Doped Positive Electrode Materials for Lithium Ion Batteries
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Solution Overview
Problem
Current lithium ion batteries face limitations in energy density and cycling performance due to the modest utilization of theoretical capacity in positive electrode materials, with existing cathode materials not providing significant improvements in energy density and exhibiting high irreversible capacity loss and reduced performance over cycles.
Innovation Solution
Development of a doped positive electrode active material with a composition of Li1+xNiαMnβ-δCoγAδXμO2−zFz, where x, α, β, γ, δ, and μ are within specific ranges, and the use of a method involving co-precipitation to synthesize a layered lithium metal oxide composition with dopants like Mg, Ca, Sr, Ba, Zn, or Cd, along with a metal fluoride coating to enhance cycling stability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional cathode materials (LiCoO2, LiMn2O4, LiFePO4) are used, then manufacturing simplicity is maintained, but energy density and specific capacity are limited
Solution Approach 1:
The patent employs composite cathode materials combining multiple metal elements (Ni, Mn, Co, Al, F) in a layered structure with formula Li1+xNiαMnβ-δCoγAlδXμO2−zFz. This composite approach enables the material to achieve high specific capacity (240-270 mAh/g at C/3 rate) while maintaining structural stability through the synergistic effects of different metals and dopants.
Solution Approach 2:
The patent applies doping strategies where specific metal elements (Al, F, and other divalent metals) are introduced at controlled concentrations (δ ranges from 0.001 to 0.15, μ ranges from 0 to 0.1) into specific positions within the layered structure. This local modification optimizes both capacity and stability without requiring complete restructuring of the material system.
2Quantity of substance
If high capacity cathode materials are used, then energy density improves, but irreversible capacity loss and cycling performance deteriorate
Solution Approach 1:
The patent systematically optimizes multiple compositional parameters including lithium excess (x = 0.01-0.3), metal ratios (α, β, γ), and dopant concentrations (δ, μ, z). By adjusting these parameters, the material achieves a balance between high capacity (240-270 mAh/g) and excellent cycling stability (90% capacity retention after 40 cycles at C/3 rate).
Solution Approach 2:
The patent introduces dopant elements (Al, F, and other metals) as intermediaries that mediate between the high-capacity requirement and cycling stability. These dopants modify the local structure and electronic properties, reducing irreversible capacity loss while maintaining high discharge capacity through improved structural integrity during lithium insertion/extraction cycles.
3Power
If high current delivery is designed for, then power output increases, but total energy and capacity are reduced
Solution Approach 1:
The patent develops cathode materials with dynamic performance characteristics that can adapt to different discharge rates. The optimized composition (Li1+xNiαMnβ-δCoγAlδXμO2−zFz) maintains high capacity utilization across a range of C-rates, achieving 240-270 mAh/g at C/3 while also delivering acceptable performance at higher rates, thus providing dynamic adaptability for different power requirements.
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 doped positive electrode materials achieve high specific capacity, improved cycling performance, reduced irreversible capacity loss, and increased average voltage, leading to enhanced energy storage capabilities suitable for high-energy applications like electric vehicles.
Implementation Method 1
a dopant concentration from about 0.1 to about 10 mole percent wherein the dopant comprises Mg, Ca, Sr, Ba, Zn, Cd or a combination thereof
Implementation Method 2
precipitating a mixed metal hydroxide or carbonate composition from a solution comprising +2 metal cations
Data Source
AI summary
Positive electrode active materials comprising a dopant in an amount of 0.1 to 10 mole percent of Mg, Ca, Sr, Ba, Zn, Cd or a combination thereof are described that have high specific discharge capacity upon cycling at room temperature and at a moderate discharge rate. Some materials of interest have the formula Li1+xNiαMnβ-δCoγAδXμO2−zFz, where x ranges from about 0.01 to about 0.3, δ ranges from about 0.001 to about 0.15, and the sum x+α+β+γ+δ+μ can approximately equal 1.0. The materials can be coated with a metal fluoride to improve the performance of the materials especially upon cycling. The materials generally can have a tap density of at least 1.8 g/mL. Also, the materials can have an average discharge voltage of around 3.6 V.