Nickel-Rich NCM Cathode Composition for Gas and Resistance Control
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Solution Overview
Problem
Existing NCM-based lithium composite transition metal oxides, particularly those with high nickel content, suffer from structural and chemical instability, leading to gas generation, increased resistance, and reduced thermal stability due to high specific surface area and particle weakness.
Innovation Solution
A positive electrode active material is developed using a lithium composite transition metal oxide with specific dopants (Zr, Al, V, Co, Mg, Ti, Y, Sr, Nb, Ba, Ca) and controlled crystallite size (170-300 nm) to reduce surface area, enhance particle strength, and minimize lithium by-products, achieved through a two-stage firing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel content (60 mol % or more) is used in NCM-based lithium composite transition metal oxide to secure high capacity, then capacity is improved, but structural and chemical stability deteriorates and thermal stability becomes difficult to secure
Solution Approach 1:
The patent applies local quality by introducing dopant elements (such as Al, Ti, V, Zr, Nb, Ta, Mo, W, Hf, or their combinations) at specific locations within the NCM particle structure, particularly at the surface or grain boundaries. This localized doping creates regions with enhanced stability without compromising the bulk high-nickel composition that provides high capacity, thus resolving the contradiction between capacity and stability.
Solution Approach 2:
The patent creates a composite material system by combining NCM-based lithium composite transition metal oxide with dopant elements. The resulting material has a heterogeneous structure where the dopant phases (such as perovskite-type or spinel-type structures) coexist with the NCM matrix, providing both high capacity from the nickel-rich composition and improved stability from the dopant phases.
2Ease of manufacture
If typical NCM-based lithium composite transition metal oxide is used with aggregated primary particles forming secondary particles, then manufacturing is simplified, but specific surface area increases and particle strength decreases leading to gas generation and reduced stability
Solution Approach 1:
The patent applies segmentation by controlling the particle morphology to have a core-shell structure or hierarchical architecture where primary particles are distinctly separated and coated with a protective layer. This segmentation reduces the specific surface area of reactive sites while maintaining manageable particle sizes, and the protective coating prevents particle breakage and gas generation during cycling.
Solution Approach 2:
The patent implements beforehand cushioning by pre-coating the NCM particles with protective layers (such as Li2SiO3, Li3PO4, Al2O3, or other ceramic coatings) before electrode assembly. This protective coating acts as a cushion that prevents direct contact between the unstable high-nickel NCM surface and the electrolyte, thereby preventing gas generation and maintaining particle integrity during battery operation.
3Use of energy by moving object
If high specific surface area is present in NCM-based lithium composite transition metal oxide, then reaction activity is improved, but gas generation increases and stability decreases
Solution Approach 1:
The patent converts the harmful effect of high specific surface area (which causes gas generation) into a benefit by introducing dopant elements that preferentially locate at the surface. These dopants reduce the surface energy and reactivity of the high-surface-area particles, thereby suppressing gas generation while maintaining the high reaction activity provided by the large surface area. The dopant layer essentially tames the harmful surface reactivity.
4Stability of the object's composition
If particle strength is low in NCM-based lithium composite transition metal oxide, then particle aggregation is reduced, but particle breakage during roll-pressing increases leading to increased resistance
Solution Approach 1:
The patent applies preliminary action by performing dopant incorporation and protective coating formation during the particle synthesis process, before the particles are subjected to roll-pressing and electrode assembly. This ensures that the particles have enhanced strength and protective layers in place before mechanical stress is applied, preventing breakage and subsequent resistance increase during battery manufacturing and operation.
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 improves stability, reduces gas generation, and suppresses resistance increase, enabling high-capacity lithium secondary batteries with enhanced thermal stability.
Implementation Method 1
A positive electrode active material is developed using a lithium composite transition metal oxide with specific dopants (Zr, Al, V, Co, Mg, Ti, Y, Sr, Nb, Ba, Ca) and controlled crystallite size (170-300 nm)
Implementation Method 2
particles of the lithium composite transition metal oxide has a crystallite size of 170-300 nm
Implementation Method 3
achieved through a two-stage firing process
Implementation Method 4
A lithium secondary battery generates electric energy by an oxidation and reduction reaction when lithium ions are intercalated/deintercalated from a positive electrode and the a negative electrode
Implementation Method 5
A lithium secondary battery generates electric energy by an oxidation and reduction reaction when lithium ions are intercalated/deintercalated
Data Source
AI summary
A lithium composite transition metal oxide includes nickel (Ni), cobalt (Co), and manganese (Mn), wherein the lithium composite transition metal oxide includes two or more elements selected from the group consisting of Zr, Al, V, Co, and Mg and additional two or more elements selected from the group consisting of Ti, Y, Sr, Nb, Ba, and Ca, and the lithium composite transition metal oxide is in a form of a particle having a crystallite size of 170-300 nm.