Nickel-Rich NMC Cathode Phosphate Coating for Aged Storage Stability
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Solution Overview
Problem
Aged nickel-rich NMC cathode materials for lithium-ion secondary batteries exhibit an overpotential peak during the formation process, which affects the quality control and increases storage costs due to the need for dry conditions to prevent surface reactions, limiting their storage time and efficiency.
Innovation Solution
A method involving the formation of a cathode with aged nickel-rich NMC material, binder, and carbon black, followed by exposure to diethyl phosphoramidate at elevated temperatures to form a lithium phosphate protective layer, using an atomic layer deposition technique to enhance storage stability and reduce surface impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If nickel-rich NMC cathode material is stored in dry conditions to prevent surface reactions, then material stability is improved, but storage cost and facility complexity increase
Solution Approach 1:
The patent applies preliminary action by forming a protective coating on the cathode material surface before storage. This pre-protection layer prevents surface reactions with atmospheric moisture, eliminating the need for complex dry storage facilities. The coating is applied in advance during manufacturing, allowing the material to be stored in normal atmospheric conditions without degradation.
2Loss of time
If nickel-rich NMC cathode material is stored for extended periods, then production flexibility is improved, but material performance deteriorates due to surface reactions
Solution Approach 1:
The protective coating is applied in advance before storage, creating a barrier that prevents surface reactions during extended storage periods. This preliminary protection maintains material performance regardless of storage duration, enabling flexible production scheduling without performance degradation.
Solution Approach 2:
The patent changes the surface chemistry parameters of the cathode material by applying a protective coating with different chemical properties. This modification alters the surface reactivity, making it resistant to atmospheric moisture and oxygen, thereby maintaining performance during long-term storage.
3Device complexity
If aged nickel-rich NMC cathode material is used, then storage cost is reduced, but overpotential peak appears during formation process
Solution Approach 1:
The protective coating is applied before storage, preventing surface reactions that would otherwise occur during storage. This pre-protection eliminates the formation of surface impurities and hydroxides that cause overpotential peaks, allowing the material to be stored in cost-effective normal conditions without generating harmful effects during subsequent use.
Solution Approach 2:
The patent converts the potential harm of surface reactions into a benefit by using the storage period to allow complete drying of the coating applied during manufacturing. The extended storage time, which would normally cause degradation, is instead used to optimize the coating's protective properties, eliminating overpotential peaks.
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 lithium phosphate protective layer improves the cathode's performance by increasing capacity, reducing charge transfer and total resistance, and minimizing the overpotential peak, allowing longer storage in non-humidified conditions while maintaining efficiency.
Implementation Method 1
exposing the cathode to diethyl phosphoramidate at an exposure temperature above 160° C. so as to obtain a lithium phosphate protective layer on the cathode
Data Source
AI summary
Method for restoration performances of aged nickel-rich NMC cathode material for lithium-ion secondary battery, the method including: forming a cathode with the aged nickel-rich NMC cathode material and carbon black; and exposing the cathode to diethyl phosphoramidate at an exposure temperature below 160° C. so as to obtain a lithium phosphate protective layer on the cathode.