Ni-Rich Cathode Material Coating for Lower DCIR and Cycle Fade
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Solution Overview
Problem
Lithium-containing composite oxides with Ni as a main component in non-aqueous electrolyte secondary batteries suffer from side reactions with the electrolyte, leading to reduced battery capacity and increased direct-current resistance (DCIR), while existing solutions do not effectively address both charge-discharge cycle characteristics and DCIR simultaneously.
Innovation Solution
A positive electrode active material is developed, comprising a lithium-containing composite oxide with a layered rock-salt structure, containing Ni, Ca, and Sr, where the Ca/Sr ratio is greater than or equal to 1, and a sulfonate compound is present on the surfaces of secondary particles or interfaces between primary particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a lithium-containing composite oxide containing Ni as a main component is used, then high energy density is achieved, but side reactions with non-aqueous electrolyte occur easily, reducing battery capacity and increasing direct-current resistance
Solution Approach 1:
A sulfonate compound coating layer is introduced as an intermediary between the lithium-containing composite oxide and the non-aqueous electrolyte. This coating layer prevents direct contact and side reactions between the Ni-based oxide and electrolyte, thereby maintaining battery capacity and reducing DCIR while preserving the high energy density of the Ni-containing material
Solution Approach 2:
The positive electrode active material is designed as a composite structure combining lithium-containing composite oxide with Ni as main component and a sulfonate compound coating layer. This composite material approach allows the inner Ni-based oxide to provide high energy density while the outer sulfonate coating provides chemical stability and prevents harmful side reactions
2Use of energy by moving object
If a lithium-containing composite oxide containing Ni as a main component is used, then high energy density is achieved, but direct-current resistance increases due to side reactions with electrolyte
Solution Approach 1:
The sulfonate compound coating acts as a protective intermediary that reduces direct-current resistance by preventing side reactions between the Ni-based lithium-containing composite oxide and the non-aqueous electrolyte, thereby maintaining efficient charge transfer while preserving high energy density
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 solution improves the charge-discharge cycle characteristics and reduces direct-current resistance (DCIR) in non-aqueous electrolyte secondary batteries, enhancing the overall performance and capacity retention of the batteries.
Implementation Method 1
a sulfonate compound represented by the formula I is present on surfaces of the secondary particles or on interfaces between the primary particles
Data Source
AI summary
This positive electrode active material comprises a lithium-containing composite oxide; the lithium-containing composite oxide contains at least Ni, Ca and Sr; the molar ratio (Ca/Sr ratio) of the content of Ca to the content of Sr is 1 or more; the sum of the content of Ca and the content of Sr in the lithium-containing composite oxide is 0.05% to 1% by mole; the lithium-containing composite oxide contains secondary particles, each of which is formed of aggregated primary particles; and a sulfonic acid compound which is represented by general formula I is present on the surfaces of the secondary particles or on the interfaces between the primary particles. (In the formula, A represents a group 1 element or a group 2 element; R represents a hydrocarbon group; and n is 1 or 2.)