Imidazolidinylide compound for use as a shut-down additive for lithium ion batteries and electrolyte and battery
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Solution Overview
Problem
Existing lithium-ion battery electrolytes lack intrinsic chemical overcharge protection, leading to thermal runaway during overcharging, and known shut-down additives either have low chemical stability or negatively impact cell cycling, while compounds like NHC-PF5 and NHC-PF4CF3 pose toxicity risks.
Innovation Solution
Development of imidazolidinylide compounds with varying substituents as shut-down additives that enhance working voltage, prevent thermal runaway, and minimize toxicity by avoiding phosphate groups, allowing for higher energy efficiency and extended service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shut-down additives are added to provide overcharge protection, then thermal runaway is prevented, but cell cycling performance deteriorates
Solution Approach 1:
The patent modifies the molecular structure of shut-down additives by replacing phosphate groups with carboxylate groups and adjusting substituent parameters (R1-R6 groups) to optimize the balance between shut-down potential and cycling stability. Specific parameter changes in the chemical structure allow tuning of decomposition voltage while maintaining cell cycling performance.
Solution Approach 2:
The patent employs composite additive systems combining multiple imidazolidinylide compounds with different substituent patterns (combinations of fluorinated alkyl, aryl, and cycloalkyl groups) to achieve both effective shut-down protection and minimal impact on cell cycling. The composite approach allows synergistic effects where different molecules contribute different properties.
2Reliability
If phosphate-containing shut-down additives (NHC-PF5, NHC-PF4CF3) are used, then shut-down function is achieved, but toxicity increases
Solution Approach 1:
The patent extracts and removes the harmful phosphate group (PF5, PF4CF3) from the molecular structure of shut-down additives while retaining the essential imidazolidinylide core structure and shut-down functionality. This extraction eliminates the source of toxicity (PF5 gas generation) while preserving the protective function through alternative carboxylate-based decomposition products.
Solution Approach 2:
The patent converts the potentially harmful phosphate groups into beneficial carboxylate groups that provide similar shut-down functionality without generating toxic substances. The carboxylate substituents decompose into harmless or less harmful products, transforming a harmful chemical feature into a beneficial one.
3Object-generated harmful factors
If NHC-BF3 is used as shut-down additive, then toxicity is reduced, but working voltage is limited to lower voltages
Solution Approach 1:
The patent changes the electronic and steric parameters of the substituents (introducing electron-withdrawing fluorinated groups, aromatic groups, and cyclic groups) to increase the decomposition voltage of the shut-down additive from 4.5 V to higher values, enabling use at elevated working voltages while maintaining low toxicity.
Solution Approach 2:
The patent introduces different types of substituent groups (fluorinated alkyl, aryl, cycloalkyl) at specific positions (R1-R6) of the imidazolidinylide core to locally modify electronic properties and increase voltage tolerance without affecting the overall shut-down mechanism or introducing toxicity.
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 imidazolidinylide compounds provide effective shut-down at defined potentials, forming a passivation layer to block ion transport, enabling higher working voltages without impacting cell cycling and reducing toxicity risks.
Implementation Method 1
The imidazolidinylide compounds provide effective shut-down at defined potentials, forming a passivation layer to block ion transport
Implementation Method 2
forming a passivation layer to block ion transport
Data Source
AI summary
An imidazolidinylide compound for use as a shut-down additive for a lithium-ion battery. The imidazolidinylide compound has a formula (I),wherein, R1 to R4, each independently the other, is a linear C1- to C16-alkyl group, a branched C1- to C16-alkyl group, a C2- to C16-alkenyl group, a C3- to C8-cycloalkyl group, or a C3- to C16-arene group, wherein at least one of R2 and R3 may also be H, R1 to R4, each independently of the other, is completely, partially or not fluorinated, and R1 to R3 may each also contain O as a heteroatom.