Dual-Electrolyte Lithium-Ion Battery for SEI Repair and Low DC Resistance
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Solution Overview
Problem
Current lithium-ion batteries fail to meet the higher requirements for initial direct current resistance and battery life, particularly in electric vehicles, leading to 'mileage anxiety' due to insufficient cruising ability.
Innovation Solution
A lithium-ion battery design incorporating a first and second electrolytic solution, where the mass ratio of additives in each solution is optimized to reduce initial direct current resistance and prolong battery life, with the first solution containing additives like vinylene carbonate and the second solution using film-forming additives to repair the Solid Electrolyte Interphase (SEI) film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single electrolytic solution is used in conventional lithium-ion batteries, then the manufacturing process is simple and cost-effective, but the initial direct current resistance is high and battery life is insufficient
Solution Approach 1:
The electrolytic solution is divided into two distinct components: a first electrolytic solution containing film-forming additives (vinylene carbonate, fluoroethylene carbonate) that forms the initial SEI layer, and a second electrolytic solution containing repair reforming additives (lithium difluorobisoxalato phosphate, lithium bis(oxalato)borate, lithium difluorophosphate) that repairs and stabilizes the SEI layer during cycling. This segmentation allows each component to perform its specific function optimally, resolving the contradiction between battery life improvement and structural complexity.
2Reliability
If the additive content in the first electrolytic solution is increased to improve SEI repair reforming, then the SEI stability is improved, but the initial direct current resistance becomes too large
Solution Approach 1:
The patent precisely controls the additive content parameters: the first electrolytic solution contains 1-4 wt% film-forming additives, and the second electrolytic solution contains 3-15 wt% repair reforming additives. The mass ratio relationship [(d2×t2)/(d1×t1)] between the two solutions is maintained within 0.1-11. These parameter optimizations ensure sufficient SEI repair reforming while preventing excessive initial direct current resistance, resolving the technical contradiction.
3Duration of action of stationary object
If the second electrolytic solution contains high amounts of film-forming additives to ensure service life consumption, then battery life is extended, but the manufacturing cost increases
Solution Approach 1:
The patent optimizes the additive concentration in the second electrolytic solution to 3-15 wt%, with the mass ratio [(d2×t2)/(d1×t1)] between 0.1-11 relative to the first electrolytic solution. This parameter optimization ensures adequate film-forming additive content for service life consumption while controlling manufacturing costs, resolving the contradiction between extended service life and manufacturing cost.
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 optimized electrolyte composition results in a lithium-ion battery with low initial direct current resistance and extended service life, ensuring improved performance and reduced costs.
Implementation Method 1
The initial formation of the SEI occurs in a formation process during the manufacturing process of the battery
Implementation Method 2
The electrolytic solution (i.e., the first electrolytic solution) remaining in the electrode assembly is still be consumed during an early using stage of the battery to carry out the repair reforming on the SEI
Implementation Method 3
the additive of the second electrolytic solution needs to be consumed to repair the SEI film, to prevent side reactions from continuously occurring at the active sites
Data Source
AI summary
The present disclosure relates to a lithium-ion battery including a first electrolytic solution and a second electrolytic solution. The first electrolytic solution and the second electrolytic solution satisfies 0.1≤[(d2×t2)/(d1×t1)]≤11, where d1 is a mass of the first electrolytic solution, d2 is a mass of the second electrolytic solution, t1 is a ratio of a mass of an additive of the first electrolytic solution to a mass of the first electrolytic solution, and t2 is a ratio of a mass of an additive of the second electrolytic solution to a mass of the second electrolytic solution.