Lithium-Ion Capacitor Electrode Additives for High-Temperature Durability
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Solution Overview
Problem
Conventional lithium ion capacitors face performance reduction due to electrolyte decomposition at high temperatures, leading to gas generation and impaired durability, with existing technologies failing to effectively address these issues.
Innovation Solution
Incorporating sulfonic acid derivatives or sulfurous acid derivatives into the negative electrode active material layer, along with specific pore volume ratios and surface area characteristics, to enhance high-temperature durability and prevent performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium ion capacitors are used, then high power density and high energy density are achieved, but durability is impaired due to electrolyte decomposition at high temperatures
Solution Approach 1:
A coating layer comprising metal fluoride, metal oxide, or metal carbonate is applied to the negative electrode, serving as an intermediary barrier between the electrolyte and the electrode. This coating layer prevents direct contact and chemical reactions, thereby suppressing electrolyte decomposition at high temperatures while maintaining the electrochemical performance of the lithium ion capacitor.
Solution Approach 2:
The invention changes the physical and chemical parameters of the negative electrode surface by applying a coating layer with specific properties (metal fluoride, oxide, or carbonate). This modification alters the surface characteristics to reduce reactivity with the electrolyte, thereby improving high-temperature durability without significantly affecting the overall device performance.
2Quantity of substance
If the negative electrode is designed for high energy density, then capacity is increased, but gas generation occurs due to electrolyte decomposition at high temperatures
Solution Approach 1:
The coating layer acts as a protective intermediary on the negative electrode surface, preventing the electrolyte from decomposing and generating gas. By blocking the direct interaction between the electrolyte and electrode materials, the coating suppresses harmful gas generation while allowing the electrode to maintain its high capacity design.
Solution Approach 2:
The coating layer converts the potentially harmful interface between the electrolyte and negative electrode into a beneficial protective barrier. This barrier not only prevents gas generation but also enhances the overall stability and longevity of the high-capacity electrode design.
3Power
If high power density is achieved through electrode design, then output characteristics are improved, but high-temperature stability deteriorates
Solution Approach 1:
The coating layer serves as a thermal and chemical buffer between the high-performance electrode materials and the electrolyte. This intermediary layer maintains the electrode's high power density characteristics while providing thermal stability and preventing degradation reactions at elevated temperatures.
Solution Approach 2:
The negative electrode is designed as a composite structure combining the active material with a coating layer of metal fluoride, oxide, or carbonate. This composite material approach allows the electrode to maintain its high power output characteristics while the coating provides enhanced thermal and chemical stability.
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 achieves high input/output characteristics and improved durability at elevated temperatures, minimizing gas generation and maintaining superior element characteristics.
Implementation Method 1
Faraday reaction by occlusion/release of lithium ion similar to a lithium ion battery, at the negative electrode
Implementation Method 2
non-Faraday reaction by adsorption/desorption of anion similar to an electrical double layer capacitor, at the positive electrode
Data Source
Figure 1~2
AI summary
A non-aqueous lithium-type power storage element comprising an electrode laminate body and a non-aqueous electrolyte being housed in an external body, the electrode laminate body having a negative electrode body, a positive electrode body and a separator. The negative electrode body has a negative current collector and a negative electrode active material layer that includes a negative electrode active material and that is provided to one or both surfaces of the negative current collector. The negative electrode active material includes a carbon material that can occlude and release lithium ions. The positive electrode body has a positive current collector and a positive electrode active material layer that includes a positive electrode active material and that is provided to one or both surfaces of the positive current collector. The positive electrode active material includes activated carbon. The non-aqueous electrolyte contains, based on the total amount of the non-aqueous electrolyte, 0.5 mol/L or more of a lithium salt, and the negative electrode active material layer includes, per unit weight of the negative electrode active material, 2.6 x 10-6-2, 000 x 10-6 mol/g of a specific sulfur compound.