Doped Nickel-Rich Ternary Cathode for Stable High-Nickel Cycling
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Solution Overview
Problem
Nickel-rich ternary materials for lithium-ion batteries face issues such as decreased electrochemical performance, thermal instability, poor conductivity, and rapid capacity decay due to high nickel content, which hinders their application in long-life, high-capacity batteries.
Innovation Solution
A method involving the preparation of a doped nickel-rich ternary material using a solvent-based process with sodium persulfate as an oxidant, thermal polymerization, and dual calcination steps to enhance nickel valence and reduce cation mixing, combined with doping elements like Zr, Nb, Al, F, Mn, and La to improve structural stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel content in ternary materials is increased to achieve higher energy density and capacity, then the energy density and capacity are improved, but the electrochemical performance deteriorates due to cation mixing, thermal stability decreases, and conductivity becomes poor
Solution Approach 1:
The patent applies local quality by introducing doping elements (Al, Zr, Mn, Nb, Ti) at specific lattice positions within the ternary material structure. These dopants are strategically placed to occupy transition metal layers and stabilize the local crystal structure, thereby improving electrochemical performance in specific regions without reducing overall nickel content. This localized modification allows different parts of the material to have different functions: high nickel regions provide capacity while doped regions provide structural stability and conductivity.
Solution Approach 2:
The patent creates composite materials by combining nickel-rich ternary material with multiple doping elements (Al, Zr, Mn, Nb, Ti) in a single crystal structure. This composite approach allows the material to simultaneously exhibit high capacity from nickel and improved stability/conductivity from the dopants. The composite structure integrates the benefits of different elements: nickel for capacity, cobalt for stability, manganese for conductivity, and rare earth elements for structural reinforcement.
2Quantity of substance
If the nickel content in ternary materials is increased to achieve higher energy density, then the capacity is improved, but the thermal stability deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the ternary material through doping. By introducing doping elements at controlled concentrations (0.01-0.1 mol each), the material's thermal properties are altered without changing the fundamental nickel-rich composition. The doping elements raise the decomposition temperature and improve thermal stability by stabilizing the crystal structure at elevated temperatures, allowing the material to maintain its high capacity while resisting thermal degradation.
3Quantity of substance
If the nickel content in ternary materials is increased to achieve higher capacity, then the energy density is improved, but the conductivity deteriorates
Solution Approach 1:
The patent applies local quality by introducing doping elements (Al, Zr, Mn, Nb, Ti) at specific lattice positions within the ternary material structure. These dopants are strategically placed to occupy transition metal layers and stabilize the local crystal structure, thereby improving electrochemical performance in specific regions without reducing overall nickel content. This localized modification allows different parts of the material to have different functions: high nickel regions provide capacity while doped regions provide structural stability and conductivity.
Solution Approach 2:
The doping elements act as intermediaries that facilitate charge transport between nickel sites. Elements like Mn and Nb with appropriate valence states serve as conductive bridges, enabling efficient electron and ion transport through the nickel-rich lattice without requiring a reduction in nickel content. These intermediary dopants create conductive pathways that overcome the inherent poor conductivity of high-nickel materials.
4Reliability
If element doping is performed by coating manganese/aluminum oxide on the surface of lithiated precursor followed by calcination, then the cracking during charge-discharge cycles is reduced, but the uniform distribution of doping elements cannot be guaranteed
Solution Approach 1:
The patent applies preliminary action by incorporating doping elements into the precursor material before lithiation and calcination steps. The doping elements (Al, Zr, Mn, Nb, Ti) are mixed with nickel hydroxide and cobalt hydroxide precursors to form a homogeneous composite precursor. This preliminary incorporation ensures that doping elements are uniformly distributed throughout the material structure from the beginning, preventing the non-uniform distribution that occurs with surface coating methods. The uniform distribution achieved through preliminary action leads to consistent electrochemical performance and reliable cycle stability.
5Ease of manufacture
If dry method is used to directly grind aluminum salt and precursor, then the preparation process is simplified, but the accuracy and uniformity of doping cannot be guaranteed
Solution Approach 1:
The patent applies hydraulic principles by using a solution-based mixing process instead of dry grinding. The nickel salt, cobalt salt, and doping element salts are dissolved in water to form a homogeneous aqueous solution. This liquid medium ensures uniform distribution of all components at the molecular level, achieving superior doping uniformity compared to dry grinding. The solution-based approach maintains ease of manufacture through simple mixing operations while dramatically improving doping accuracy and uniformity.
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 method results in a nickel-rich ternary material with high capacity and long cycle life, effectively addressing the limitations of nickel-rich ternary materials by enhancing thermal stability, conductivity, and cycle performance.
Implementation Method 1
adding an oxidant and a doping element with the solution A to obtain solution B
Implementation Method 2
Subjecting the aerogel D to a first calcinating, and followed by a second calcinating to obtain precursor powder E
Data Source
AI summary
Disclosed are a doped nickel-rich ternary material and a preparation method thereof. The preparation method comprises the following steps: (1) Mixing a nickel source, a cobalt source, and a manganese source in a solvent to obtain a solution A, adding oxidant and doping elements to the solution A, and stirring to obtain solution B; (2) Adding a complexing agent and nitric acid to the solution B and stirring to obtain solution C; (3) Drying the solution C to obtain aerogel D; (4) Grinding the aerogel D, and subjecting it to low-temperature pre-calcinating, and heating the aerogel to perform first calcinating to obtain precursor powder E; (5) Mixing the precursor powder E with a lithium source to obtain a mixture, and subjecting the mixture to second calcinating, grinding, and screening to obtain the doped nickel-rich ternary material.