Anode-Free Battery Carbon Layer for Lithium Dendrite Suppression
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Solution Overview
Problem
Existing secondary batteries suffer from insufficient energy density and cycle characteristics due to dendrite formation on the negative electrode and the need for mechanical pressure to suppress lithium metal precipitation, which increases weight and decreases energy density.
Innovation Solution
A battery design featuring a negative electrode without active material, a separator, and a carbon layer between the separator and negative electrode, with the carbon layer's capacity limited to 22% of the positive electrode's capacity, facilitated by an electrolytic solution, to uniformly deposit and dissolve lithium metal, suppressing dendrite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is deposited on the negative electrode surface to achieve high energy density, then energy density is improved, but dendrites form on the negative electrode surface causing short-circuiting and capacity loss
Solution Approach 1:
A carbon layer is introduced as an intermediary between the negative electrode current collector and the separator. This carbon layer serves as a buffer that accommodates lithium metal deposition while preventing direct contact between lithium dendrites and the separator, thereby maintaining both high energy density and reliable cycle characteristics
Solution Approach 2:
The carbon layer is designed with a porous structure that allows lithium ions to penetrate and deposit within the carbon matrix. This porous structure provides pathways for lithium ion transport while the carbon framework prevents dendrite formation, resolving the contradiction between energy density and cycle stability
2Reliability
If physical pressure is applied to suppress discrete growth during lithium metal precipitation, then dendrite formation is suppressed, but the weight and volume of the battery increase
Solution Approach 1:
The mechanical pressure system is replaced with a carbon layer structure that inherently suppresses dendrite growth through its physical and chemical properties. The carbon layer provides a stable interface that prevents discrete growth without requiring continuous mechanical pressure, thereby reducing battery weight and volume
Solution Approach 2:
The carbon layer acts as a mediator between the lithium metal and the external environment, providing structural support and dendrite suppression without requiring additional mechanical pressure mechanisms. This intermediary structure achieves reliability without the weight penalty of mechanical pressure systems
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 design achieves high energy density and improved cycle characteristics by preventing dendrite growth and reducing internal resistance, resulting in a safer and more efficient battery performance.
Implementation Method 1
charging and discharging are performed by exchanging lithium ions between the positive electrode active material and the negative electrode active material
Implementation Method 2
transferring metal ions between a positive electrode and a negative electrode
Data Source
AI summary
A battery is provided that has excellent energy density and excellent cycle characteristics early in the cycle. The battery in one aspect of the present invention comprises: a positive electrode; a negative electrode free of a negative electrode active material; a separator that is disposed between the positive electrode and the negative electrode; and a carbon layer that is disposed between the separator and the negative electrode, wherein the capacity of the carbon layer is 22% or less of the capacity of the positive electrode.