Positive Electrode Pre-Dispersion for Low-Additive Slurry Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges with the dispersibility and electrical properties due to the use of low amounts of irreversible additives, leading to reduced charging and discharging efficiency and safety concerns.
Innovation Solution
A pre-dispersion for a positive electrode containing a specific lithium cobalt oxide-based additive, conductive materials, and a binder, optimized to improve dispersibility and minimize side reactions, is used in the lithium secondary battery, ensuring high content and stability of the additive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a low content of irreversible additive is used, then the cost is reduced, but the dispersibility in positive electrode slurry deteriorates and electrical properties are lowered
Solution Approach 1:
The patent applies preliminary action by pre-dispersing the irreversible additive (Li6CoO4) in a binder solution before mixing with other slurry components. This pre-dispersion step ensures uniform distribution of the additive at low concentrations (0.1-5 wt%), preventing aggregation and maintaining electrical properties while reducing the required additive content.
Solution Approach 2:
The patent uses a binder (PVDF, CMC, or SBR) as an intermediary medium to disperse the irreversible additive. The binder acts as a mediator that facilitates uniform distribution of the additive particles in the slurry, ensuring good dispersibility and electrical conductivity even at low additive concentrations.
2Quantity of substance
If a low content of irreversible additive is used, then the cost is reduced, but the degree of freedom of process design is lowered due to scattering and increased loss amount
Solution Approach 1:
The pre-dispersion step is performed before the main slurry mixing process, which prevents scattering of fine additive particles during subsequent handling and coating operations. This preliminary preparation ensures the additive remains uniformly distributed, reducing loss during manufacturing and maintaining process flexibility.
Solution Approach 2:
The binder serves as an intermediary that binds the fine irreversible additive particles together, preventing scattering during the coating and drying processes. This reduces material loss and simplifies the manufacturing process by eliminating the need for complex anti-scattering measures.
3Quantity of substance
If conventional irreversible additive Li6CoO4 is used in high content, then the irreversible capacity is improved, but the structural stability deteriorates and oxygen gas generation increases
Solution Approach 1:
The patent changes the concentration parameter of the irreversible additive from high content to low content (0.1-5 wt%), and compensates by optimizing the pre-dispersion process. This parameter change maintains the necessary irreversible capacity while improving structural stability and reducing oxygen gas generation during charging.
Solution Approach 2:
The pre-dispersion process ensures uniform distribution of the irreversible additive, which prevents localized concentration effects that could lead to structural instability and excessive oxygen generation. This preliminary uniform distribution allows the use of lower overall additive content while maintaining performance.
Data Source
AI summary
A pre-dispersion for a positive electrode and a positive electrode slurry for a lithium secondary battery containing the same are disclosed herein. In some embodiments, a pre-dispersion comprises a positive electrode additive represented by the following Chemical Formula 1, a first conductive material, a binder:LipCo(1-q)M1qO4 [Chemical Formula 1]wherein M1 is one or more elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, 5≤p≤7, and 0≤q≤0.5. Dispersibility and workability of the positive electrode additive in the positive electrode slurry are improved. Side reactions that may be generated in the preparation of the positive electrode slurry can be suppressed while minimizing the loss of the positive electrode additive, so that the electrical properties of the electrodes manufactured using the same are improved.