Copper Negative Electrode Structure for Dendrite-Stable Lithium Batteries
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Solution Overview
Problem
Conventional lithium secondary batteries face insufficient energy density and cycle characteristics, with lithium-metal batteries prone to dendrite formation causing short circuits and capacity reduction, and physical pressure methods increasing battery weight and volume.
Innovation Solution
A lithium secondary battery design featuring a copper negative electrode with a surface roughness of 1.0 µm or less and oriented planes of (200) or (220) planes, eliminating the need for lithium foil and active materials, allowing lithium metal precipitation and electrolytic charge/discharge, enhancing energy density and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional lithium-metal secondary battery precipitates lithium metal on the negative electrode surface, then high energy density is achieved, but dendrite formation occurs causing short circuit and capacity reduction
Solution Approach 1:
The invention changes the physical parameters of the negative electrode by controlling the surface roughness (Rz ≤ 1.0 μm) and crystal orientation ((200) or (220) planes) of the copper foil. These parameter changes modify the lithium precipitation behavior, enabling uniform lithium deposition that prevents dendrite formation while maintaining high energy density.
2Reliability
If physical pressure is applied to keep the negative electrode and separator interface at high pressure to suppress discrete growth, then lithium metal precipitation is controlled, but battery weight and volume increase
Solution Approach 1:
The invention replaces the mechanical pressure application system with a material structure-based solution. Instead of using external mechanical mechanisms to apply pressure, the copper foil's inherent surface properties (roughness and crystal orientation) control lithium precipitation, eliminating the need for additional mechanical components and reducing battery weight.
3Productivity
If a typical secondary battery uses a negative electrode active material, then charge/discharge is performed, but energy density is insufficient
Solution Approach 1:
The invention extracts and eliminates the negative electrode active material from the battery structure. By removing this component and using a copper foil negative electrode instead, the invention reduces unnecessary material mass while maintaining charge/discharge functionality through lithium precipitation and dissolution, thereby improving 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
The battery achieves a high energy density of 350 Wh/kg or more and improved cycle characteristics, with enhanced safety and productivity by eliminating the need for flammable lithium metal and reducing mechanical stress.
Implementation Method 1
charge/discharge is performed by the electrolysis and elution of the resulting precipitated lithium metal
Data Source
AI summary
The purpose of the present invention is to provide a lithium secondary battery having an excellent cycle characteristic. A lithium secondary battery according to an embodiment includes a positive electrode, and a negative electrode not having a negative electrode active material. The negative electrode is configured as Cu having a surface roughness maximum height Rz of 1.0 µm or less and an orientation plane of a plane.