Ni-Rich Cathode Surface Layer for Lower Battery Reaction Resistance
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Solution Overview
Problem
Lithium nickelate-based positive electrode active materials for non-aqueous electrolyte secondary batteries tend to undergo side reactions with the electrolyte, increasing reaction resistance and limiting battery performance.
Innovation Solution
A positive electrode active material comprising a lithium-transition metal composite oxide with a high Ni content, combined with Ca, P, and other elements, and a surface-modifying layer containing Ca and P to reduce reaction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high Ni content is used in lithium nickelate to achieve high energy density, then battery energy density is improved, but side reactions with non-aqueous electrolyte increase causing higher reaction resistance
Solution Approach 1:
A surface-modifying layer containing Ca and P is introduced as an intermediary between the high-Ni positive electrode active material and the non-aqueous electrolyte. This layer acts as a protective barrier that prevents direct contact and harmful side reactions between the electrolyte and the high-Ni material, thereby reducing reaction resistance while preserving the high energy density benefits of the Ni-rich composition.
Solution Approach 2:
The patent employs a composite material structure consisting of a lithium-transition metal composite oxide core (with high Ni content for energy density) combined with a surface-modifying layer containing Ca and P (to reduce reaction resistance). This composite approach allows simultaneous achievement of high energy density and low reaction resistance by combining materials with complementary functions.
2Power
If high Ni content is used in lithium nickelate, then battery output potential is improved, but charge-discharge cycle characteristics deteriorate due to increased reaction resistance
Solution Approach 1:
The surface-modifying layer containing Ca and P serves as a protective intermediary that stabilizes the interface between the high-Ni positive electrode material and the electrolyte during repeated charge-discharge cycles. This reduces reaction resistance accumulation over time, thereby improving charge-discharge cycle characteristics while maintaining high output potential.
Solution Approach 2:
The patent modifies the surface composition parameters of the positive electrode active material by incorporating specific elements (Ca and P) in controlled proportions. This parameter change at the surface level creates a more stable electrochemical interface, reducing degradation during cycling while preserving the high-power characteristics of the Ni-rich bulk material.
Data Source
Figure 1
AI summary
Provided is a positive electrode active material able to reduce reaction resistance. This positive electrode active material, which is included in a non-aqueous electrolyte secondary battery, contains a lithium-transition metal composite oxide. The lithium-transition metal composite oxide contains prescribed amounts of Ni, Ca, P, and Me (Me being at least one element selected from the group consisting of B, Al, Si, Ti, Mn, Fe, Co, Sr, Zr, Nb, Mo, Sn, W, and Bi). The lithium-transition metal composite oxide contains secondary particles formed by agglomeration of primary particles. On the surfaces of the primary particles, including the surfaces of the secondary particles, there is a surface modification layer containing Ca and P.