Amorphous Titanium Oxide Cathode Coating for Electrolyte Stability
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Solution Overview
Problem
High-voltage cathodes in Li-ion batteries face issues with electrolyte decomposition during cycling due to coating instability, which affects battery performance and lifespan, as existing coatings either hinder Li+ ion diffusion or lead to mechanical instability.
Innovation Solution
A coated cathode with a thickness of 1 to 20 nm of amorphous halogen-doped titanium oxide coating, which ensures sufficient Li+ ion diffusion, electrochemical, chemical, and mechanical stability, preventing electrolyte decomposition and maintaining battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating is applied to the cathode to prevent electrolyte decomposition, then battery stability and lifetime are improved, but Li+ ion diffusion through the coating is hindered
Solution Approach 1:
The patent applies amorphous halogen-doped titanium oxide coating with controlled thickness parameters (1-20 nm) and specific composition parameters (halogen doping concentration) to optimize both protective function and ion diffusion capability. The doping concentration and thickness are precisely controlled to balance electrolyte decomposition prevention with Li+ ion transport efficiency.
Solution Approach 2:
The patent uses composite amorphous halogen-doped titanium oxide material that combines the protective properties of titanium oxide with the enhanced ionic conductivity provided by halogen doping. This composite structure allows the coating to simultaneously provide electrochemical stability and facilitate Li+ ion diffusion through the doped lattice structure.
2Reliability
If coating thickness is increased to improve coverage and stability, then electrochemical and chemical stability are improved, but mechanical instability and cracking occur
Solution Approach 1:
The patent controls the coating thickness within a specific range (1-20 nm) and adjusts the halogen doping concentration to optimize the balance between electrochemical stability and mechanical flexibility. The amorphous structure combined with controlled thickness prevents cracking while maintaining protective function.
Solution Approach 2:
The patent employs a thin film coating approach where the amorphous halogen-doped titanium oxide layer is deposited as a flexible thin film (1-20 nm) that can accommodate the expansion and contraction of the cathode material during cycling without cracking or delaminating.
3Speed
If coating thickness is reduced to improve Li+ ion diffusion, then rate performance is improved, but coverage is insufficient and side reactions increase
Solution Approach 1:
The patent optimizes the coating thickness parameter to the range of 1-20 nm, which is thick enough to provide complete coverage and prevent side reactions, yet thin enough to allow sufficient Li+ ion diffusion. The halogen doping concentration is also optimized to enhance ionic conductivity within this thickness range.
Solution Approach 2:
The amorphous halogen-doped titanium oxide composite material provides enhanced ionic conductivity that allows effective Li+ ion diffusion even at coating thicknesses sufficient for complete coverage, unlike conventional coatings that require thinner layers for comparable diffusion rates.
4Use of energy by moving object
If high-voltage cathode is used to increase energy density, then battery energy density is improved, but electrolyte decomposition increases
Solution Approach 1:
The amorphous halogen-doped titanium oxide coating acts as an intermediary protective layer between the high-voltage cathode material and the electrolyte. This intermediate coating prevents direct contact and harmful interactions while allowing beneficial Li+ ion transfer, thereby enabling high-voltage operation without excessive electrolyte decomposition.
Solution Approach 2:
The patent optimizes the coating composition parameters (halogen doping concentration) and thickness to provide effective protection against electrolyte decomposition at high operating voltages (>4V vs. Li+/Li), enabling the cathode to operate at higher potentials with improved stability.
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 coating effectively prevents electrolyte decomposition, enhances cycle-ability, shelf life, and stability of the electrode, while maintaining high discharge voltage capabilities.
Implementation Method 1
the diffusion of Li+ ions through the coating should be sufficiently large to not hinder the rate performance of the battery
Implementation Method 2
the coating has a thickness of from 1 to 20 nm... the coating completely covers the cathode, thereby preventing any physical contact between the active material of the coated electrode and the electrolyte
Data Source
AI summary
A coated cathode, a device including the coated cathode and methods for preparation thereof is provided. The coated cathode includes: an active material (10) for supplying and storing Li+ ions, an electrically conductive additive (12), and a coating (11), different from the active material (10), that coats surfaces of the active material (10), wherein the coating (11) comprises amorphous halogen-doped titanium oxide, and wherein the coating (11) has a thickness ranging from 1 to 20 nm.