Composite Cathode Coating for High-Density Lithium Batteries
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Solution Overview
Problem
Existing positive electrodes in lithium batteries suffer from a trade-off between improving cycle characteristics and maintaining high mixing density, leading to deteriorated energy density due to the inclusion of carbonaceous conductive agents.
Innovation Solution
A positive electrode with a composite positive active material having a core of lithium transition metal oxide coated with a shell of metal oxide and carbonaceous material, where the carbonaceous conductive agent is integrated into the shell, enhancing mixture density and preventing agglomeration, while the shell reduces side reactions and internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a carbonaceous conductive agent is added to improve cycle characteristics, then cycle characteristics are improved, but mixing density deteriorates
Solution Approach 1:
The patent merges the functions of the conductive agent and the coating layer by incorporating carbonaceous material into the coating layer structure. This integration allows the coating layer to simultaneously provide protective functions and conductive functions, eliminating the need for separate carbonaceous conductive agents and thereby maintaining high mixing density while improving cycle characteristics.
Solution Approach 2:
The coating layer is designed to perform multiple functions: protecting the positive active material from side reactions, providing conductive pathways through incorporated carbonaceous material, and preventing agglomeration. This multi-functionality resolves the contradiction by making the coating layer responsible for both protection and conduction, eliminating the need for additional conductive agents that would reduce mixing density.
2Reliability
If a carbonaceous conductive agent is added to improve cycle characteristics, then cycle characteristics are improved, but energy density deteriorates
Solution Approach 1:
The patent combines the conductive function with the coating layer by incorporating carbonaceous material into it. This merging eliminates the need for separate conductive agents, thereby maintaining higher mixing density and energy density while still providing the necessary conductive pathways for improved cycle characteristics.
Solution Approach 2:
The patent changes the structural parameters of the coating layer by incorporating carbonaceous material, transforming it from a purely protective layer to a multi-functional layer that also provides conduction. This parameter change allows the system to achieve improved cycle characteristics without the penalty of reduced energy density that would result from adding separate conductive agents.
3Use of energy by moving object
If mixing density is increased to improve energy density, then energy density is improved, but cycle characteristics deteriorate
Solution Approach 1:
The patent merges the protective and conductive functions into the coating layer by incorporating carbonaceous material. This integration allows the system to maintain high mixing density for improved energy density while the coating layer simultaneously provides the conductive pathways necessary for good cycle characteristics.
Solution Approach 2:
The coating layer is designed as a composite material containing both the metal oxide or metal hydroxide and carbonaceous material. This composite structure provides both the protective properties of the metal oxide/hydroxide and the conductive properties of the carbonaceous material, resolving the contradiction between energy density and cycle characteristics.
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 solution results in improved energy density and cycle characteristics of lithium batteries by preventing agglomeration and reducing side reactions, maintaining high mixture density without separate carbonaceous conductive agents.
Implementation Method 1
the carbonaceous conductive agent is integrated into the shell, enhancing mixture density and preventing agglomeration
Implementation Method 2
the shell reduces side reactions and internal resistance
Implementation Method 3
the shell reduces side reactions and internal resistance
Data Source
AI summary
A positive electrode, a lithium battery including the positive electrode, and a method of manufacturing the positive electrode are disclosed. The positive electrode includes: a composite positive active material and a binder. The composite positive active material includes: a core including a lithium transition metal oxide; and a shell on and conformed to a surface of the core. The shell includes: at least one first metal oxide represented by Formula MaOb; and a carbonaceous material. The at least one first metal oxide may be in a carbonaceous material matrix, and M is at least one metal selected from Groups 2 to 13 and 15 and 16. The positive active material layer includes a carbonaceous conductive agent, and the carbonaceous conductive agent is present only in the shell.