Multi-Phase Cathode Material with Low-Conductivity Coating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cathode active materials for batteries suffer from low cycle characteristics due to electrolyte decomposition and anion desorption at high electric potentials, leading to reduced capacity maintenance after repeated charge-discharge cycles.
Innovation Solution
A cathode active material comprising a lithium composite oxide with a multi-phase mixture of monoclinic, hexagonal, and cubic crystal structures, coated with a covering material of low electronic conductivity, which prevents direct contact with the electrolyte and suppresses side reactions, thereby enhancing cycle stability and capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a cathode active material operates at high electric potential to achieve high capacity, then the battery capacity increases, but electrolyte decomposition and anion desorption occur leading to poor cycle characteristics
Solution Approach 1:
A covering material layer is introduced as an intermediary between the lithium composite oxide and the electrolyte. This covering layer prevents direct contact between the electrolyte and the cathode active material surface, thereby suppressing electrolyte decomposition and anion desorption while allowing the cathode to operate at high electric potential for high capacity
Solution Approach 2:
The cathode active material is constructed as a composite structure consisting of a lithium composite oxide core with a covering material shell. This composite structure combines the high capacity characteristics of the lithium composite oxide at high potential with the protective function of the covering material, achieving both high capacity and good cycle characteristics
2Power
If the covering material has high electronic conductivity to improve electron transport, then electrical performance improves, but side reactions with electrolyte increase reducing cycle stability
Solution Approach 1:
The electronic conductivity of the covering material is optimized to a specific range (10^-10 to 10^6 S/m). This parameter optimization balances electron transport capability for good electrical performance with sufficient electrical resistance to suppress side reactions with the electrolyte, achieving both electrical performance and cycle 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 proposed cathode active material achieves a high capacity maintenance ratio of over 90% after 20 charge-discharge cycles, maintaining battery performance by preventing electrolyte decomposition and anion desorption, and ensuring stability at high electric potentials.
Implementation Method 1
a covering material which covers a surface of the lithium composite oxide
Implementation Method 2
the covering material has an electronic conductivity of not more than 106 S/m
Implementation Method 3
the lithium composite oxide is a multi-phase mixture including: a first phase having a crystal structure which belongs to a monoclinic crystal; a second phase having a crystal structure which belongs to a hexagonal crystal; and a third phase having a crystal structure which belongs to a cubical crystal
Data Source
AI summary
Provided is a cathode active material comprising a lithium composite oxide and a covering material which covers a surface of the lithium composite oxide. The lithium composite oxide is a multi-phase mixture including a first phase having a crystal structure which belongs to a monoclinic crystal; a second phase having a crystal structure which belongs to a hexagonal crystal; and a third phase having a crystal structure which belongs to a cubical crystal. The lithium composite oxide has an integral intensity ratio I(18°-20°)/I(43°-46°) of not less than 0.05 and not more than 0.99, where the integral intensity I(α°-β°) is an integral intensity of a peak which is a maximum peak present within a range of a diffraction angle 2θ of not less than α° and not more than β° in an X-ray diffraction pattern of the lithium composite oxide. The covering material has an electronic conductivity of not more than 106 S/m.