Nickel-Rich NMC Cathode Phosphate Coating for Air-Stable Storage
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Solution Overview
Problem
The reactivity of nickel-rich NMC cathode materials with atmospheric conditions leads to an overpotential peak during the first charge/discharge cycle, affecting cell production and increasing storage costs due to the need for dry conditions to prevent surface modification, which is undesirable.
Innovation Solution
A method involving the use of diethyl phosphoramidate to form a lithium phosphate protective layer on the cathode at elevated temperatures through atomic layer deposition, reducing the reactivity of aged nickel-rich NMC cathodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If nickel-rich NMC cathode material is stored in normal atmospheric conditions, then storage cost is reduced, but the material surface reacts with atmospheric conditions causing overpotential peak during formation process
Solution Approach 1:
The patent applies preliminary action by forming a protective coating on the nickel-rich NMC cathode material surface before storage or use. This coating is applied in advance to prevent the harmful reaction between the nickel-rich surface and atmospheric conditions, thereby avoiding the overpotential peak during the formation process while allowing storage in normal atmospheric conditions.
Solution Approach 2:
The patent uses an intermediary substance (protective coating) that acts as a barrier between the nickel-rich NMC cathode material and the atmospheric environment. This intermediary layer prevents direct contact and reaction between the reactive cathode surface and atmospheric components, eliminating the harmful effects while maintaining storage simplicity.
2Stability of the object's composition
If nickel-rich NMC cathode material is stored under dry conditions, then surface modification is reduced, but storage facility cost increases
Solution Approach 1:
The patent applies preliminary action by pre-coating the cathode material surface with a protective layer before storage. This preliminary protection enables the material to be stored in normal atmospheric conditions without requiring expensive dry storage facilities, while still maintaining surface composition stability and preventing overpotential peak formation.
Solution Approach 2:
The protective coating serves as an intermediary barrier that shields the nickel-rich NMC surface from atmospheric moisture and contaminants. This intermediary layer allows storage in cost-effective normal atmospheric conditions while maintaining surface stability, eliminating the need for expensive controlled environment storage facilities.
3Quantity of substance
If nickel content in NMC is increased to improve energy density, then specific capacity increases, but reactivity with atmospheric conditions increases
Solution Approach 1:
The patent applies local quality by modifying only the surface region of the nickel-rich NMC cathode material with a protective coating, while maintaining the bulk high-nickel composition that provides high specific capacity. This localized surface treatment preserves the desired high energy density properties while eliminating the harmful atmospheric reactivity at the surface.
Solution Approach 2:
The protective coating acts as an intermediary layer that allows the bulk material to maintain high nickel content for high specific capacity, while the coating itself provides the barrier function to prevent atmospheric reactivity. This enables the system to simultaneously achieve high energy density and atmospheric stability.
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 enhances the storage time of nickel-rich NMC cathodes without dry storage facilities, improving capacity and reducing charge transfer and total resistance while minimizing the overpotential peak.
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
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AI summary
Method (100) for restoration performances of aged nickel-rich NMC cathode material for lithium-ion secondary battery, the method (100) including: forming (110) a cathode with the aged nickel-rich NMC cathode material and carbon black; and exposing (114) the cathode to diethyl phosphoramidate at an exposure temperature below 160°C so as to obtain a lithium phosphate protective layer on the cathode