Nonaqueous Lithium Power Storage Element High-Temperature Stability
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Solution Overview
Problem
Conventional lithium ion capacitors face challenges in achieving high input/output characteristics over a wide temperature range, durability at high temperatures, and safety, with existing solutions either lacking in durability or safety considerations.
Innovation Solution
A nonaqueous lithium-type power storage element is developed using a specific carbon material as the negative electrode active material, doped with lithium ions and sulfite or sulfate ions, combined with a specified electrolyte and separator, to enhance performance and safety across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium ion capacitors use existing electrolyte compositions, then initial properties are acceptable, but durability at high temperatures deteriorates due to gas generation and performance reduction
Solution Approach 1:
The patent modifies the electrolyte composition by specifying precise proportions of cyclic carbonate (15-30 vol%), chain carbonate (65-80 vol%), and lithium salt (0.5-2.0 mol/L), which changes the chemical parameters to reduce gas generation at high temperatures while maintaining initial performance
Solution Approach 2:
The patent uses a composite electrolyte system combining multiple carbonate solvents (cyclic and chain) with lithium salts, creating a synergistic mixture that provides both high-temperature stability and good initial electrochemical properties
2Power
If lithium ion capacitors are designed for high output characteristics, then power density improves, but energy density decreases due to design compromises
Solution Approach 1:
The patent applies different characteristics to different electrodes: the positive electrode uses activated carbon optimized for high power density with specific surface area (2000-4000 m²/g) and pore volume (0.3-0.8 cm³/g), while the negative electrode uses carbon material optimized for lithium ion insertion, creating local optimization that balances overall power and energy density
3Adaptability or versatility
If lithium ion capacitors operate in wide temperature ranges, then adaptability improves, but performance deteriorates due to electrolyte conductivity reduction at low temperatures and gas generation at high temperatures
Solution Approach 1:
The patent adjusts electrolyte composition parameters including the ratio of cyclic to chain carbonate (15-30 vol% vs 65-80 vol%) and lithium salt concentration (0.5-2.0 mol/L) to optimize performance across wide temperature ranges from -30°C to 60°C
Solution Approach 2:
The patent uses an all-carbon electrode system (activated carbon positive electrode and carbon material negative electrode) that creates a chemically inert environment resistant to electrolyte decomposition, reducing gas generation even at high temperatures up to 60°C
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, reduced gas generation at high temperatures, and improved safety, ensuring excellent electrochemical properties and durability in both high and low temperature environments.
Implementation Method 1
Faraday reaction by occlusion/release of lithium ions similar to a lithium ion battery, at the negative electrode
Implementation Method 2
non-Faraday reaction by adsorption/desorption of anions similar to an electrical double layer capacitor, at the positive electrode
Implementation Method 3
a nonaqueous electrolyte comprising a lithium ion-containing electrolyte
Data Source
AI summary
A non-aqueous lithium-type power storage element obtained by a non-aqueous liquid electrolyte and an electrode laminate having a negative electrode body, a positive electrode body, and a separator being accommodated in an exterior body, wherein: the negative electrode body includes a negative electrode current collector and a negative electrode active material including a carbon material capable of occluding and releasing lithium ions.