Cathode Coating Layer Prevents Transition Metal Diffusion
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Solution Overview
Problem
The reactivity between the solid electrolyte and cathode active material in all-solid state batteries leads to increased interface resistance and material deterioration due to diffusion of transition metal cations during charging and discharging, and existing coating methods face challenges in achieving uniformity and nano-sized coating layers.
Innovation Solution
A cathode material with a coating layer made of compounds like Li(Nb0.6Ta0.4)O3 or Li(Nb0.8Ta0.2)O3, formed using an alcohol-based method involving spray-drying and heat-treatment, is developed to prevent transition metal cation diffusion, with a thickness of 1 nm to 100 nm and content of 0.125 wt% to 0.25 wt%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is formed to prevent diffusion of transition metal cations, then interface resistance is reduced and material stability is improved, but the coating process becomes more complex and costly
Solution Approach 1:
The invention changes the chemical composition parameters of the coating layer by incorporating multiple transition metal elements (M1, M2, M3) with specific atomic ratios. This compositional optimization achieves effective diffusion barrier properties while maintaining process simplicity through direct coating methods without requiring complex multi-step procedures
Solution Approach 2:
The invention uses composite coating materials comprising multiple transition metal oxides or hydroxides (such as Nb, Ta, V combinations) that work synergistically to prevent cation diffusion. This composite approach enhances protective performance while allowing flexible adjustment of coating formulation to balance effectiveness with manufacturing simplicity
2Manufacturing precision
If a nano-sized coating layer is formed to prevent diffusion, then coating uniformity is improved and interface resistance is reduced, but the manufacturing process becomes more difficult
Solution Approach 1:
The invention applies a thin coating layer with controlled thickness (1-100 nm) that provides sufficient protective function without requiring excessive coating material or complex deposition techniques. This partial action approach achieves the necessary diffusion barrier with a simple coating process, avoiding the need for sophisticated nano-scale deposition equipment
Solution Approach 2:
The coating process utilizes self-assembly or spontaneous formation mechanisms where the coating material naturally forms a uniform layer on the cathode active material surface during simple deposition and heat treatment. This self-organizing behavior achieves nano-scale uniformity without requiring complex external control mechanisms
3Productivity
If transition metal cations diffuse between solid electrolyte and cathode active material, then the battery can be charged and discharged, but interface resistance increases and material deteriorates
Solution Approach 1:
The invention introduces a coating layer as an intermediary between the solid electrolyte and cathode active material. This intermediate layer selectively permits lithium ion transport while blocking transition metal cation diffusion, thereby maintaining charge/discharge functionality while preventing harmful material deterioration and interface resistance increase
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
This solution effectively reduces interface resistance, improves charge/discharge performance, and enhances productivity and price competitiveness by forming a uniform nano-sized coating layer without the need for complex chelating agents.
Implementation Method 1
a coating layer that is formed on the cathode active material and made of a compound represented by Chemical Formula 1: Li(M1xM21-x)O3... capable of preventing diffusion of transition metal cations between a cathode active material and a solid electrolyte
Implementation Method 2
a method for preparing the same... involving spray-drying and heat-treatment
Implementation Method 3
obtaining a coating powder by spray-drying the precursor solution; and obtaining the cathode material by heat-treating the coating powder
Data Source
AI summary
A cathode material may include a coating layer capable of preventing transition metal cations from being diffused between a cathode active material and a solid electrolyte when an all-solid state battery is charged and discharged, and a method for preparing the same.