NMC Battery Electrode Binder Coating Against Alkaline Resistance Rise
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Solution Overview
Problem
Nonaqueous electrolyte batteries with high alkaline components experience increased internal resistance due to side reactions, leading to deterioration in input-output characteristics.
Innovation Solution
An electrode with a lithium-containing nickel-cobalt-manganese composite oxide active material and a binder derived from vinylidene fluoride, which interacts with the alkaline components to prevent resistance increase by coating the active material surface, thereby maintaining effective reaction areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large amount of alkaline component is contained in the electrode to improve capacity, then the battery capacity increases, but side reactions occur between the active material and alkaline component leading to increased internal resistance
Solution Approach 1:
A coating layer comprising a polymer with a repeating unit derived from vinylidene fluoride is formed on the surface of the active material particles. This coating layer acts as an intermediary between the alkaline component and the active material, preventing direct contact and side reactions while allowing ionic transport, thus resolving the contradiction between maintaining high alkaline component content and preventing resistance increase
2Quantity of substance
If side reactions occur between active material and alkaline component, then gas is generated and active material is covered, but this leads to increased internal resistance and deterioration of input-output characteristics
Solution Approach 1:
The vinylidene fluoride-derived polymer coating serves as a protective intermediary that prevents the active material surface from being covered by reaction products while allowing efficient ionic transport. This maintains both active material coverage and good input-output characteristics by eliminating the harmful side reactions
3Area of stationary object
If the active material surface is covered with compounds from side reactions, then the reaction area is reduced, but this increases internal resistance
Solution Approach 1:
The polymer coating layer acts as an intermediary protective layer that prevents the formation of resistive compounds on the active material surface. It maintains the effective reaction area by preventing surface coverage with side reaction products while simultaneously preventing resistance increase through its protective function
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 solution effectively prevents the increase in internal resistance, enhancing the input-output characteristics and cycle life of the nonaqueous electrolyte batteries.
Implementation Method 1
a binder containing a polymer, the polymer having a repeating unit derived from vinylidene fluoride, and having one or more peaks in the nuclear magnetic resonance spectrum with fluorine-19 as the detection nucleus are located in the range of −90 ppm or higher and −88 ppm or lower
Data Source
AI summary
An electrode includes an active material-containing layer that contains active material particles and a binder containing a polymer. The active material particles contain a lithium-containing nickel-cobalt-manganese composite oxide represented by LiaNi(1−x−y)CoxMnyMzO2 where 0.9≤a≤1.2, 0<x≤0.5, 0<y≤0.5, 0<z≤0.1, x≥y, 0.4≤1−x−y≤0.8, and M is at least one element selected from B, Mg, Al, Si, Ca, Ti, Zn, Zr, Sn, and W. The polymer has a repeating unit derived from vinylidene fluoride and one or more peaks in a nuclear magnetic resonance spectrum with fluorine-19 as a detection nucleus are located in the range of −90 ppm or higher and −88 ppm or lower.