Double-Layer Cathode Coating to Suppress Battery Side Reactions
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Solution Overview
Problem
Conventional secondary batteries experience side reactions such as transition metal dissolution and electrolyte decomposition, leading to degradation and reduced discharge capacity.
Innovation Solution
A coated active material with a halogen-containing layer and a phosphorus-containing layer is applied to the surface of the positive electrode active material, where the halogen-containing layer is positioned between the surface of the particle and the phosphorus-containing layer, comprising a halide and a phosphate compound respectively, to hinder direct contact with the electrolyte and suppress side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is applied to suppress side reactions, then reliability is improved, but device complexity increases
Solution Approach 1:
The coating is divided into two distinct layers: a halogen-containing layer in direct contact with the positive electrode active material particle surface, and a phosphorus-containing layer coating the halogen-containing layer. This segmentation allows each layer to perform its specific function - the halogen layer provides initial protection and the phosphorus layer enhances stability - thereby improving reliability while keeping the structure manageable through clear functional division.
Solution Approach 2:
The invention uses a composite coating structure combining two different materials (halogen-containing compound and phosphorus-containing compound) with complementary properties. The halogen-containing layer offers immediate protection against side reactions, while the phosphorus-containing layer provides enhanced chemical stability. This composite approach achieves superior reliability compared to single-layer coatings without excessive complexity.
2Reliability
If a double-layer coating is applied, then suppression of side reactions is improved, but manufacturing complexity increases
Solution Approach 1:
The halogen-containing layer is formed first as a preliminary step, creating a stable base layer that directly contacts the positive electrode active material. Subsequently, the phosphorus-containing layer is applied over this established base. This preliminary action ensures proper layer formation sequence and adhesion, improving the effectiveness of nickel dissolution suppression while maintaining a systematic and manageable manufacturing process.
Solution Approach 2:
Each layer is designed with specific local quality - the halogen-containing layer has properties optimized for direct contact with the active material surface, while the phosphorus-containing layer has properties optimized for chemical stability and protection. This local quality differentiation allows each layer to be manufactured with targeted characteristics, improving overall suppression effectiveness without requiring complex integrated manufacturing processes.
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 configuration effectively suppresses side reactions while maintaining sufficient discharge capacity of the battery, particularly effective in reducing nickel dissolution from lithium nickel oxide-based electrodes.
Implementation Method 1
a halogen-containing layer that coats at least a portion of a surface of a particle of the positive electrode active material, and a phosphorus-containing layer that coats at least a portion of a surface of the halogen-containing layer
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A coated active material 10 according to the present disclosure includes: a positive electrode active material; a halogen-containing layer 12 coating at least a portion of a surface of a particle 11 of the positive electrode active material; and a phosphorus-containing layer 13 coating at least a portion of the surface of the halogen-containing layer 12. The halogen-containing layer 12 is positioned between the surface of the particle 11 and the phosphorus-containing layer 13. The halogen-containing layer 12 includes a halide and is in contact with the surface of the particle 11. The phosphorus-containing layer 13 includes a phosphate compound.