Lithium-Ion Cathode Paste Hydroxide Additives for Al Foil Corrosion
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Solution Overview
Problem
Lithium-ion secondary batteries with aluminum current collecting foils face corrosion issues during high-load energization, leading to aluminum liquation and potential internal short-circuits due to insufficient AlF3 coating at the initial stage of use.
Innovation Solution
Incorporating hydroxide particles, such as LiOH, into the positive electrode paste to promote the formation of a high-corrosion-resistant AlF3 coating on the aluminum current collecting foil during the battery production process, especially during initial charging, which enhances the coating formation reaction and reduces aluminum liquation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-load energization is performed at the initial stage of use, then power output is improved, but aluminum liquation occurs due to insufficient AlF3 coating
Solution Approach 1:
The patent applies preliminary action by adding hydroxide particles to the positive electrode paste before battery assembly, enabling the AlF3 coating formation to begin during initial charging rather than waiting for operational degradation. This preliminary chemical preparation ensures the coating exists before high-load energization occurs, resolving the contradiction between immediate power output and corrosion resistance.
Solution Approach 2:
The patent changes the chemical parameters of the positive electrode by incorporating hydroxide particles (such as LiOH) into the electrode paste formulation. This parameter change enables in-situ generation of AlF3 coating through chemical reaction during initial charging, transforming the electrode's protective characteristics before the battery enters service, thereby ensuring both power output and corrosion resistance from the start.
2Reliability
If AlF3 coating is formed to prevent corrosion, then corrosion resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies self-service by enabling the positive electrode to generate its own AlF3 coating through the chemical reaction between hydroxide particles and aluminum current collector during initial charging. This self-forming mechanism eliminates the need for external coating equipment or additional manufacturing steps, maintaining manufacturing simplicity while achieving superior corrosion resistance.
Solution Approach 2:
The hydroxide particles act as an intermediary substance that facilitates the formation of AlF3 coating. By introducing this intermediate chemical agent into the electrode paste, the system enables coating formation through simple mixing and initial charging, avoiding complex manufacturing processes while ensuring reliable corrosion protection.
3Reliability
If expensive additives like LiBF4 and LiFOB are added to promote AlF3 coating formation, then corrosion resistance is improved, but production cost increases
Solution Approach 1:
The patent replaces expensive additives (LiBF4 and LiFOB) with inexpensive hydroxide particles that serve the same protective function. The hydroxide particles are consumed during initial charging to form the AlF3 coating, acting as a disposable sacrificial material that enables corrosion protection without the high cost associated with conventional additives.
Solution Approach 2:
The patent changes the chemical composition parameter of the electrolyte system by substituting expensive fluoride-based additives with inexpensive hydroxide particles. This parameter substitution maintains the ability to form protective AlF3 coating while dramatically reducing material costs, making the corrosion protection solution economically viable.
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 method effectively increases the corrosion resistance of the aluminum current collecting foil, preventing aluminum liquation during high-load energization at the initial stage of use, thereby reducing the risk of internal short-circuits and improving battery reliability.
Implementation Method 1
In the process of the positive-electrode-paste producing, the hydroxide particles are further mixed in addition to the positive active material particles and the solvent
Implementation Method 2
promote the formation of a high-corrosion-resistant AlF3 coating on the aluminum current collecting foil during the battery production process, especially during initial charging
Implementation Method 3
there is a case that some local points on the positive current collecting foil could exhibit high potential. Then, these local points with high potential could be corroded to bring about liquation of Al (aluminum) from surfaces of those points
Implementation Method 4
these local points with high potential could be corroded to bring about liquation of Al (aluminum) from surfaces of those points
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A producing method for a lithium-ion secondary battery includes a positive-electrode-paste producing step (S1) of producing a positive electrode paste (63P) by mixing positive active material particles (64) with a solvent (69), a positive-electrode-plate producing step (S2) of applying and drying the positive electrode paste (63P) on a surface (61b, 61c) of a positive current collecting foil (61) to produce a positive electrode plate (60), an electrode body producing step (S3) of producing an electrode body (50) having the positive electrode plate (60) and a negative electrode plate (70), a housing step (S4) of housing the electrode body (50) in a battery case (30), an injecting step (S5) of injecting non-aqueous electrolytic solution (90) in the battery case (30) housed with the electrode body (50) to produce an injection-completed battery (1B), and an initial charging step (S6) of initially charging the injection-completed battery (1B). The positive-electrode-paste producing step (S1) is to produce the positive electrode paste (63P) in which hydroxide particles (67) are further mixed.