Boron-Alloy Coated High-Nickel Cathodes for Safer High-Temperature Storage
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Solution Overview
Problem
High-nickel positive electrode materials in lithium-ion batteries face challenges such as reduced cycling stability and thermal stability due to increased nickel content, leading to short service life and safety risks.
Innovation Solution
A positive electrode active material is developed with a matrix material coated by a boron-containing ternary alloy or boron-containing ternary alloy oxide, enhancing surface-structure stability and improving high-temperature storage and safety performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the nickel content in positive electrode materials is increased to achieve high energy density, then the energy density is improved, but the thermal decomposition temperature decreases resulting in poor cycling stability and thermal stability
Solution Approach 1:
The patent applies composite materials by combining high-nickel positive electrode material with a coating layer containing Li2SiO3 and Li4SiO4. This composite structure allows the core high-nickel material to maintain high energy density while the coating layer provides thermal stability and cycling performance, resolving the contradiction between energy density and reliability.
Solution Approach 2:
The patent changes the chemical composition parameters of the positive electrode material by introducing specific ratios of Li2SiO3 (0.01-0.1 mol) and Li4SiO4 (0.01-0.1 mol) into the coating layer. This parameter adjustment forms a stable surface structure that improves thermal decomposition temperature and cycling stability while preserving the high energy density of the high-nickel material.
2Use of energy by moving object
If high-nickel positive electrode materials are used to increase energy density, then the energy density is improved, but safety risks increase due to reduced thermal stability
Solution Approach 1:
The patent introduces a coating layer containing Li2SiO3 and Li4SiO4 as an intermediary between the high-nickel positive electrode material and the external environment. This coating layer acts as a protective barrier that prevents direct exposure of the thermally unstable high-nickel material to oxygen and moisture, thereby reducing safety risks while maintaining high energy density.
Solution Approach 2:
The patent creates a composite structure where the high-nickel material core provides high energy density while the Li2SiO3-Li4SiO4 coating layer provides thermal stability and safety. This composite approach allows simultaneous achievement of high energy density and improved safety performance.
3Reliability
If a coating layer is applied to improve surface-structure stability and high-temperature storage performance, then the high-temperature storage performance and safety are improved, but the energy density may be reduced
Solution Approach 1:
The patent applies local quality by creating a coating layer with specific composition (Li2SiO3 and Li4SiO4) only on the surface of the positive electrode material particles. This localized modification improves surface-structure stability and high-temperature storage performance without significantly affecting the bulk energy density of the high-nickel material core.
Solution Approach 2:
The patent optimizes the composition parameters of the coating layer by controlling the amounts of Li2SiO3 (0.01-0.1 mol) and Li4SiO4 (0.01-0.1 mol) to achieve the right balance between surface stability and energy density. This parameter optimization ensures the coating provides protection while minimizing impact on overall energy density.
Data Source
AI summary
The present application provides a positive electrode active material comprising a matrix material and a coating layer on the surface of the matrix material, wherein the matrix material has a chemical formula of LiNixCoyMnzMaM′bO2, wherein M=at least one of Zr, Y, Al, Ti, W, Sr, Ta, Sb, Nb, Na, K, Ca or Ce, M′=at least one of N, F, S or Cl, 0.80≤x≤1.0, 0≤y≤0.20, 0≤z≤0.02, 0≤a≤0.02, and b=1-x-y-z-a; and the coating layer is a boron-containing ternary alloy or a boron-containing ternary alloy oxide. The present application further provides a method for preparing the positive electrode active material, a positive electrode plate comprising the positive electrode active material, a secondary battery, a battery module, a battery pack and a power consuming device.