Layered Cathode Composition for Thermal-Stable Li-Ion Cycling
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges with thermal stability and cycle performance due to changes in the crystal structure of positive electrode materials, particularly those with a layered rock salt structure, leading to reduced battery capacity and safety concerns like thermorunaway.
Innovation Solution
Development of positive electrode active material particles with a layered lithium-composite oxide structure, specifically (LiγXe)(NiaCObXcZd)O2, where X is a divalent metallic element substituting for Li-site, and Z includes Al and/or Mn, with controlled composition and calcination processes to enhance thermal stability and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If positive electrode materials with layered rock salt structure are used to achieve high charge/discharge capacity and high battery voltage, then battery capacity and voltage are improved, but thermal stability deteriorates and thermorunaway occurs at lower temperatures
Solution Approach 1:
The patent modifies the compositional parameters of the layered rock salt structure by controlling the ratio of Ni to other metal elements (Co, Mn, Al, Mg, Zn, Ca, Sr, Ba, Pb, Fe, Mo, W) within specific ranges (Ni: 0.8-0.95, Co: 0.02-0.1, Mn: 0.01-0.05, Al: 0.01-0.05, Mg: 0.01-0.05). This parameter optimization maintains high battery capacity while improving thermal stability by preventing oxygen release at lower temperatures.
Solution Approach 2:
The patent creates a composite positive electrode material by combining multiple metal elements (Ni, Co, Mn, Al, Mg, and other stabilizing elements) in a layered rock salt structure. This composite approach leverages the high capacity of Ni while using Co, Mn, Al, and Mg to stabilize the crystal structure and prevent thermorunaway, achieving both high performance and safety.
2Reliability
If positive electrode materials undergo repeated charge/discharge cycles or storage at high temperature, then battery capacity is gradually reduced due to crystal structure change and expansion/contraction, but using more stable materials reduces capacity
Solution Approach 1:
The patent optimizes the compositional parameters within the layered rock salt structure by precisely controlling the content of each metal element. The specific composition range (Ni: 0.8-0.95, Co: 0.02-0.1, Mn: 0.01-0.05, Al: 0.01-0.05, Mg: 0.01-0.05) balances structural stability during cycling with high battery capacity, preventing excessive expansion/contraction while maintaining electrochemical activity.
Solution Approach 2:
The patent incorporates stabilizing metal elements (Co, Mn, Al, Mg) in advance into the layered rock salt structure to prevent crystal structure degradation before it occurs. These elements act as structural buffers that accommodate volume changes during charge/discharge cycles and prevent phase transitions at high temperatures, thereby maintaining both stability and capacity.
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 provides excellent thermal stability, maintaining sufficient battery capacity and reducing resistance increase, suitable for non-aqueous electrolyte secondary batteries, while ensuring safety by stabilizing the crystal structure and reducing oxygen desorption at high temperatures.
Implementation Method 1
X is a divalent metallic element capable of substituting for Li-site
Implementation Method 2
maintaining a sufficient battery capacity; methods for producing the same; and non-aqueous electrolyte secondary batteries with excellent thermal stability in addition to excellent structural stability
Implementation Method 3
the materials release oxygen with structure thereof being damaged to react with an electrolytic solution at a lower temperature
Implementation Method 4
the materials release oxygen with structure thereof being damaged to react with an electrolytic solution at a lower temperature
Data Source
AI summary
Excellent thermal stability in addition to excellent cycle property with maintaining a sufficient battery capacity is shown by positive electrode active material particles having a layered rock salt structure, represented by the compositional formula: (LiγXe)(NiaCobXcZd)O2, in the compositional formula: X is a divalent metallic element capable of substituting for Li-site; Z is a metallic element containing at least Al and/or Mn, other than X; 0.93≤γ≤1.15; 0.82≤a<1.00; 0≤b≤0.12; 0.001≤c+e≤0.040; 0≤d≤0.10; and a+b+c+d=1.