MOF Intermediate Layer for Li Dendrite Control in Lithium Ion Batteries
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in low-temperature environments where the negative electrode's absorption capability is reduced, leading to lithium (Li) ion precipitation and the formation of dendrites, which can cause heat generation issues when the battery is heated.
Innovation Solution
A lithium ion secondary battery design incorporating a first intermediate layer with a metal organic framework (MOF) and a second electrically insulating intermediate layer, both porous, to isolate the MOF from the negative electrode, allowing it to oxidize and absorb Li dendrites, thereby reducing their growth and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If charging with high current is performed in low-temperature environment, then charging speed is improved, but Li dendrite formation occurs due to insufficient absorption capability of negative electrode
Solution Approach 1:
A coating layer containing a specific metal organic framework (MOF) is applied to the negative electrode surface. This MOF acts as an intermediary substance that preferentially reacts with Li ions during charging, forming a stable interface that prevents direct Li metal deposition and dendrite formation while maintaining high charging rates even in low-temperature environments.
Solution Approach 2:
The invention changes the chemical and physical parameters of the negative electrode surface by introducing a MOF coating with specific properties (porous structure, specific surface area, chemical composition). This modification alters the electrode's interaction with Li ions, enabling safe high-current charging by controlling Li ion distribution and reaction kinetics at the electrode interface.
2Quantity of substance
If Li dendrite grows in the battery, then charge capacity increases temporarily, but heat generation reaction occurs when battery is heated
Solution Approach 1:
The MOF coating is applied in advance to the negative electrode to prevent Li dendrite formation before it can occur. By establishing this protective layer during battery manufacturing, the system proactively counteracts the tendency toward dendrite growth and subsequent heat generation, eliminating the harmful effect before it manifests.
3Productivity
If MoF is directly contacted with negative electrode, then Li ion absorption is improved, but electrical short circuit occurs between MoF and negative electrode
Solution Approach 1:
The MOF is confined to a specific localized region (the coating layer on the negative electrode surface) where it performs its intended function of Li ion absorption and dendrite prevention. This spatial localization ensures that the MOF's electrical properties do not cause short circuits while maintaining its beneficial chemical interaction with Li ions at the critical electrode interface.
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 battery effectively reduces Li dendrite formation and heat generation, enhancing its performance and safety by allowing the MOF to oxidize and absorb Li dendrites, even in high-temperature conditions, thus improving its operational stability.
Implementation Method 1
a portion of Li dendrite in contact with the negative electrode (a root so to speak) may be oxidized by the negative electrode. Namely, the Li metal is expected to return to Li ions
Implementation Method 2
Both the positive electrode and the negative electrode are respectively held in an outer pack. The positive electrode, the separator, and the negative electrode are wound around a core in this state to form a wound roll, and then the wound roll is put in the outer pack.
Implementation Method 3
The second layer is formed of lithium ions coordinated to the carboxylate anion
Data Source
AI summary
A lithium ion secondary battery includes at least a positive electrode, a separator, a first intermediate layer, a second intermediate layer, and a negative electrode. The separator is arranged between the positive electrode and the negative electrode. The first intermediate layer is arranged between the separator and the negative electrode. The second intermediate layer is arranged between the first intermediate layer and the negative electrode. The first intermediate layer and the second intermediate layer are each a porous layer. The first intermediate layer contains at least a metal organic framework. The second intermediate layer is electrically insulating.