Lithium Battery Electrolyte Additive Ratio Optimization
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries for vehicle drive power sources face challenges in optimizing the amount of boron-containing lithium salts added to achieve sufficient anode protection and capacity-deterioration suppression, leading to inefficient use of materials and economic concerns.
Innovation Solution
Incorporating a specific compound represented by formula (1) in the non-aqueous electrolyte, with an initial content ratio of 0.04 to 0.5 (mol/kg)/(mF/cm2), which is reduced and decomposed on the anode to form a chemically stable coating, optimizing anode protection and capacity maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of boron-containing lithium salt is increased to ensure sufficient anode protection and capacity-deterioration suppression, then the cycle characteristics and durability are improved, but the material cost increases unnecessarily
Solution Approach 1:
The patent changes the parameter of additive concentration specification from conventional methods (concentration in electrolyte or molar ratio relative to LiPF6) to a new parameter: the ratio of additive amount to anode active material amount (mmol/g). This parameter change enables precise optimization of the coating formation process, ensuring sufficient anode protection while minimizing additive usage and material cost.
2Stability of the object's composition
If the amount of boron-containing lithium salt is defined by concentration or molar ratio, then the electrolyte composition is controlled, but the chemical and physical relationship between anode and coating formation becomes unclear, making optimization difficult
Solution Approach 1:
The patent introduces an intermediary parameter (the ratio of additive amount to anode active material amount) that bridges the gap between electrolyte composition control and coating formation optimization. This intermediary parameter makes the relationship between anode and coating formation quantifiable and controllable, resolving the difficulty of optimization.
3Quantity of substance
If boron-containing lithium salt is not added in sufficient amount, then material cost is reduced, but the anode protecting effect and capacity-deterioration suppressing effect are insufficient
Solution Approach 1:
The patent applies partial action by determining the precise minimum amount of boron-containing lithium salt needed for effective coating formation, based on the anode active material amount. This avoids both insufficient addition (which would compromise protection) and excessive addition (which would increase cost unnecessarily), achieving optimal balance through the specified ratio range.
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
This approach enhances the cycle characteristics and durability of the battery while optimizing the use of additives, reducing material costs and improving economic efficiency by ensuring sufficient anode protection and capacity maintenance.
Implementation Method 1
the compound represented by formula (1) below... is reduced and decomposed on the anode
Implementation Method 2
the compound represented by formula (1) below... is reduced and decomposed on the anode
Implementation Method 3
a coating consisting of a chemically stable compound (for example, a polymerization compound of LiBOB) is formed on the anode
Data Source
AI summary
A lithium secondary battery 100 is configured such that an electrode body 20, in which a cathode and an anode are stacked via a separator impregnated with an electrolyte, is housed in a battery case 10 having a substantially cylindrical square shape and that an opening 12 of the case 10 is blocked by a lid 14. Further, the lid 14 is provided with a cathode terminal 38 and an anode terminal 48, and such terminals are respectively connected, inside the battery case 10, to an internal cathode collection terminal 37 and an internal anode collection terminal 47. A non-aqueous electrolyte used for the lithium secondary battery 100 contains, as a specific compound, for example, LiBOB, and an initial content of such specific compound relative to a capacitance of the anode is 0.04 to 0.5 [(mol/kg)/(mF/cm2)].