Coated Cathode Additive for Lithium Batteries Without Slurry Gelation
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Solution Overview
Problem
The non-reversible efficiency difference between positive and negative electrodes in lithium secondary batteries leads to unnecessary waste of positive electrode material and challenges in achieving high energy density, with existing additives like Li2NiO2 causing issues such as slurry gelation and gas generation.
Innovation Solution
A positive electrode additive represented by Chemical Formula 1, Li6xCo1-yMyO4, where 0.9≤x≤1.1 and 0<y≤0.1, doped with boron (B) and tungsten (W), is used to improve the non-reversible capacity of the negative electrode, reducing gelation and gas generation issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Li2NiO2 is added as a positive electrode additive to improve non-reversible capacity, then the non-reversible efficiency of the negative electrode is improved, but slurry gelation occurs due to residual lithium and Ni elution continues during charge-discharge cycles
Solution Approach 1:
A coating layer comprising at least one of boron (B) and tungsten (W) is applied to the surface of the Li2NiO2 additive particles. This coating layer acts as an intermediary barrier that prevents residual lithium from causing slurry gelation and stops nickel elution during charge-discharge cycles, while still allowing the additive to improve non-reversible capacity.
Solution Approach 2:
The surface properties of the Li2NiO2 additive are modified by coating with boron and/or tungsten compounds. This changes the chemical and physical parameters of the additive surface, reducing its reactivity with the slurry components and electrolyte, thereby preventing gelation and gas generation while maintaining the desired electrochemical function.
2Reliability
If the amount of positive active material is increased to compensate for non-reversible efficiency loss, then battery efficiency is maintained, but the energy density of the battery decreases due to excessive negative active material input
Solution Approach 1:
The coated Li2NiO2 additive serves as an intermediary that enables the negative electrode to achieve higher non-reversible efficiency (close to 100%). This allows the battery to maintain high overall efficiency without requiring excessive positive active material, thereby preserving energy density.
3Quantity of substance
If carbon-based negative active material is reduced to achieve high energy density with high-nickel lithium composite oxide, then energy density improves, but it becomes difficult to design the battery efficiently due to mismatched non-reversible efficiencies
Solution Approach 1:
The coated Li2NiO2 additive acts as a design tool that enables efficient battery configuration. By improving the non-reversible efficiency of the negative electrode to match the positive electrode, it allows for optimized electrode ratios and simplified battery design while achieving high energy density with high-nickel lithium composite oxide.
Data Source
AI summary
The present disclosure relates to a positive electrode additive for a lithium secondary battery, a manufacturing method thereof. The positive electrode additive for a lithium secondary battery is represented by Chemical Formula 1 below.Li6xCo1-yMyO4 [Chemical Formula 1](In the Chemical Formula 1, 0.9≤x≤1.1, 0<y≤0.1, My=BaWb, 0≤a≤0.1, 0≤b≤0.1, and, a and b are not simultaneously 0.)Another positive electrode additive for a lithium secondary battery includes a core represented by Chemical Formula 2 below; and a coating layer comprising at least one of boron (B) and tungsten (W).Li6xCoO4 [Chemical Formula 2](In the Chemical Formula 2, 0.9≤x≤1.1.)