Nickel-Substituted Spinel Cathode Coating for High Voltage Stability
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Solution Overview
Problem
Lithium secondary batteries with LiMn2O4 have low energy density and high voltage substitution with nickel leads to electrolyte decomposition and performance deterioration due to side reactions.
Innovation Solution
A cathode active material comprising spinel-type compound particles with metal oxides or hydroxides on their surfaces, specifically Li1+aNibMn2-(b+c)O4-z, where M is Ti, Co, Al, etc., and the metal oxides/hydroxides form a protective layer to suppress manganese elution and electrolyte reactions, enhancing energy density and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel substitutes manganese in LiMn2O4 to improve energy density, then energy density increases, but electrolyte decomposition and side reactions occur due to high operating potential
Solution Approach 1:
A protective coating layer comprising metal oxide particles or metal hydroxide particles (or their composite) is applied on the surface of the spinel-type compound particles. This intermediary layer prevents direct contact between the high-potential cathode material and the electrolyte, thereby suppressing side reactions and electrolyte decomposition while maintaining the high energy density benefits of nickel-substituted spinel.
Solution Approach 2:
The invention uses composite materials consisting of spinel-type compound particles (Li1+aNibMn2-(b+c)O4-z) coated with metal oxide or metal hydroxide particles. This composite structure combines the high energy density characteristics of nickel-substituted spinel with the protective properties of metal oxide/hydroxide coatings, resolving the contradiction between energy density improvement and electrolyte stability.
2Quantity of substance
If nickel substitutes manganese in LiMn2O4 to improve energy density, then energy density increases, but manganese elution occurs leading to performance deterioration
Solution Approach 1:
The metal oxide or metal hydroxide coating acts as a protective barrier that prevents manganese elution from the spinel structure. This intermediary layer stabilizes the cathode material composition during charge-discharge cycles at high potentials, preventing manganese dissolution into the electrolyte while preserving the high energy density properties.
Solution Approach 2:
The invention modifies the surface properties of the spinel-type compound by coating it with metal oxide or metal hydroxide particles. This parameter change in surface composition and structure prevents manganese elution while maintaining the bulk material's high energy density characteristics, thus resolving the contradiction between energy density improvement and compositional stability.
3Quantity of substance
If operating potential is increased to 4.6 V or more to improve energy density, then energy density increases, but electrolyte decomposition occurs
Solution Approach 1:
The metal oxide or metal hydroxide coating layer serves as a protective intermediary between the high-potential spinel cathode and the electrolyte. This coating enables the battery to operate at 4.6 V or higher potentials for improved energy density while preventing electrolyte decomposition that would otherwise occur at such high potentials.
Solution Approach 2:
The metal oxide or metal hydroxide coating creates an inert protective environment around the spinel-type compound particles, isolating the electrolyte from direct contact with the high-potential cathode material. This inert barrier allows high-voltage operation for enhanced energy density without the harmful electrolyte decomposition reactions.
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 solution achieves high energy density and stable charge/discharge cycles by preventing manganese elution and electrolyte side reactions, maintaining high voltage performance and increasing reversible capacity.
Implementation Method 1
the metal oxide or the metal hydroxide physically and/or chemically combines with the surface of the spinel-type compound
Data Source
AI summary
Disclosed are a cathode active material for high voltage and a lithium secondary battery including the same. More particularly, a cathode active material including spinel-type compound particles having a composition represented by Formula 1 below; and metal oxides or metal hydroxides present on surfaces of the spinel-type compound particles, and a lithium secondary battery including the same. L1+aMxMn2-xO4-zAz (1) where a, x and z are defined in a specification of the present invention.