and wide operational temperature range
Solution Approach 2:
Fire-retardant properties are localized to the anode coating layer where they are most needed for safety, while the bulk electrolyte maintains its temperature-dependent performance characteristics, enabling wide operational temperature range
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 achieves reduced flammability, improved thermal stability, and extended cycle life of lithium-ion batteries across a wide temperature range, preventing thermal runaway and enhancing safety during abnormal operations.
Implementation Method 1
an electrolyte comprising a fire-retardant additive
Implementation Method 2
inclusion of a Carbon Nanotube (CNT) material in the electrode formulation to promote the thermal conductivity of the electrodes
Implementation Method 3
configuration of a cell with a vent design allowing the safe release of pressure that may build up during abnormal operations
Implementation Method 4
In a charge operation of the battery, the Li+ ion migrates to the graphite anode and lithiates the C and forms LiCx
Data Source
AI summary
An improved electrolyte including a fire-retardant additive suitable for application in wide temperature cell and/or battery operation with safer cell design, a battery including the electrolyte and a separator optionally containing a fire-retardant additive, improved electrical and thermal conductive electrodes are disclosed. The presence of the fire-retardant additive reduces flammability of the electrolyte and improved the overall safety of the battery.