Coated Cathode Active Material for Ni-Rich Surface Stability
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Solution Overview
Problem
Lithium ion batteries, particularly those with Ni-rich electrode active materials, face issues with undesired reactions on the electrode surface, leading to electrolyte decomposition and hindered lithium exchange during charging and discharging, which existing coatings and washing methods have not adequately addressed to improve electrochemical properties.
Innovation Solution
A process involving particulate electrode active materials treated with aqueous solutions or slurries of Al, Sb, or heteropoly acids, followed by filtration and thermal treatment, to deposit elements like Al, Sb, B, Mo, W, Si, and P on the surface, enhancing the electrochemical properties of Ni-rich materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Ni-rich electrode active materials are used to increase capacity, then energy density is improved, but surface reactions cause electrolyte decomposition and hinder lithium exchange
Solution Approach 1:
A coating layer comprising at least one element selected from Al, Sb, B, Mo, W, Si, and P is applied to the surface of the Ni-rich electrode active material. This coating acts as an intermediary barrier that prevents direct contact between the reactive Ni-rich material and the electrolyte, thereby eliminating surface reactions and electrolyte decomposition while preserving the high capacity benefits of Ni-rich materials
Solution Approach 2:
The invention applies a protective coating specifically to the surface region of the electrode active material particles. This local modification preserves the bulk properties of the Ni-rich material (high capacity) while altering only the surface properties to reduce reactivity with the electrolyte, allowing lithium exchange to proceed without harmful side reactions
2Reliability
If conventional coating methods are applied to protect the surface, then surface protection is improved, but lithium exchange during charging and discharging is hindered
Solution Approach 1:
The coating layer is designed with specific compositional parameters (elements from Al, Sb, B, Mo, W, Si, P) and controlled thickness (0.1-10 nm) to achieve optimal balance between protection and lithium ion conductivity. These parameter optimizations ensure the coating provides surface protection while maintaining efficient lithium exchange kinetics
Solution Approach 2:
The coating layer is formed as a composite structure containing multiple elements (at least one from Al, Sb, B, Mo, W, Si, and P) that work synergistically to provide both protective and conductive functions. This composite approach allows the coating to simultaneously protect against electrolyte decomposition and facilitate lithium ion transport
3Manufacturing precision
If washing with water is performed to remove free LiOH or Li2CO3, then surface cleanliness is improved, but electrochemical properties do not improve and may deteriorate
Solution Approach 1:
Instead of relying on washing to remove surface contaminants, the invention applies a protective coating layer that acts as an intermediary barrier. This coating prevents harmful surface reactions and electrolyte decomposition regardless of residual LiOH or Li2CO3, providing more reliable electrochemical performance than washing alone
Solution Approach 2:
The coating application is performed as a preliminary protective measure before battery assembly, creating a stable surface layer that prevents subsequent electrolyte decomposition. This preliminary action ensures consistent electrochemical performance without requiring perfect surface cleanliness achieved through extensive washing
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 process results in electrode active materials with improved cycling stability, reduced gassing, and minimized electrolyte decomposition, as evidenced by enhanced electrochemical performance and surface modification.
Implementation Method 1
treating said particulate electrode active material with an aqueous solution or slurry of at least one compound of Al, Sb, or B, or of at least one heteropoly acid or of its respective ammonium or lithium salt or salt of Al, Ga, In, or Ba, thereby depositing at least one element selected from Al, Sb, B, Mo, W, Si and P on the surface of said particulate electrode active material
Implementation Method 2
treating said particulate electrode active material with an aqueous solution or slurry of at least one compound of Al, Sb, or B, or of at least one heteropoly acid or of its respective ammonium or lithium salt or salt of Al, Ga, In, or Ba, thereby depositing at least one element selected from Al, Sb, B, Mo, W, Si and P on the surface of said particulate electrode active material
Implementation Method 3
treating the residue obtained from step (d) thermally
Data Source
AI summary
Disclosed herein is a process for manufacturing a coated cathode active material. The process includes (a) providing a particulate electrode active material according to general formula Li1+xTM1−xO2, where TM includes Ni and optionally Co and/or Mn, optionally Al, Mg, and/or Ba, and transition metals other than Ni, Co, and Mn, and where x is between zero and 0.2, (b) treating said particulate electrode active material with an aqueous solution or slurry such that at least one element selected from Al, Sb, B, Mo, W, Si and P is deposited on the surface of said particulate electrode active material, (c) removing the water by filtration, (d) adding an aqueous solution of a compound of Al, B, or Sb to the solid residue obtained from step (c), thereby depositing Al, B, and/or Sb on the surface of said solid residue, and (e) treating the residue obtained from step (d) thermally.