LLZO-Shell NMC Cathode Material for Capacity Retention
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Solution Overview
Problem
Current cathode materials for lithium-ion batteries, such as lithium nickel manganese cobalt oxide, face issues with irreversible capacity loss and reduced electrochemical efficiency due to cation mixing and reactions with electrolyte solutions, leading to decreased battery performance and stability.
Innovation Solution
A core-shell structured cathode active material is developed, where the core is lithium nickel manganese cobalt oxide and the shell is lithium lanthanum zirconate, with a mass ratio of 90-99 to 1-10, enhancing lithium-ion conductivity and preventing reactions with the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium nickel manganese cobalt oxide material is used as cathode active material, then high capacity is achieved, but irreversible capacity loss occurs due to cation mixing and reaction with electrolyte solution
Solution Approach 1:
The invention uses a core-shell composite structure where the core is lithium nickel manganese cobalt oxide (NMC) material and the shell is lithium lanthanum zirconate (LLZO) solid electrolyte. This composite structure allows the high-capacity NMC core to be protected by the LLZO shell, which prevents cation mixing and reduces irreversible capacity loss while maintaining good electrochemical performance and long cycle life
Solution Approach 2:
The lithium lanthanum zirconate (LLZO) solid electrolyte shell acts as an intermediary layer between the NMC cathode material and the liquid electrolyte. This intermediate shell prevents direct contact and harmful reactions between the NMC material and the liquid electrolyte, thereby reducing irreversible capacity loss and improving battery reliability
2Stability of the object's composition
If conventional coating materials (Al2O3, MgO, TiO2, MnO2, ZrO2) are used to improve cathode material surface, then structure stability is increased, but conductivity is reduced
Solution Approach 1:
The invention changes the material parameter from conventional oxide coatings to lithium lanthanum zirconate (LLZO) solid electrolyte, which has inherently high ionic conductivity. This parameter change allows the coating to maintain structure stability while avoiding the conductivity loss associated with traditional coating materials, thereby reducing energy loss
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 configuration improves charge-discharge efficiency, extends battery cycle life, and maintains high capacity retention, addressing the limitations of previous coatings with low conductivity materials.
Implementation Method 1
the shell is lithium lanthanum zirconate... reducing contact between the energy storage material and the electrolyte solution
Implementation Method 2
improves charge-discharge efficiency... enhancing lithium-ion conductivity
Data Source
AI summary
The present invention relates to a cathode active material for a lithium-ion battery having a structure comprising a core and a shell, wherein the core comprises lithium nickel manganese cobalt oxide compound, and the shell is lithium lanthanum zirconate (LLZO) with a mass ratio of core to shell in a range of 90-99 to 1-10. Furthermore, the present invention relates to a method for preparing said active material and to the cathode of the battery comprising the said active material and a method for preparing the said cathode. The invention also relates to a battery comprising said cathode. The lithium-ion battery having the cathode comprising the active material according to the present invention has an improved charge-discharge efficiency and good stability.