Ni-Rich Cathode Interface Doping for Longer Li-Ion Battery Cycling
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, experience a significant decrease in capacity with repeated charge and discharge cycles, and there is a need to improve their charge-discharge cycle characteristics.
Innovation Solution
Incorporating a lithium-transition metal composite oxide with a layered structure containing greater than or equal to 75 mol% Ni and specific elements like Ca and Sr, or W, Mo, Ti, Si, Nb, and Zr, at the interface between primary particles of the positive electrode, and using a silicon-containing material as the negative electrode active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high-capacity positive electrode active material is used, then the battery capacity increases, but the charge-discharge cycle characteristics deteriorate due to increased side reactions
Solution Approach 1:
The patent applies local quality by introducing specific metal elements (Ca, Sr from Group 2; W, Mo, Ti, Si, Nb, Zr from Groups 4-5) at the interface between primary particles within secondary particles of the positive electrode active material. This localized elemental distribution at critical interfaces suppresses side reactions specifically where they occur most, thereby improving charge-discharge cycle characteristics while maintaining high battery capacity
Solution Approach 2:
The patent employs composite materials by combining the positive electrode active material with specific metal elements forming a multi-element composite structure. The composite consists of the base active material supplemented with Group 2 and Group 4-5 metal elements at particle interfaces, creating a composite system that simultaneously achieves high capacity and excellent cycle stability
2Reliability
If the positive electrode active material structure is modified to improve cycle characteristics, then the charge-discharge cycle characteristics improve, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the positive electrode active material into secondary particles composed of aggregated primary particles. The specific metal elements are introduced at the interfaces between these primary particles, creating a segmented structure where each interface acts as an independent functional unit for suppressing side reactions, thereby improving cycle characteristics through modular structural design
Data Source
Figure 1
AI summary
With respect to a nonaqueous electrolyte secondary battery (10) according to one example embodiment of the present invention, a positive electrode (11) contains, as a positive electrode active material, a lithium transition metal composite oxide that has a layered structure and contains not less than 75 mol% of Ni with respect to the total molar quantity of metal elements excluding Li. The lithium transition metal composite oxide is in the form of secondary particles that are obtained by aggregation of primary particles; and at least one element selected from the group consisting of Ca and Sr, and at least one element selected from the group consisting of W, Mo, Ti, Si, Nb and Zr are present at the interfaces between the primary particles inside the secondary particles. A negative electrode (12) contains, as a negative electrode active material, a silicon-containing material.