Li-Ni-Based Composite Oxide Particles with Mn Gradient
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Solution Overview
Problem
Lithium nickel oxide (LiNiO2) based composite oxides used in non-aqueous electrolyte secondary batteries face issues with thermal stability due to Jahn-Teller distortion and reactions with electrolyte solutions, leading to degradation in cycle characteristics and safety concerns.
Innovation Solution
The development of Li-Ni-based composite oxide particles with a surface coating of Li-Mn-based composite oxide, where the concentration of Mn is increased from the center to the surface, and the coating layer is composed of specific metal elements like Co, Al, Fe, Mg, Zr, Ti, and B, enhancing thermal stability and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LiNiO2 is used as the positive electrode active substance to achieve large charge/discharge capacity, then the energy density is improved, but the thermal stability upon charging deteriorates
Solution Approach 1:
The patent uses a core-shell structure where LiNiO2 core particles are coated with a Li-Mn-based composite oxide shell. This composite structure allows the high-capacity LiNiO2 core to maintain its energy density while the stable Li-Mn-based shell provides thermal stability and prevents harmful reactions with the electrolyte, thus resolving the contradiction between high capacity and thermal stability.
Solution Approach 2:
The Li-Mn-based composite oxide coating acts as an intermediary layer between the LiNiO2 active substance and the electrolyte solution. This intermediate shell prevents direct contact and harmful reactions between the electrolyte and the LiNiO2, thereby improving thermal stability while preserving the charge/discharge capacity of the core material.
2Use of energy by moving object
If LiNiO2 is used to achieve high energy density, then the battery performance is improved, but the cycle durability deteriorates due to crystal structure distortion
Solution Approach 1:
The core-shell composite structure with LiNiO2 core and Li-Mn-based shell provides mechanical support and structural stability during charge/discharge cycles. The shell constrains the Jahn-Teller distortion of the Ni3+ ions in the core, preventing crystal structure degradation and maintaining cycle durability while preserving the high energy density of the LiNiO2 core.
3Reliability
If the surface of Li-Ni-based oxide particles is coated with stable elements to improve thermal stability, then the safety is improved, but the reactivity with electrolyte solution may be affected
Solution Approach 1:
The Li-Mn-based composite oxide coating serves as an intermediary protective layer that is thermally stable and chemically inert toward the electrolyte. This intermediate shell prevents direct harmful reactions between the LiNiO2 core and the electrolyte solution, thereby improving both thermal stability and safety without significantly affecting the electrochemical performance.
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 Li-Ni-based composite oxide particles exhibit improved thermal stability and safety, with an exothermic peak temperature shifted to a higher range, maintaining high discharge capacity and reducing reactivity with electrolyte solutions, thus suitable for use as a positive electrode active substance.
Implementation Method 1
it is considered to be effective that the contact surface thereof with the electrolyte solution, i.e., the surface of the respective particles, is coated with other stable elements
Implementation Method 2
the crystal structure of LiNiO2 suffers from Jahn-Teller distortion since Ni3+
Implementation Method 3
the concentration of Mn is increased from a center toward a surface of the respective particles
Implementation Method 4
calcine the particles under the condition which is free from inclusion of Ni2+
Implementation Method 5
allowing an oxide and/or a hydroxide which comprise Mn to mechanically adhere to an Li-Ni-based oxide comprising Co and/or Al; and then heat-treating the obtained material at a temperature of not lower than 400°C and not higher than 1,000°C
Data Source
Figure 1
AI summary
The present invention relates to Li-Ni-based composite oxide particles comprising Mn, and Co and/or Al, wherein Co and Al are uniformly dispersed within the particles, and Mn is present with a gradient of its concentration in a radial direction of the respective particles such that a concentration of Mn on a surface of the respective particles is higher than that at a central portion thereof. The Li-Ni-based composite oxide particles can be produced by allowing an oxide and a hydroxide comprising Mn to mechanically adhere to Li-Ni-based oxide comprising Co and/or Al; and then heat-treating the obtained material at a temperature of not lower than 400°C and not higher than 1,000°C. The Li-Ni-based composite oxide particles of the present invention are improved in thermal stability and alkalinity.