Lithium-Ion Battery Negative Electrode Without Active Material
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges with the formation of lithium dendrites on the negative electrode, leading to short circuits and reduced cycle characteristics, and the use of carbon-based active materials increases costs and decreases energy density.
Innovation Solution
The battery design eliminates the carbon-based active material layer by directly depositing lithium on the current collector, utilizing an electrolyte solution with fluorine-containing salts or organic compounds like lithium tetrafluoroborate or fluoroethylene carbonate to prevent dendrite formation, and incorporates a spacer with high porosity to increase deposition area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an active material layer formed of carbon material is applied onto a current collector, then the negative electrode can prevent lithium dendrite formation, but the fabrication cost increases and energy density decreases
Solution Approach 1:
The invention extracts and removes the carbon-based active material layer from the negative electrode structure, eliminating the need for expensive materials and complex fabrication processes while directly exposing the current collector to the electrolyte solution for lithium ion insertion/extraction
Solution Approach 2:
The invention changes the fundamental parameter of the negative electrode composition by replacing carbon-based active material with a metal current collector surface, and modifies the electrolyte solution composition by adding specific additives to enable dendrite-free lithium deposition
2Reliability
If an active material layer is formed using facilities such as mixer, coater, and dryer, then the negative electrode can function properly, but the fabrication time increases
Solution Approach 1:
The invention removes the entire active material layer formation process, eliminating the need for mixer, coater, and dryer facilities, thereby drastically reducing fabrication time while maintaining negative electrode functionality through direct lithium deposition on the current collector
Solution Approach 2:
The current collector surface serves its dual function as both the structural support and the active site for lithium ion insertion/extraction, eliminating the need for separate active material layers and their associated fabrication processes
3Use of energy by moving object
If lithium is directly deposited on a current collector without carbon-based active material, then the energy density increases, but lithium dendrites form causing short circuits
Solution Approach 1:
The invention introduces specific additives into the electrolyte solution that act as intermediaries to mediate between the lithium ions and the current collector surface, controlling the deposition process to prevent dendrite formation while maintaining high energy density
Solution Approach 2:
The invention changes the electrolyte solution composition by adding specific additives that modify the deposition parameters of lithium on the current collector, enabling dendrite-free deposition and maintaining reliability while achieving high energy density
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
This approach reduces lithium dendrite formation, enhances cycle characteristics, and increases energy density without increasing costs, allowing for a more efficient and cost-effective lithium-ion secondary battery with improved capacity per unit mass and volume.
Implementation Method 1
A deposit containing lithium is deposited on a surface at the time of charging
Implementation Method 2
The electrolyte solution contains fluorine. The negative electrode current collector has a function of making a deposit containing lithium to be deposited on a surface at the time of charging
Data Source
AI summary
A lithium-ion secondary battery with no negative electrode active material is provided. One embodiment of the present invention is a lithium-ion secondary battery including a positive electrode, a negative electrode, an electrolyte solution, and a separator between the positive electrode and the negative electrode. The negative electrode includes a negative electrode current collector which includes a region in direct contact with at least one of the electrolyte solution and the separator. The electrolyte solution contains fluorine. The negative electrode current collector has a function of making a deposit containing lithium to be deposited on a surface in charging. Furthermore, a spacer may be provided between the separator and the negative electrode. The electrolyte solution may contain an organic compound containing fluorine. Supply of fluorine from the electrolyte solution to lithium deposited on the surface of the negative electrode can suppress deposition of lithium dendrites (whiskers) in further deposition.