Dry Surface Doping of Cathode Materials to Prevent Li Loss
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Solution Overview
Problem
Conventional surface doping processes for lithium-ion battery cathode materials face issues such as structural damage from solvents, high costs due to organic solvents, and inaccurate dosing and non-uniform distribution of dopant salts, leading to capacity degradation and short cycle life.
Innovation Solution
A dry surface doping process using a metal oxide dopant, which is mixed with the cathode material and calcined in dry air or oxygen, eliminating solvent contact and evaporation steps, ensuring accurate dosage and uniform distribution for enhanced structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet surface doping process is used, then dopant can be applied to cathode material surface, but solvent may leach Li ions resulting in Li deficiency and phase change
Solution Approach 1:
The patent employs a dry surface doping process that eliminates solvent contact with the cathode material surface. By using a dry mixing approach followed by calcination in an oxygen atmosphere, the method prevents water-induced Li ion leaching and associated phase changes, while still achieving uniform dopant distribution through the dry mixing and thermal processing steps.
2Manufacturing precision
If organic solvent is used in wet surface doping, then dopant can be applied to cathode material surface, but manufacturing cost increases significantly
Solution Approach 1:
The patent replaces expensive organic solvents with inexpensive dry mixing and calcination processes. The method uses readily available materials and straightforward thermal processing to achieve dopant application, eliminating the need for costly organic solvents and their associated handling, evaporation, and waste management requirements.
3Ease of manufacture
If dopant salt is used in dry surface doping, then doping can be performed without solvent, but dosing accuracy and distribution uniformity are poor
Solution Approach 1:
The patent transforms the dopant from salt form to oxide form, which enables accurate dosing through controlled calcination processes. The oxide precursor allows for precise thermal processing parameters (temperature, time, atmosphere) to be applied, ensuring accurate dopant incorporation and uniform distribution without the handling and dosing difficulties associated with salt forms.
4Stability of the object's composition
If bulk doping approach is used, then crystal structure can be stabilized, but specific capacity decreases due to electrochemically inactive dopant
Solution Approach 1:
The patent applies dopant specifically to the surface region of the cathode material rather than throughout the bulk. This localized surface doping provides crystal structure stabilization at the critical surface interface where phase changes occur, while leaving the interior bulk material free of dopant to maintain its full electrochemical capacity and active lithium content.
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 dry surface doping process improves cathode material stability, reducing crack formation and capacity degradation, and maintaining or improving electrochemical performance compared to wet doping methods.
Implementation Method 1
calcining the mixture in dry air or a dry oxygen atmosphere to obtain the doped cathode material
Data Source
AI summary
A doped cathode material for lithium-ion batteries is disclosed. Methods and systems are further provided for doping a cathode material for use in a lithium-ion battery. In one example, the doping may be a dry surface doping process. In some examples, dopants may stabilize a crystal structure of the cathode material and may result in fewer side reactions with an electrolyte as compared to an undoped cathode material. As such, cycling performance and capacity retention may be improved relative to the undoped cathode material. Further, in some examples, the doped cathode material produced with the dry surface doping process may have improved cycling performance and capacity retention relative to a comparable doped cathode material produced with a wet surface doping process.