Lithium Transition Metal Oxide Doped with +4 Cation for Stability
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Solution Overview
Problem
Lithium secondary batteries face limitations in structural stability, initial discharge capacity, lifespan characteristics, and voltage stability, particularly in high energy density applications, due to the instability of layered lithium transition metal oxides when charged.
Innovation Solution
A cathode active material is developed with a layered lithium transition metal oxide doped with a metal cation having an oxidation number of +4, disposed in the octahedral site of the transition metal oxide lattice, which improves structural stability and electrochemical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If layered LiCoO2 is used as cathode active material, then voltage stability is improved, but energy density and discharge capacity are limited to about 200 mAh/g or less
Solution Approach 1:
The patent changes the chemical composition parameters by introducing a metal element M (where M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, or Hf) into the LiCoO2 lattice structure. This substitution modifies the electronic and structural properties of the cathode material, enabling higher discharge capacity while maintaining voltage stability. The metal element content is controlled at 0.01-5 atom% to optimize both capacity and stability.
Solution Approach 2:
The patent creates a composite cathode active material with general formula Li1+x[M1-yMy]O2 (where 0 < x ≤ 0.5, 0 < y ≤ 1, and M is transition metal). This composite structure combines LiCoO2 with metal-doped regions, achieving synergistic effects that simultaneously improve discharge capacity beyond 200 mAh/g and maintain the voltage stability characteristic of LiCoO2.
2Quantity of substance
If LiNiO2 is used to provide high energy density, then discharge capacity is improved, but structural stability deteriorates and the battery becomes prone to failure
Solution Approach 1:
The patent applies local quality by selectively doping specific metal elements into specific regions of the cathode structure. The metal element M is incorporated at controlled concentrations (0.01-5 atom%) to locally reinforce the crystal structure where needed, providing structural stability support precisely at the locations where capacity enhancement occurs, thereby preventing overall structural degradation.
Solution Approach 2:
The patent modifies the stoichiometric parameters of LiNiO2 by introducing metal element M with controlled composition ratios (0 < x ≤ 0.5, 0 < y ≤ 1 in the formula Li1+x[M1-yMy]O2). These parameter changes optimize the balance between discharge capacity and structural stability, preventing the structural degradation that occurs in undoped LiNiO2 while maintaining high capacity.
3Use of energy by moving object
If the cathode active material is charged to high voltage for high energy density, then energy density is improved, but structural deformation occurs leading to failure
Solution Approach 1:
The patent implements beforehand cushioning by pre-doping the cathode active material with metal element M during material synthesis. This creates an inherently more stable crystal structure that can withstand the mechanical and chemical stresses of high-voltage charging without deforming. The metal doping acts as a preventive measure against structural failure during operation.
Solution Approach 2:
The patent creates a composite structure Li1+x[M1-yMy]O2 that combines the high energy density characteristics with enhanced structural resilience. The metal-doped composite maintains structural integrity at high voltages, enabling safe operation at elevated charge states for high energy density applications.
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 doped cathode active material enhances initial discharge capacity, lifespan, and voltage maintaining characteristics, maintaining structural integrity even at high voltages, thus improving the performance of lithium secondary batteries.
Implementation Method 1
a cathode active material includes a layered lithium transition metal oxide, wherein the layered lithium transition metal oxide includes a metal cation having an oxidation number of +4, wherein the metal cation is disposed in an octahedral site of a lattice of the transition metal oxide
Implementation Method 2
precipitating a transition metal hydroxide including a metal cation having an oxidation number of +4 from the combination
Implementation Method 3
thermally treating the mixture and heating the mixture to prepare the cathode active material
Data Source
AI summary
A cathode active material including a layered lithium transition metal oxide, wherein the layered lithium transition metal oxide includes a metal cation having an oxidation number of +4, and wherein the metal cation is disposed in an octahedral site of a lattice of the layered lithium transition metal oxide.