Double-Coated High-Nickel Cathode Material for Low Residual Alkali
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Solution Overview
Problem
High-nickel positive electrode materials in lithium-ion batteries suffer from poor cycle performance and safety issues due to high residual alkali content on the surface, which leads to gas production, battery deformation, and potential safety hazards.
Innovation Solution
A double-layer coating is applied to the high-nickel positive electrode material, comprising a lithium cobaltate first coating layer and a transition metal oxide second coating layer, to reduce surface alkali content and specific surface area, improving thermal stability and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-nickel positive electrode material is used to increase capacity and reduce cost, then energy density is improved, but residual alkali content on the surface increases causing poor cycle performance and safety issues
Solution Approach 1:
The coating is divided into two distinct layers: a first coating layer containing lithium cobaltate and a second coating layer containing transition metal oxide. This segmented structure allows each layer to perform specific functions - the first layer addresses residual alkali while the second layer enhances structural stability - thereby resolving the contradiction between high energy density and reliable cycle performance
Solution Approach 2:
The patent uses composite coating materials combining lithium cobaltate with transition metal oxides (such as ruthenium oxide, rhodium oxide, or iridium oxide) in a layered structure. This composite approach leverages the complementary properties of different materials to simultaneously reduce residual alkali content and improve cycle stability, enabling high-nickel materials to achieve both high energy density and reliable performance
2Ease of manufacture
If high-nickel positive electrode material is used to reduce cost, then manufacturing cost is improved, but residual alkali content increases causing gas production and safety hazards
Solution Approach 1:
The double-layer coating structure effectively extracts and removes residual alkali substances from the surface of high-nickel positive electrode material. The first coating layer containing lithium cobaltate specifically targets and eliminates residual lithium oxide, while the second coating layer further purifies the surface, thereby eliminating the source of gas production during charge-discharge cycles
Solution Approach 2:
The patent converts the harmful effect of residual alkali (which causes gas production and safety issues) into a beneficial outcome by using the coating layers to selectively remove these impurities. The residual alkali that would normally cause harm is instead captured and neutralized by the coating structure, transforming a manufacturing disadvantage into an opportunity for improved safety and performance
3Quantity of substance
If single-layer coating is applied to reduce residual alkali, then alkali content is reduced, but electrochemical performance remains unsatisfactory
Solution Approach 1:
The coating is segmented into two functional layers with distinct compositions and roles. The first layer (lithium cobaltate) focuses on reducing residual alkali, while the second layer (transition metal oxide) focuses on enhancing structural stability and electrochemical performance. This segmentation allows optimization of each layer's function, achieving both alkali reduction and satisfactory electrochemical performance
Solution Approach 2:
Different regions of the coating have different compositions and properties tailored to local requirements. The first coating layer has properties optimized for alkali removal, while the second coating layer has properties optimized for structural stability and electrochemical activity. This local quality differentiation enables the coating as a whole to achieve multiple objectives that a single uniform layer cannot accomplish
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 double-layer coating significantly reduces residual alkali content, enhances thermal stability, and improves structural stability and electrochemical performance, addressing the safety and cycle life issues of high-nickel positive electrode materials.
Implementation Method 1
the first coating layer contains lithium cobaltate... significantly reduces residual alkali content
Implementation Method 2
the second coating layer contains an oxide of a transition metal... enhances thermal stability
Implementation Method 3
A double-layer coating is applied to the high-nickel positive electrode material... improves structural stability
Data Source
AI summary
Provided in the present disclosure are a positive electrode material used for a lithium ion battery. The positive electrode material comprises substrate particles, a first coating layer that covers the substrate particles, and a second coating layer that covers the first coating layer; the substrate particles contain LiNixMny CozM1-x-y-zO2; the first cladding layer contains lithium cobalt oxide; and the second coating layer contains an oxide of a transition metal.