Non-aqueous Electrolyte Additives for Lithium-ion Battery Cycle Life
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Solution Overview
Problem
Current lithium-ion battery technologies face challenges in achieving balanced improvements in energy density, cycling performance, and electrochemical properties across various temperatures, with existing additives often increasing costs and having limited effects on multiple properties.
Innovation Solution
A non-aqueous electrolyte for lithium batteries comprising a combination of inorganic salts (Li2CO3, Li2SO4, LiNO3), vinylene carbonate (VC), and ethyl sulfite (ES) or propylene sulfite (PS) additives, optimized in specific weight percentages, to enhance low-temperature performance, cycle life, and capacity while reducing gas swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single additives (VC, ES, PS) are added to electrolyte, then certain properties (cycle life, co-intercalation suppression, SEI stability) are improved, but overall performance across multiple properties remains insufficient and cost increases
Solution Approach 1:
The patent combines multiple additives (VC, ES/PS, and inorganic salts like Li2CO3 or Li2SO3) into a single electrolyte formulation. This synergistic combination achieves comprehensive improvement in cycle life, capacity retention, and electrochemical stability across temperature ranges, while using smaller amounts of each component compared to single-additive approaches, thereby controlling costs.
Solution Approach 2:
The electrolyte uses a composite additive system comprising organic additives (VC, ES/PS) and inorganic additives (Li2CO3, Li2SO3, LiNO3) in specific weight ratios. This composite approach creates a more robust and stable SEI membrane with enhanced mechanical strength and chemical stability, improving overall battery reliability without proportionally increasing cost.
2Reliability
If higher amounts of additives are used to improve battery properties, then electrochemical performance improves, but manufacturing cost increases significantly
Solution Approach 1:
The patent optimizes the weight percentages of each additive component within specific ranges: VC (0.5-5%), ES or PS (0.1-5%), and inorganic salts (0.1-5%). By precisely controlling these parameters and their ratios, the formulation achieves maximum electrochemical performance with minimal additive quantities, avoiding the cost increase associated with higher additive loads.
Solution Approach 2:
The inorganic salt additives (Li2CO3, Li2SO3) act as intermediaries that facilitate the formation of stable SEI membranes at lower concentrations. These inorganic components work synergistically with organic additives to enhance membrane stability and electrochemical performance, allowing reduced overall additive usage while maintaining or improving battery reliability.
3Reliability
If existing additives are used to improve specific properties, then that property improves, but other properties remain unaffected or improve minimally
Solution Approach 1:
The patent employs a multi-functional additive system where each component contributes to multiple performance aspects: VC forms the base SEI structure, ES/PS suppress co-intercalation and enhance high-temperature stability, and inorganic salts (Li2CO3, Li2SO3) strengthen the membrane and improve low-temperature performance. This universal approach ensures simultaneous improvement in cycle life, capacity retention, temperature stability, and gas suppression.
Solution Approach 2:
The additive combination creates localized functional zones within the SEI membrane: the organic additives (VC, ES/PS) provide baseline stability and co-intercalation suppression, while inorganic additives concentrated at specific interfaces enhance mechanical strength and ionic conductivity. This spatial differentiation of functions within the membrane structure achieves comprehensive performance improvement across all critical properties.
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 solution significantly increases battery capacity, maintains 80% residual capacity after 400 cycles, and reduces gas generation, with improved performance at low temperatures and higher discharge capacity compared to batteries without additives.
Implementation Method 1
The reduction potential of VC is higher than that of the solvents including ethylene carbonatediethyl carbonate (EC), PC, diethyl carbonate (DEC), dimethyl carbonate (DMC), etc. Thus VC can be reduced first on a carbon negative electrode and forms stable SEI membrane
Implementation Method 2
the SEI membrane (formed in the reactions between active matters and the electrolyte during the initial charging process) can suppress solvent from co-intercalating into the graphite and has no negative effects on the transmission of Li+
Implementation Method 3
by adding vinylene carbonate (VC), a passivation film can be formed on the surface of electrodes
Data Source
AI summary
This invention relates to non-aqueous electrolytes, in particular, a non-aqueous electrolyte for lithium-ion secondary batteries. The electrolyte comprises regular organic solvents and electrolyte saline. The special characteristics are: the electrolyte also comprises mixed additives, said mixed additives comprising at least one of those of compound group A, at least one of those of compound group B, and one of those of compound group C wherein: compound group A are selected from inorganic saline including Li2CO3, Li2SO4, Li2SO3, LiNO3; compound group B are selected from vinylene carbonate, propylene carbonate; and compound group C are selected from ES, PS, DMS, DES, DMSO. The weight ratio can be A:B:C=0.1%-3.0%:0.5%-4.0%:1.0%-5.0%.