Thick SEI Layer and Boron Nitride Nanosheets for High-Temp Battery Stability
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Solution Overview
Problem
Lithium-ion battery (LIB) performance is compromised at high ambient temperatures due to increased self-discharge rates, which current thin SEI layers cannot effectively manage, leading to reduced lifespan and energy density, and the use of battery thermal management systems introduces additional load that lowers power density.
Innovation Solution
Forming LIB cells with thicker SEI layers determined by specific thickness values to limit self-discharge at high temperatures, and utilizing boron nitride nanosheets for enhanced thermal communication and passive heat transfer to reduce the load on thermal management systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If thin SEI layers are used to maximize LIB cell lifespans, then battery lifespan is improved, but self-discharge control at high temperatures deteriorates
Solution Approach 1:
The patent changes the thickness parameter of the SEI layer from conventional thin (few nanometers) to thicker (optimized range), which fundamentally alters the layer's protective capabilities. This parameter change enables the SEI layer to effectively block self-discharge pathways at high temperatures while maintaining long-term stability, resolving the contradiction between lifespan and high-temperature reliability
Solution Approach 2:
The patent applies preliminary protective action by forming a pre-engineered SEI layer with specific thickness and composition before the battery enters service. This pre-formed layer is designed to withstand high-temperature conditions and prevent self-discharge from the outset, rather than relying on the battery's natural aging process
2Temperature
If battery thermal management systems are used to control operating temperature, then temperature control is improved, but power density deteriorates due to additional load
Solution Approach 1:
The patent enables the battery to self-manage thermal effects through its engineered SEI layer, which provides intrinsic thermal stability and reduced self-discharge at elevated temperatures. This self-service capability reduces or eliminates the need for active thermal management systems, thereby avoiding the power density penalty associated with cooling loads
Solution Approach 2:
The patent extracts the thermal management function from the overall battery system by incorporating thermal resilience directly into the SEI layer structure. This extraction eliminates the separate thermal management subsystem and its associated power consumption, resolving the contradiction between temperature control and power density
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 approach significantly reduces self-discharge to 10% or less over four weeks at 60°C, maintaining power density and extending the driving range of electric vehicles by minimizing the energy consumed by thermal management systems.
Implementation Method 1
utilizing boron nitride nanosheets for enhanced thermal communication and passive heat transfer
Implementation Method 2
The resulting SEI layer limits further reduction of electrolyte, and thus, electrochemically stabilizes the LIB cell
Data Source
AI summary
In general, the present disclosure is directed to forming lithium ion battery (LIB) cells with structure and chemistry that achieves formation of a solid electrolyte interphase (SEI) layer that allows for operating in relatively high ambient temperature environments, e.g., up to and exceeding 60° C., while significantly reducing self-discharge amounts, e.g., relative to other LIB cells formed with SEI layers measuring about 1-2 nanometers in thickness. For example, one non-limiting embodiment of the present disclosure enables a self-discharge amount for a LIB cell of 10% or less over a four (4) week period of time when operating at an ambient temperature of 60 degrees Celsius.