Boron Oxide-Coated Quaternary Cathodes for Stable Li-Ion Cycling
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Solution Overview
Problem
High-nickel quaternary cathode electrode materials in lithium-ion batteries suffer from poor cycle stability due to uneven boron oxide coatings caused by dehydration during the mixing process with boric acid, leading to increased contact area with the electrolyte and subsequent side reactions.
Innovation Solution
A boron oxide-coated quaternary cathode electrode material is developed using metaboric acid or pyroboric acid, which releases less water than boric acid, allowing for uniform oxidative sintering and reducing the contact area with the electrolyte, thereby improving cycle stability through a two-stage low-temperature sintering process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If boric acid is used as a low-temperature coating agent, then coating temperature can be reduced to avoid lithium precipitation, but dehydration occurs during high-speed mixing causing uneven coating
Solution Approach 1:
The patent changes the chemical composition parameter of the coating agent from boric acid to metaboric acid or pyroboric acid. These alternative compounds have lower water content compared to boric acid, which eliminates the dehydration issue during high-speed mixing while still enabling low-temperature coating below 900°C to prevent lithium precipitation.
2Loss of substance
If water washing is used to remove residual alkali, then residual alkali is reduced, but lithium residue is removed creating concentration difference that promotes delithiation reaction
Solution Approach 1:
The patent extracts and removes the water washing step from the processing sequence. By eliminating water washing, the patent prevents the creation of lithium concentration differences that would promote delithiation reactions and subsequent Ni3+/Ni2+ transformation, thereby maintaining cycle stability while still achieving low residual alkali through alternative drying methods.
Solution Approach 2:
The patent performs preliminary alkali removal through controlled drying processes before the material is assembled into batteries. This preliminary action prevents the need for subsequent water washing that would create harmful lithium concentration gradients, addressing the problem proactively rather than reactively.
3Productivity
If high-speed mixing is used to mix boric acid and cathode electrode material, then mixing efficiency is improved, but temperature increase causes dehydration and uneven coating
Solution Approach 1:
The patent changes the physical-chemical parameters of the coating agent by substituting boric acid with metaboric acid or pyroboric acid. These substitutes have inherently lower water content, which prevents dehydration-induced viscosity increase during high-speed mixing, thereby maintaining both high mixing efficiency and uniform coating distribution.
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 boron oxide coating reduces side reactions and enhances the cycle stability of the cathode electrode material, improving electrical performance and reducing energy consumption while maintaining a uniform and complete coating layer.
Implementation Method 1
performing first oxidative sintering on a mixture including a quaternary cathode electrode material matrix and a boron source, to obtain the boron oxide-coated quaternary cathode electrode material
Implementation Method 2
the sintering temperature of the above first oxidative sintering is 150-350° C., and the time is 4-12 h
Implementation Method 3
a boron oxide coating layer, the boron oxide coating layer is arranged on the surface of the quaternary cathode electrode material matrix
Data Source
AI summary
The present disclosure provides a boron oxide-coated quaternary cathode electrode material and a preparation method and application thereof. The boron oxide-coated quaternary cathode electrode material includes a quaternary cathode electrode material matrix and a boron oxide coating layer, the boron oxide coating layer is arranged on the surface of the quaternary cathode electrode material matrix, and the quaternary cathode electrode material matrix, is LiaNixCoyMnzAl(1-x-y-z)O2, herein a=1-1.06, x=0.8-0.9, y=0.01-0.1, and z=0.01-0.1. By having the uniform and complete boron oxide coating layer on the surface of the quaternary cathode electrode material matrix, the above coating layer is a B2O3 coating layer, which may effectively reduce a contact area between the quaternary cathode electrode material matrix in the boron oxide-coated quaternary cathode electrode material and an electrolyte, thereby side reactions on the surface of the quaternary cathode electrode material are reduced in the charging and discharging process, and the cycle stability of the cathode electrode material is improved.