High-Ni Cathode Material With Protective Doping for Battery Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium nickelate-based positive electrode active materials with high Ni content are prone to side reactions with non-aqueous electrolytes, leading to structural instability and self-exothermic reactions that compromise battery safety, particularly at elevated temperatures.
Innovation Solution
A lithium-transition metal composite oxide with specific elemental compositions and structural ratios, including Ni, Mn, P, and optionally Ca/Sr, is used to stabilize the crystal structure and inhibit side reactions, enhancing safety through controlled X-ray diffraction peak ratios and surface modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high Ni content (≥75 mol%) is used in lithium nickelate to achieve high energy density, then energy density is improved, but side reactions with non-aqueous electrolyte increase and structural stability deteriorates
Solution Approach 1:
The patent uses composite materials by forming a coated structure where a lithium nickelate-based positive electrode active material (with high Ni content ≥75 mol% for high energy density) is coated with a protective layer containing Ca, Sr, and P. This composite structure allows the inner high-Ni material to provide high energy density while the outer protective layer prevents side reactions with electrolyte and maintains structural stability during charge-discharge cycles.
2Use of energy by moving object
If high Ni content (≥75 mol%) is used to achieve high energy density, then energy density is improved, but safety deteriorates due to self-exothermic reactions
Solution Approach 1:
The patent introduces an intermediary protective layer containing Ca, Sr, and P that acts as a mediator between the high-Ni positive electrode active material and the non-aqueous electrolyte. This intermediary layer prevents direct contact and harmful self-exothermic reactions between the high-Ni material and electrolyte, thereby improving safety while allowing the high-Ni material to maintain its high energy density properties.
3Quantity of substance
If Li is abstracted during charge to increase capacity, then capacity is improved, but layered crystal structure breaks and reliability deteriorates
Solution Approach 1:
The patent applies beforehand cushioning by pre-coating the lithium nickelate-based positive electrode active material with a protective layer containing Ca, Sr, and P before the material undergoes charge-discharge cycling. This protective layer acts as a cushion that prevents structural breakdown of the layered crystal structure during Li abstraction, allowing high capacity to be achieved while maintaining structural integrity and reliability.
Data Source
AI summary
The present invention provides a positive electrode active material which contributes to the improvement of safety of a secondary battery. This positive electrode active material, which is contained in a nonaqueous electrolyte secondary battery, contains a lithium transition metal composite oxide; the lithium transition metal composite oxide contains Ni, Mn, P, Me (Me is composed of at least one element that is selected from the group consisting of B, Al, Si, Ti, Fe, Co, Sr, Zr, Nb, Mo, Sn, W and Bi), and at least one of Ca and Sr, respectively at specific content ratios; and the ratio m/n of the half-value width m of the diffraction peak of the (003) plane to the half-value width n of the diffraction peak of the (110) plane in an X-ray diffraction pattern obtained by X-ray diffractometry satisfies 0.75≤m/n.