High-Nickel Cathode Composition for Stable Li-Ion Battery Cycling
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Solution Overview
Problem
Lithium-ion batteries with high-nickel or high-voltage ternary materials face issues of poor structure stability and cycling stability due to gas generation, leading to poor cycling performance.
Innovation Solution
A cathode material with composition Li 1+a (Ni x Co y Mn z G b )T c O 2 is prepared through a three-stage sintering process, where elements are distributed differently based on temperature, enhancing particle strength and crystal structure stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-nickel or high-voltage ternary materials are used to increase energy density, then energy density is improved, but structure stability deteriorates leading to poor cycling stability and increased gas generation
Solution Approach 1:
The patent applies local quality by implementing a gradient distribution of elements within the cathode material particles. The core region contains different compositional characteristics compared to the surface region, creating localized variations in material properties. This gradient structure allows the core to maintain structural stability while the surface interacts with the electrolyte, thereby improving cycling stability without sacrificing energy density.
Solution Approach 2:
The patent employs composite materials by combining multiple elements (nickel, cobalt, manganese, and additional dopant elements) within a single cathode material structure. This composite approach creates a multi-element ternary material where each element contributes specific properties: nickel provides high capacity, cobalt enhances structural stability, manganese improves safety and stability, and dopant elements further optimize performance. The synergistic combination resolves the contradiction between energy density and cycling stability.
2Use of energy by moving object
If high-nickel or high-voltage ternary materials are used to increase energy density, then energy density is improved, but structure stability deteriorates resulting in gas generation
Solution Approach 1:
The gradient distribution of elements creates localized regions with different chemical compositions and properties. The surface region is specifically designed to have lower nickel content and higher content of stabilizing elements, which reduces the intensity of side reactions with the electrolyte and suppresses gas-generating reactions at the particle surface, while the core maintains high nickel content for energy density.
Solution Approach 2:
The patent converts the potential harm of high-nickel content (which causes structure instability and gas generation) into a benefit by strategically positioning nickel-rich regions in the core away from the electrolyte interface. The surface is engineered with stabilizing elements that prevent gas generation, thus transforming the problematic high-nickel characteristic into an advantage for energy density while eliminating its harmful effects through spatial separation.
3Reliability
If multi-element doping and surface coating are applied to improve structure stability, then cycling stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the doping and coating processes into a single integrated manufacturing step. Instead of separately doping the material and then applying a surface coating, the invention performs simultaneous doping and coating in one sintering process by co-precipitating all necessary elements together. This integration significantly reduces manufacturing complexity while maintaining the dual benefits of bulk doping for structural stability and surface coating for protecting against gas generation.
Solution Approach 2:
The patent applies preliminary action by pre-mixing and co-precipitating all dopant elements and coating materials with the main cathode material precursors before the sintering process. This preliminary preparation ensures uniform distribution of all elements throughout the material, including at the surface, eliminating the need for subsequent separate coating steps and simplifying the overall manufacturing process while achieving both bulk and surface modification.
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 cathode material exhibits a small shift in peak position after cycling, indicating high particle strength and improved Li-ion transmission, resulting in better cycling performance and capacity retention.
Implementation Method 1
performing a first sintering treatment on the mixture I in an oxygen-containing atmosphere at a constant temperature T1 for a constant temperature duration t1
Implementation Method 2
performing a second sintering treatment on the mixture III in an oxygen-containing atmosphere at a constant temperature T2 for a constant temperature duration t2
Implementation Method 3
indicating high particle strength and improved Li-ion transmission
Data Source
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AI summary
The present disclosure relates to the field of lithium-ion batteries and discloses a cathode material, a preparation method therefor, and a lithium-ion battery. The cathode material has a composition represented by Li1+a(NixCoyMnzGb)TcO2, where 0.02≤a≤0.1,0.6≤x≤1, 0<y≤0.5, 0<z≤0.5, 0<b≤0.02, 0<c<0.02. A characteristic peak (003) before and after 80 cycles at 45°C satisfies 0°≤△P=Ppre-Ppost≤0.2°. This cathode material has a high particle strength and more excellent crystal structure stability, which makes cycling performance of the cathode material significantly improved.