Doped NCM Cathode Material for Moisture-Stable Li-Ion Batteries
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Solution Overview
Problem
High nickel-containing lithium secondary battery positive electrode active materials face issues with moisture absorption, leading to reduced capacity and adhesion due to the formation of hydroxyl groups, which react with the binder, causing gelation and non-uniformity of the electrode layer.
Innovation Solution
A nickel-cobalt-manganese-based lithium transition metal oxide with specific doping elements such as aluminum, magnesium, and titanium is used, reducing moisture absorption by optimizing the composition and ratio of these elements to enhance structural stability and capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel content in the lithium composite transition metal oxide is increased to improve capacity characteristics, then the reversible capacity is enhanced, but the material becomes unstable and absorbs moisture from the air or electrolyte solution, forming hydroxyl groups that react with the binder to cause gelation and reduce adhesion
Solution Approach 1:
The patent applies local quality by substituting nickel with cobalt and manganese at specific positions in the crystal structure to create regions of different stability. The formula Li1+a[NixCoyMnz]O2 (where x+y+z=1 and 0.9≤x<1) shows that by controlling the local composition around nickel atoms, the material maintains high overall nickel content while creating stable local environments that prevent moisture absorption and hydroxyl group formation.
Solution Approach 2:
The patent uses composite materials by combining nickel, cobalt, and manganese in a specific ratio within the same crystal structure. This NCM-based lithium composite transition metal oxide leverages the high capacity of nickel while incorporating the stability of cobalt and manganese, creating a composite material that achieves both high reversible capacity and resistance to moisture absorption.
2Use of energy by moving object
If the nickel content is increased to achieve high energy density, then the capacity characteristics improve, but the hydroxyl groups formed react with the binder causing gelation and non-uniformity of the positive electrode active material layer
Solution Approach 1:
By controlling the local composition and oxidation state of nickel (maintaining Ni3+ without excessive Ni4+ formation), the patent prevents localized hydroxyl group formation that would cause gelation. The specific compositional control in Li1+a[NixCoyMnz]O2 ensures uniform distribution of stable metal centers throughout the material, preventing localized reactions with the binder.
3Reliability
If conventional NCM-based or NCA-based lithium composite transition metal oxides are used with lower nickel content to maintain stability, then the material stability is preserved, but the capacity characteristics become insufficient for high-performance applications
Solution Approach 1:
The patent changes the compositional parameters by increasing nickel content to x≥0.9 while adjusting cobalt and manganese content accordingly (y+z≤0.1). It also changes the lithium stoichiometry parameter a to control the overall composition. These parameter changes enable the material to achieve both high capacity (due to high nickel) and high stability (due to optimized cobalt/manganese content and lithium excess), resolving the trade-off between capacity and 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 approach effectively suppresses moisture absorption, improves capacity characteristics, and maintains electrode adhesion, resulting in enhanced energy density and extended battery life.
Implementation Method 1
a nickel-cobalt-manganese-based lithium transition metal oxide which contains nickel in an amount of 60 mol % or more based on a total number of moles of metals excluding lithium
Data Source
AI summary
In one arrangement, the present disclosure relates to a positive electrode active material including a nickel-cobalt-manganese-based lithium transition metal oxide which contains nickel in an amount of 60 mol % or more based on a total number of moles of metals excluding lithium, wherein the nickel-cobalt-manganese-based lithium transition metal oxide is doped with doping element M1 (where the doping element M1 is a metallic element including Al) and doping element M2 (where the doping element M2 is at least one metallic element selected from the group consisting of Mg, La, Ti, Zn, B, W, Ni, Co, Fe, Cr, V, Ru, Cu, Cd, Ag, Y, Sc, Ga, In, As, Sb, Pt, Au, and Si), where the doping element M1 can be in an amount of 100 ppm to 10,000 ppm, and the doping element M1 and the doping element M2 are included in a weight ratio of 50:50 to 99:1.