High-Ni Cathode Composition for Longer-Cycle Non-Aqueous Batteries
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Solution Overview
Problem
Lithium transition metal oxides with high Ni content used in positive electrode active materials for non-aqueous electrolyte secondary batteries face issues with structural degradation during charge/discharge cycles, leading to reduced battery capacity and poor charge/discharge cycle characteristics.
Innovation Solution
Incorporating specific amounts of Ca and Al into the lithium transition metal oxide to stabilize the layered structure, forming a protective film on the negative electrode surface, and optimizing the composition and calcination process to maintain structural integrity and improve cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium transition metal oxide with high Ni content is used as positive electrode active material, then battery energy density is improved, but charge/discharge cycle characteristics deteriorate due to structural degradation
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains high-Ni lithium transition metal oxide for high energy density, while the outer shell contains low-Ni lithium transition metal oxide that provides structural stability. This spatial differentiation of composition allows each region to perform its specialized function: the core delivers high capacity while the shell protects against structural degradation during cycling.
Solution Approach 2:
The patent employs composite materials by combining two different lithium transition metal oxide phases with distinct Ni contents into a single electrode material system. The composite structure integrates the high-capacity characteristics of high-Ni oxide with the structural robustness of low-Ni oxide, achieving synergistic effects that resolve the contradiction between energy density and cycle stability.
2Quantity of substance
If high Ni content is used in lithium transition metal oxide, then battery capacity is increased, but structural stability deteriorates during repeated charge/discharge
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains high-Ni lithium transition metal oxide for high energy density, while the outer shell contains low-Ni lithium transition metal oxide that provides structural stability. This spatial differentiation of composition allows each region to perform its specialized function: the core delivers high capacity while the shell protects against structural degradation.
Solution Approach 2:
The patent applies beforehand cushioning by pre-forming a protective outer shell of low-Ni lithium transition metal oxide around the high-Ni core before electrode assembly. This shell acts as a preemptive protective layer that cushiones the inner high-Ni structure against mechanical stress and structural collapse during subsequent charge/discharge cycling, preventing degradation before it occurs.
3Use of energy by moving object
If more Li is extracted upon charge to increase capacity, then battery energy density is improved, but structural deformation increases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains high-Ni lithium transition metal oxide for high energy density, while the outer shell contains low-Ni lithium transition metal oxide that provides structural stability. This spatial differentiation of composition allows each region to perform its specialized function: the core delivers high capacity while the shell protects against structural degradation.
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 proposed solution enhances the charge/discharge cycle characteristics by inhibiting structural collapse and secondary reactions, resulting in improved battery capacity retention.
Implementation Method 1
substitution of a part of Li with other metal elements in the Li layer specifically improves charge/discharge cycle characteristics
Implementation Method 2
forming a protective film on the negative electrode surface
Implementation Method 3
optimizing the composition and calcination process to maintain structural integrity
Data Source
Figure 1
AI summary
In this non-aqueous electrolyte secondary battery: a positive electrode active material contains a lithium transition metal oxide that has a layered structure including a Li layer and that contains at least prescribed amounts of Ni, Ca, and Al; the proportion of metal elements, excluding Li, in the Li layer is 0.6-2.0 mol% with respect to the total number of moles of metal elements, excluding Li, contained in the lithium transition metal oxide; a negative electrode active material has a coating containing Ca on the surface thereof; and the contained amount of Ca in the coating is not less than 15 mass ppm but less than 80 mass ppm with respect to the total mass of the positive electrode material.