Positive Electrode Coating for High-Voltage Battery Stability
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in achieving high energy density, long cycle life, and stability of positive electrode active materials, particularly with lithium nickel oxide-based materials, which suffer from reduced discharge potential and volume density, and are prone to gas generation at high voltages.
Innovation Solution
A positive electrode active material is developed with a surface coating layer containing nickel and/or manganese on lithium and cobalt complex oxide particles, optimized through ESCA surface analysis to achieve specific binding energy values and peak intervals, enhancing stability and reducing cobalt elution, and featuring a composition represented by the formula LipNi(1-q-r-s)MnqCorM1sO(2-y), with a surface coating amount between 0.5 to 20 mole %.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the charge voltage is increased to 4.25 V or more to achieve high energy density, then the capacity increases, but the cycle life is lowered and high-temperature characteristics are deteriorated
Solution Approach 1:
The invention applies a surface coating layer containing nickel and/or manganese on the positive electrode active material particles. This creates a localized protective barrier at the particle surface that stabilizes the material during high-voltage charging, preventing degradation while maintaining high capacity. The coating layer specifically addresses the surface-related stability issues without compromising the bulk material's high energy density properties.
Solution Approach 2:
The invention uses composite positive electrode active materials with a core-shell structure, where the core contains lithium-containing transition metal compounds (such as LiCoO2, LiNi0.8Co0.1Mn0.1O2) and the shell contains nickel and/or manganese compounds. This composite structure combines the high capacity of the core with the stability of the shell, enabling operation at high voltages (4.25V or more) while maintaining good cycle life and high-temperature characteristics.
2Stability of the object's composition
If lithium nickel complex oxides are used to stabilize the positive electrode active material, then the stability at high potential is improved, but the discharge potential or volume density is lowered
Solution Approach 1:
The invention applies a surface coating layer containing nickel and/or manganese on the positive electrode active material particles. This creates a localized protective barrier at the particle surface that stabilizes the material during high-voltage charging, preventing degradation while maintaining high capacity. The coating layer specifically addresses the surface-related stability issues without compromising the bulk material's high energy density properties.
Solution Approach 2:
The invention uses composite positive electrode active materials with a core-shell structure, where the core contains lithium-containing transition metal compounds (such as LiCoO2, LiNi0.8Co0.1Mn0.1O2) and the shell contains nickel and/or manganese compounds. This composite structure combines the high capacity of the core with the stability of the shell, enabling operation at high voltages (4.25V or more) while maintaining good cycle life and high-temperature characteristics.
3Stability of the object's composition
If a coating layer containing nickel and/or manganese is formed on the surface, then cobalt elution is suppressed and stability is enhanced, but the manufacturing process complexity increases
Solution Approach 1:
The invention combines the coating formation and heat treatment steps into an integrated process. The coating layer containing nickel and/or manganese is formed on the positive electrode active material particles, followed by heat treatment to stabilize the coating and suppress cobalt elution. This integrated approach achieves enhanced stability while controlling manufacturing complexity by combining related operations.
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 results in a high-capacity battery with improved charge and discharge cycle retention and stability at high voltages, suppressing gas generation and maintaining energy density, suitable for portable electronic devices.
Implementation Method 1
a positive electrode active material for nonaqueous electrolyte secondary batteries, which includes a coating layer containing at least nickel (Ni) and/or manganese (Mn) on the surface of a complex oxide particle containing lithium (Li) and cobalt (Co)
Implementation Method 2
a binding energy value obtained by analysis of a surface state by an ESCA surface analysis on the surface of the coating layer is 642.0 eV or more and not more than 642.5 eV in an Mn2p3 peak
Data Source
AI summary
A positive electrode active material for nonaqueous electrolyte secondary batteries includes a coating layer containing at least nickel (Ni) and/or manganese (Mn) on the surface of a complex oxide particle containing lithium (Li) and cobalt (Co), wherein a binding energy value obtained by analysis of a surface state by an ESCA surface analysis on the surface of the coating layer is 642.0 eV or more and not more than 642.5 eV in an Mn2p3 peak, and a peak interval of Co—Mn is 137.6 eV or more and not more than 138.0 eV.