NCM Cathode Precursor Composition for Dense, Strong Secondary Particles
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Solution Overview
Problem
Existing NCM-based positive electrode active materials face issues with low density, low ionic conductivity, and poor particle strength due to large primary particle sizes and porous secondary particles, which affect battery performance.
Innovation Solution
A method of preparing a positive electrode active material precursor by co-precipitation without inert gases, forming nickel and cobalt in non-oxidized hydroxide forms and manganese in oxidized form, followed by sintering with a lithium source to create a Li-rich NCM-based positive electrode active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a precursor is synthesized by conventional co-precipitation method using inert gases, then the synthesis process is stable and controllable, but the resulting material has large primary particle sizes and porous secondary particles leading to low density
Solution Approach 1:
The patent applies inert atmosphere by conducting the co-precipitation synthesis in an inert gas environment (nitrogen or argon), which prevents oxidation of metal ions during precipitation. This enables stable and controllable synthesis while achieving small primary particle sizes (50-500 nm) and high density (2.0-3.0 g/cc) through uniform nucleation and growth without oxidative aggregation.
2Ease of manufacture
If the precursor is synthesized without inert gases, then the synthesis process is simpler and more cost-effective, but the material exhibits poor particle strength and particle breakage during rolling
Solution Approach 1:
The patent employs inert atmosphere during co-precipitation to prevent oxidation of metal ions, which forms precursors with uniform composition and strong interparticle bonding. This results in excellent particle strength that prevents breakage during subsequent rolling and electrode fabrication, while the process remains relatively simple and cost-effective.
Solution Approach 2:
The patent optimizes synthesis parameters including pH control (8-10), temperature (20-50°C), and metal ion concentration ratios to achieve precise compositional control. These parameter optimizations enhance particle strength and structural integrity without requiring complex additional processing steps.
3Reliability
If cobalt content is increased to improve charge/discharge characteristics and life characteristics, then excellent electrochemical performance is achieved, but the cost increases significantly
Solution Approach 1:
The patent systematically optimizes the composition parameters of NCM materials, specifically the ratios of nickel, cobalt, and manganese elements. By precisely controlling these compositional parameters, the patent achieves excellent charge/discharge characteristics and long cycle life while significantly reducing cobalt content, thereby lowering material costs.
Solution Approach 2:
The patent develops composite NCM materials that combine nickel, cobalt, and manganese in optimized ratios, leveraging the complementary properties of each element: nickel for high capacity, cobalt for structural stability, and manganese for thermal stability. This composite approach reduces dependence on expensive cobalt while maintaining excellent electrochemical performance.
4Ease of manufacture
If the precursor has large primary particle sizes, then the synthesis is easier to control, but the ionic conductivity is low and battery performance deteriorates
Solution Approach 1:
The patent applies segmentation by controlling the formation of small primary particles (50-500 nm) through optimized co-precipitation conditions including pH control, temperature, and addition rate. These small primary particles are then aggregated into secondary particles with controlled morphology, creating a segmented structure that provides numerous interfaces for ion transport and maintains high ionic conductivity while remaining easy to manufacture.
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 resulting material exhibits high density, excellent particle strength, and improved battery performance with high capacity, efficiency, and rate capability.
Implementation Method 1
a positive electrode active material precursor synthesized by a co-precipitation method, wherein the precursor is mainly in the form of hydroxide or carbonate
Implementation Method 2
the manganese (Mn) is in an oxidized form
Implementation Method 3
mixing the positive electrode active material precursor with a lithium raw material; and sintering at 750° C. to 1,000° C. after the mixing to form a lithium composite transition metal oxide
Data Source
AI summary
A method of preparing a positive electrode active material precursor for a secondary battery includes continuously adding a nickel (Ni), cobalt (Co), and manganese (Mn) transition metal cation-containing solution, an alkaline solution, and an ammonium ion-containing solution to a reactor, and forming a positive electrode active material precursor, in which nickel (Ni) and cobalt (Co) are in non-oxidized hydroxide forms and manganese (Mn) is in an oxidized form, by co-precipitation while a gas is not added or an oxygen-containing gas is continuously added to the reactor. A positive electrode active material precursor for a secondary battery is also provided which includes nickel (Ni), cobalt (Co), and manganese (Mn), wherein the nickel (Ni) and the cobalt (Co) are in non-oxidized hydroxide forms, and the manganese (Mn) is in an oxidized form.