Gradient-Doped NCM Cathode Coating for Low Gas at High Temperature
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Solution Overview
Problem
Lithium nickel cobalt manganese oxide-based lithium-ion secondary batteries exhibit low high-temperature cycling performance and high gas production during practical use.
Innovation Solution
A positive electrode active material with a lithium nickel cobalt manganese oxide matrix particle doped with elements M2 and M3, coated with an oxide of element M1, where M1, M2, and M3 are selected from specific elements, and concentrations of these elements vary uniformly or decreasingly within the particle, forming a stable structure that reduces surface reactions and gas production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium nickel cobalt manganese oxide is used as positive electrode active material to achieve high energy density, then theoretical capacity is improved, but high-temperature cycling performance deteriorates and gas production increases
Solution Approach 1:
The patent applies local quality by creating a non-uniform doping distribution of element M3 within the matrix particle, where the concentration decreases from the exterior surface toward the core. This gradient distribution allows different regions of the material to have optimized properties: the surface region provides stability against gas production and electrolyte reactions, while the core maintains high capacity for lithium ion insertion/extraction, thus resolving the contradiction between energy density and high-temperature cycling performance
Solution Approach 2:
The patent employs composite material strategy by combining lithium nickel cobalt manganese oxide matrix with multiple doping elements (M2 and M3) and surface coating (oxide of element M1). This multi-component composite structure synergistically improves both energy density and high-temperature cycling performance while suppressing gas production, as the different components fulfill complementary functions in the electrode material system
2Use of energy by moving object
If lithium nickel cobalt manganese oxide is used as positive electrode active material to achieve high energy density, then theoretical capacity is improved, but gas production increases
Solution Approach 1:
The gradient doping distribution of element M3, with higher concentration at the surface and decreasing toward the core, creates local quality differentiation that suppresses gas production at the surface where electrolyte contact occurs, while preserving high capacity in the core region, thus resolving the contradiction between energy density and gas production
Solution Approach 2:
The patent converts the potentially harmful high reactivity of lithium nickel cobalt manganese oxide surface into a benefit by introducing element M3 doping at the surface region, which stabilizes the surface structure and reduces electrolyte decomposition reactions that cause gas production, while maintaining the high capacity characteristics of the bulk material
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 solution enhances the battery's high energy density, high-temperature cycling performance, and high-temperature storage performance by stabilizing the structure and reducing gas production.
Implementation Method 1
effectively improve the structural stability of the positive electrode active material in high-temperature cycling
Implementation Method 2
reduce side reactions of an electrolyte on the surface of the material
Data Source
AI summary
A positive electrode active material and a preparation method thereof, a positive electrode plate, a lithium-ion secondary battery, and a battery module, battery pack, and apparatus containing such lithium-ion secondary battery are provided. The positive electrode active material includes matrix particles and a coating layer covering an exterior surface of the matrix particle, where the matrix particle includes a lithium nickel cobalt manganese oxide, and the coating layer includes an oxide of element M1; the matrix particle is doped with element M2 and element M3, element M2 in the matrix particle is uniformly distributed, and element M3 in the matrix particle has a decreasing concentration from the exterior surface to a core of the matrix particle; and element M1 and element M3 are each independently selected from one or more of Mg, Al, Ca, Ba, Ti, Zr, Zn, and B, and element M2 includes one or more of Si, Ti, Cr, Mo, V, Ge, Se, Zr, Nb, Ru, Rh, Pd, Sb, Te, Ce, and W.