Aqueous LNMO Cathode Coating for Low Metal Dissolution
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Solution Overview
Problem
The high reactivity of LiNi x Mn 2-x O 4 cathode materials in lithium-ion batteries leads to electrolyte decomposition and manganese and nickel dissolution, resulting in poor cycle life and capacity fade, especially when using aqueous-based formulations, which are not scalable for industrial production without significant material loss.
Innovation Solution
A process involving a specific order and duration for incorporating carbon black, LiNi x Mn 2-x O 4, and a waterborne polymer binder into an aqueous slurry to form a cathode coating with high homogeneity and loading, minimizing metal dissolution and maintaining electrochemical performance, is developed. This includes preparing a dispersion with a water-soluble thickener, adding the cathode active material, and then the binder, with controlled water contact to limit nickel and manganese dissolution below 0.27 ppm and 0.14 ppm, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If aqueous-based formulations are used for cathode preparation, then environmental friendliness and cost are improved, but metal dissolution (manganese and nickel) increases leading to poor cycle life
Solution Approach 1:
The patent introduces water-soluble polymers (CMC, SBR, PAA) as intermediary substances that form protective films on the cathode surface. These polymers act as mediators between the aqueous environment and the LiNi0.5Mn1.5O4 particles, preventing direct contact and dissolution of metal ions while allowing the benefits of aqueous processing. The polymers create a barrier layer that reduces metal dissolution to below detectable levels.
Solution Approach 2:
The patent uses composite material formulations combining LiNi0.5Mn1.5O4 active material with water-soluble polymers (CMC, SBR, PAA) and conductive additives. This composite approach allows the cathode to benefit from both the high voltage properties of spinel and the protective effects of polymer coatings, achieving stable cycling in aqueous environments while maintaining environmental friendliness.
2Use of energy by moving object
If high-voltage spinel LiNi0.5Mn1.5O4 is used to increase energy density, then battery energy density is improved, but electrolyte decomposition and metal dissolution increase
Solution Approach 1:
Water-soluble polymers serve as intermediary protective layers between the high-voltage spinel cathode and the electrolyte. These polymer coatings prevent direct interaction between the high-potential LiNi0.5Mn1.5O4 surface and the electrolyte, thereby preventing decomposition reactions while allowing the high energy density benefits to be realized.
Solution Approach 2:
The patent applies polymer coatings to the cathode particles before assembly into the battery cell. This beforehand cushioning creates a protective barrier that prevents harmful electrolyte decomposition reactions from occurring at the high-voltage interface, cushioning against the harmful effects before they can manifest.
3Reliability
If conventional organic solvent processes are used for cathode manufacturing, then metal dissolution is reduced, but environmental friendliness and scalability are worsened
Solution Approach 1:
The patent fundamentally changes the solvent parameter from organic to water-based, enabling environmentally friendly and scalable manufacturing processes. By combining this parameter change with polymer additives that prevent metal dissolution, the patent achieves both scalability and metal dissolution control simultaneously.
4Reliability
If water-soluble binders like CMC are used to improve electrochemical performance, then metal dissolution is suppressed, but adhesion and mechanical strength deteriorate due to cracking
Solution Approach 1:
The patent merges multiple water-soluble polymers (CMC, SBR, PAA) with complementary properties into a single binder system. CMC provides metal dissolution suppression, while SBR and PAA contribute adhesion and flexibility, preventing cracking. This combination allows the cathode to achieve both metal dissolution suppression and mechanical integrity.
Solution Approach 2:
The patent creates a composite binder system using water-soluble polymers (CMC, SBR, PAA) that work synergistically. This composite binder provides both the metal dissolution suppression needed for stable cycling and the mechanical strength needed to prevent cracking during drying and handling.
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 achieves a cathode with improved specific capacity and electrochemical performance, suitable for high-energy density Li-ion batteries, maintaining discharge voltage stability and preventing metal dissolution, thus enhancing the scalability and performance of Li-ion batteries.
Implementation Method 1
The uniform protective film formed on the cathode surface and the good dispersion of composite electrode components should reduce the contact between LNMO and the electrolyte
Implementation Method 2
preparing a predispersion of carbon black as a conductive material in an aqueous solution of a water soluble thickener
Data Source
Figure 1a)~2
Figure 3a)~3b)
Figure 4a)~4b)
AI summary
It is provided a cathode for a Li-ion battery comprising a conductive substrate in the form of a foil having two sides, wherein at least one of the two sides is coated with an active layer, wherein the active layer comprises a water soluble thickener, a conductive additive, a waterborne polymer binder and an amount equal to or higher than 10 mg/cm2/side of a cathode active material, wherein the cathode active material is LiNixMn2-xO4 wherein x is selected from 0.2, 0.3, 0.4, and 0.5, and the cathode has a specific capacity from 120 to 147 mAh/g-active material, and is capable to maintain an average discharge voltage of 4.7 V versus Li/Li+, tested at C/5 rate. It is also provided a process for the preparation of a cathode for a Li-ion battery, as well as a Li-ion battery comprising the cathode.