Ni-Rich Cathode Active Material with Reduced Interlayer Contraction
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Solution Overview
Problem
Lithium-ion batteries face limitations in cycling stability and capacity due to interlayer contraction during charging, particularly in Ni-rich cathode materials, leading to reduced cycle life and capacity loss.
Innovation Solution
A process for manufacturing composite oxides of the formula x·Li2Ni1-y1-y2Mny1M1y2O3·(1−x)·LiNi1-zM2zO2, involving steps such as providing a particulate hydroxide or oxide precursor, adding lithium and optional dopants, and heating in controlled oxygen atmospheres to minimize interlayer contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high Ni content (at least 80 mol-%) is used in cathode materials to achieve high energy density, then specific energy is improved, but cycle life is reduced due to instability problems and interlayer contraction
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core contains high Ni content (≥80 mol-%) for high energy density, while the outer shell contains modified Ni content and dopants (M1, M2) for structural stability. This spatial differentiation allows each region to perform its specialized function: the core provides energy density while the shell provides stability during cycling.
Solution Approach 2:
The patent uses composite materials by combining multiple metal elements (Ni, Mn, M1, M2) in a layered composite oxide structure with formula x·Li2Ni1-y1-y2Mny1M1y2O3·(1−x)·LiNi1-zM2zO2. The composite nature allows synergistic effects where different metals contribute different properties: Ni for capacity, Mn for stability, M1 for structural reinforcement, and M2 for electrochemical performance.
2Ease of manufacture
If conventional single-step calcination at high temperature (600-1000°C) is used to form cathode materials, then manufacturing process is simplified, but interlayer contraction (>4%) and particle cracking occur reducing cycling stability
Solution Approach 1:
The patent segments the single calcination step into two distinct stages: first calcination at 680-800°C to form the base composite oxide structure, followed by a second calcination at 450-580°C after adding additional lithium source to complete the reaction and form the final core-shell structure. This segmentation allows better control over the formation process, preventing excessive interlayer contraction and particle cracking that would occur in a single high-temperature step.
Solution Approach 2:
The patent applies preliminary action by performing the first calcination step to form the composite oxide precursor structure before adding the lithium source and performing the second calcination. This preliminary formation of the core-shell structure with controlled Ni content distribution prevents the formation of unstable phases and minimizes interlayer contraction that would occur if all components were mixed and calcined together in a single step.
3Reliability
If interlayer spacing contraction is minimized to improve cycling stability, then capacity retention is improved, but manufacturing complexity increases due to controlled multi-step process
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition parameters (x, y1, y2, z) and processing parameters (temperature ranges, oxygen atmosphere) to achieve the desired core-shell structure with minimal interlayer contraction. The specific formula x·Li2Ni1-y1-y2Mny1M1y2O3·(1−x)·LiNi1-zM2zO2 with defined parameter ranges allows optimization of both cycling stability and capacity retention while maintaining a systematic manufacturing approach.
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 process results in electrode active materials with reduced interlayer contraction, enhancing cycling stability and capacity retention, thereby improving the longevity and performance of lithium-ion batteries.
Implementation Method 1
During the thermal treatment a solid-state reaction takes place, and the electrode active material is formed
Implementation Method 2
The calcination—or firing—often also referred to as thermal treatment or heat treatment of the precursor—is usually carried out at temperatures in the range of from 600 to 1,000° C.
Implementation Method 3
heating the mixture obtained from step (b) to 680 to 800° C. in an atmosphere containing oxygen
Data Source
AI summary
Process for making a composite oxide according to the formula x·Li2Ni1-y1-y2Mny1M1y2O3·(1−x)·LiNi1-zM2zO2 wherein x is in the range of from 0.01 to 0.5, z is in the range of from zero to 0.5,M1 is selected from Ti, Zr, Sn, Ge, Ta, Nb, Sb, W, and Mo, and combinations of at least two of the foregoing,M2 is at least one of Co, Al, Mg, Fe, or Mn, or a combination of at least two of the foregoing,0.1≤y1≤0.75, zero≤y2≤0.05,said process comprising the following steps:(a) providing a particulate hydroxide, oxide or oxyhydroxide of TM where TM has the general formula x·Ni1-y1-y2Mny1M1y·(1−x)Ni1-zM2z, or the respective species without M1 and/or M2,(b) adding a source of lithium,(c) treating the mixture obtained from step (b) thermally under an atmosphere comprising oxygen in two steps:(c) heating the mixture obtained from step (b) to 680 to 800° C. in an atmosphere containing in the range of from 10 to 100 vol-% oxygen, and,(e) heating the intermediate from step (c) to 450 to 580° C. in an atmosphere containing at least 90 vol-% oxygen.