Core-Shell LiNiCoMnO2 Active Material for Battery Thermal Stability
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Solution Overview
Problem
Lithium-containing composite oxides used in non-aqueous secondary batteries have low initial charge/discharge efficiency, leading to decreased capacity and poor charge/discharge cycle and storage characteristics, and they also face challenges in achieving both high capacity and thermal stability.
Innovation Solution
A lithium-containing composite oxide electrode active material with a specific compositional formula (Li1+xMO2) is developed, where x is between -0.15 and 0.15, and M includes Ni, Co, and Mn, with controlled valences and ratios, and a production method involving washing and heat treatment in an oxygen-rich atmosphere to enhance thermal stability and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-containing composite oxides with high Ni content are used to achieve high capacity, then capacity increases, but thermal stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the particle interior maintains high Ni content (0.5-0.8) for high capacity, while the surface layer (5-20 nm thick) contains Mn-rich composition for thermal stability. This spatial differentiation of composition allows simultaneous optimization of capacity and thermal stability that cannot be achieved with uniform composition.
Solution Approach 2:
The patent uses composite materials by combining multiple metal elements (Ni, Co, Mn, and optionally Al, Ti, etc.) in a core-shell architecture. The core region uses LiNi1-x-yCoxMnyO2 with high Ni for capacity, while the surface layer uses LiNi1-a-bCoaMnbO2 with higher Mn content for stability, creating a composite structure that integrates the advantages of different material compositions.
2Stability of the object's composition
If conventional lithium-containing composite oxides are used, then thermal stability can be achieved, but initial charge/discharge efficiency deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the particle interior maintains high Ni content (0.5-0.8) for high capacity, while the surface layer (5-20 nm thick) contains Mn-rich composition for thermal stability. This spatial differentiation of composition allows simultaneous optimization of capacity and thermal stability that cannot be achieved with uniform composition.
3Stability of the object's composition
If lithium-containing composite oxides are used, then thermal stability can be achieved, but charge/discharge cycle characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the particle interior maintains high Ni content (0.5-0.8) for high capacity, while the surface layer (5-20 nm thick) contains Mn-rich composition for thermal stability. This spatial differentiation of composition allows simultaneous optimization of capacity and thermal stability that cannot be achieved with uniform composition.
4Stability of the object's composition
If lithium-containing composite oxides are used, then thermal stability can be achieved, but storage characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the particle interior maintains high Ni content (0.5-0.8) for high capacity, while the surface layer (5-20 nm thick) contains Mn-rich composition for thermal stability. This spatial differentiation of composition allows simultaneous optimization of capacity and thermal stability that cannot be achieved with uniform composition.
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 results in a non-aqueous secondary battery with improved high capacity, thermal stability, and excellent charge/discharge cycle and storage characteristics, ensuring safety even in high temperature environments.
Implementation Method 1
heat treating the washed composite oxide in an oxygen-containing atmosphere
Implementation Method 2
heat treating the washed composite oxide in an oxygen-containing atmosphere to control the valence of Ni and Co
Data Source
AI summary
An electrode active material includes particles of a lithium-containing composite oxide represented by the general compositional formula: Li1+xMO2, where −0.15≦x≦0.15, and M represents an element group of three or more elements including at least Ni, Co and Mn, wherein the ratios of Ni, Co and Mn to the total elements constituting M satisfy 45≦a≦90, 5≦b≦30, 5≦c≦30 and 10≦b+c≦55, where the ratios of Ni, Co and Mn are represented by a, b and c, respectively, in units of mol %, the average valence A of Ni in the whole particles is 2.2 to 3.2, the valence B of Ni on the surface of the particles has the relationship: B<A, the average valence C of Co in the whole particles is 2.5 to 3.2, the valence D of Co on the surface of the particles has the relationship: D<C, and the average valence of Mn in the whole particles is 3.5 to 4.2.