Phosphite Electrolyte Additives for Battery Safety
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Solution Overview
Problem
Lithium ion batteries face safety hazards due to the flammability of organic solvents in their electrolytes, which also lead to reduced electrochemical performance and capacity degradation over cycles.
Innovation Solution
An electrolyte composition containing at least 3 wt.% of specific phosphite compounds, such as dimethyl phosphite, combined with anode film-forming additives like vinylene carbonate, which significantly reduces flammability and enhances electrochemical performance by forming a passivation layer on the anode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic solvents are used in electrolytes to achieve high ionic conductivity, then electrochemical performance is improved, but flammability increases creating safety hazards
Solution Approach 1:
The patent introduces phosphite compounds as intermediary substances that mediate between the conflicting requirements of maintaining electrochemical performance and reducing flammability. These compounds form protective films on electrode surfaces, acting as a barrier that prevents direct contact between flammable electrolyte and oxygen, while still allowing ionic transport to maintain battery performance
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating phosphite compounds with specific molecular structures (formula I) containing P-H bonds. This parameter change transforms the electrolyte's flammability characteristics while maintaining its ionic conductivity through careful selection of R1, R2, and R3 substituents
2Object-affected harmful factors
If flame retardant compounds are added to reduce flammability, then safety is improved, but electrochemical performance and capacity retention deteriorate
Solution Approach 1:
The patent applies local quality by concentrating the flame retardant function at specific locations - the electrode surfaces - rather than uniformly throughout the entire electrolyte. The phosphite compounds preferentially adsorb and form protective films on anode and cathode surfaces, providing localized flame retardancy where it is most needed while leaving the bulk electrolyte composition optimized for ionic conductivity
Solution Approach 2:
The patent creates a composite electrolyte system combining conventional carbonate solvents (EC, DMC, DEC) with phosphite flame retardant additives. This composite formulation integrates the high ionic conductivity of carbonates with the flame retardant properties of phosphites, achieving both safety and performance requirements through synergistic material combination
3Object-affected harmful factors
If high concentrations of flame retardant are used to achieve quick self-extinguishment, then flammability is reduced, but device complexity and cost increase
Solution Approach 1:
The patent applies partial action by using sub-stoichiometric amounts of phosphite compounds - concentrations below what would be required for complete flame suppression - to achieve sufficient self-extinguishment performance. The protective films formed at these partial concentrations are adequate to quench flames, avoiding the need for complex high-concentration formulations
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 electrolyte composition achieves a substantial reduction in flammability, maintaining high reversible capacity and low capacity decrease over repeated cyclization, with the phosphite compounds acting as efficient flame retardants even at low concentrations.
Implementation Method 1
anode film forming additive which forms a passivation layer on the anode
Implementation Method 2
the vapor pressure of the compound of general formula (I) in the electrolyte composition is high. In this way, the presence of a high concentration of the compound of general formula (I) in the gas phase in case of a fire is ensured acting efficiently against the burning process
Data Source
AI summary
The present invention relates to an electrolyte composition with low flammability which can be used in batteries yielding high electrochemical performance. In particular, the present invention relates to an electrolyte composition comprising a) at least 3 wt.-% of the electrolyte composition of at least one compound of general structure (I) R1 and R2 are independent from each other methyl, ethyl, n-propyl or n-butyl and b) at least one anode film forming additive.