Calcium Secondary Cell Temperature Control for SEI Stability
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Solution Overview
Problem
Conventional lithium-based secondary cells and batteries face issues with unsatisfactory lifetime due to the formation of a solid-electrolyte interphase (SEI) and have limited energy storage properties, requiring improvements in SEI quality and energy density, especially when operated under mild temperature conditions.
Innovation Solution
A calcium-based secondary cell is developed, featuring a negative electrode capable of accepting and releasing calcium ions, a positive electrode with calcium-ion accepting and releasing active material, and an electrolyte comprising calcium ions in a non-aqueous solvent, with a temperature control element maintaining the cell between 50°C and 110°C to enhance ionic conductivity and electrochemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium-based secondary cells use organic solvents in the electrolyte, then the cell can operate and provide energy storage, but the solvent decomposes on initial charging to form a solid electrolyte interphase (SEI) layer that is electrically insulating and reduces battery lifetime
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using calcium-based salts (calcium perchlorate, calcium tetrafluoroborate) instead of conventional lithium salts, and employs specific non-aqueous solvents (γ-butyrolactone, dipropyl sulfone) with optimized ratios. This parameter change fundamentally alters the electrochemical behavior to prevent harmful SEI layer formation while maintaining ionic conductivity.
Solution Approach 2:
The patent employs a sacrificial calcium metal layer that is intentionally designed to be consumed during initial charging cycles. This disposable calcium layer reacts with the electrolyte to form a stable, protective interface layer, after which the calcium is depleted and no longer causes harmful decomposition. The sacrificial nature of this layer eliminates long-term SEI formation issues.
2Quantity of substance
If conventional lithium-based secondary cells are designed for higher energy density, then the energy storage capacity increases, but the cell performance under mild temperature conditions deteriorates
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte by selecting solvents with appropriate freezing points and viscosities (γ-butyrolactone, dipropyl sulfone) that remain fluid and conductive at mild temperatures. The calcium-based electrolyte composition maintains optimal ionic conductivity across a wide temperature range, enabling high energy density operation without performance degradation at mild temperatures.
Solution Approach 2:
The patent uses a composite electrolyte system combining calcium salts with specific non-aqueous solvents in optimized proportions. This composite electrolyte formulation achieves both high energy density through calcium's divalent ion capability and maintains operational ease at mild temperatures through the selected solvent properties, resolving the contradiction between energy density and temperature适应性.
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 calcium-based secondary cell achieves higher energy density and capacity, effectively operating under mild temperatures, making it suitable for various applications including information devices and stationary power generation, with improved thermal and electrochemical stability.
Implementation Method 1
a temperature control element, in which the temperature control element is configured to provide heating functionality by bringing and/or maintaining the cell at a temperature between 50°C and 110°C
Implementation Method 2
an electrolyte arranged between the negative electrode and the positive electrode, said electrolyte comprising calcium ions and an electrolyte medium
Data Source
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AI summary
The present disclosure concerns a calcium-based secondary cell comprising: a negative electrode that includes a negative-electrode active material, said negative-electrode active material being capable of accepting and releasing calcium ions; a positive electrode that includes a positive-electrode active material, said positive-electrode active material being capable of accepting and releasing calcium ions; an electrolyte arranged between the negative electrode and the positive electrode, said electrolyte comprising calcium ions and an electrolyte medium, wherein the electrolyte is not solid at standard conditions and wherein the electrolyte medium includes a nonaqueous solvent; and a temperature control element.