Carbon-Layered Lithium Negative Electrode for Stable High-Energy Cells
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Solution Overview
Problem
Lithium secondary batteries face issues with electrolyte decomposition and lithium dendrite formation, leading to low coulombic efficiency and short cycle life, especially when using lithium metal negative electrodes.
Innovation Solution
A negative electrode comprising a crystalline carbon layer, an amorphous carbon layer with a network structure, and lithium ions or lithium carbide compounds intercalated into the amorphous carbon layer, with lithium metal electrodeposited around these compounds, formed through a process involving oxygen plasma treatment, metal organic framework coating, and high-temperature calcination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium metal negative electrode is used to achieve high theoretical capacity (3860 mAh/g) and high energy density, then the energy density and capacity are improved, but electrolyte decomposition reaction and lithium dendrite formation occur leading to low coulombic efficiency
Solution Approach 1:
An artificial solid electrolyte interphase (SEI) coating layer is introduced as an intermediary between the lithium metal negative electrode and the electrolyte. This coating layer, comprising inorganic particles (such as Al2O3, SiO2, TiO2, or ZrO2) and organic binder, acts as a protective mediator that prevents direct contact between the reactive lithium metal and the electrolyte, thereby suppressing electrolyte decomposition and lithium dendrite formation while maintaining high energy density
Solution Approach 2:
The negative electrode is designed as a composite structure combining lithium metal active material with an artificial SEI coating layer. The coating layer itself is a composite of inorganic particles dispersed in an organic binder matrix. This composite material approach allows the system to simultaneously achieve high energy density from the lithium metal while the composite coating provides protective functions to maintain coulombic efficiency
2Reliability
If lithium metal reacts with electrolyte to form solid electrolyte interphase (SEI) on the surface, then the protective layer is formed, but continuous consumption of lithium metal and electrolyte occurs due to repeated SEI cracking and re-formation
Solution Approach 1:
The artificial SEI coating layer is formed preliminarily (before battery operation) through a coating process involving dispersion of inorganic particles in organic binder and application to the lithium metal surface. This pre-formed stable coating prevents the need for repeated SEI formation and cracking cycles that would otherwise consume lithium metal and electrolyte during initial charging cycles
Solution Approach 2:
The mechanical properties of the SEI layer are changed by incorporating inorganic particles with appropriate hardness and elasticity, as well as using organic binders with flexible molecular structures. These parameter changes make the coating layer more resistant to cracking during volume expansion and contraction of lithium metal during cycling, preventing the cycle of cracking and re-formation that leads to substance loss
3Shape
If lithium dendrite protrusion grows three-dimensionally from the negative electrode surface, then the active material distribution is formed, but large loss of active material occurs and internal short circuit may happen
Solution Approach 1:
The artificial SEI coating layer provides preliminary anti-action by creating a physical barrier that prevents lithium dendrite protrusion from growing into the electrolyte and separator. The coating layer's mechanical strength and adhesion to the lithium metal surface prevent dendrite initiation and growth, thereby preventing internal short circuits before they can occur
Solution Approach 2:
The organic binder component of the artificial SEI coating forms a flexible thin film that can accommodate the volume changes of lithium metal during cycling without cracking. This flexible film maintains continuous coverage over the lithium metal surface, preventing dendrite formation and the associated harmful effects of active material loss and internal short circuits
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 fundamentally suppresses electrolyte decomposition and lithium dendrite growth, enabling high capacity and energy characteristics comparable to conventional lithium metal batteries, suitable for next-generation applications.
Implementation Method 1
a step of subjecting a crystalline carbon fabric containing plural carbon fibers to an oxygen plasma treatment to oxidize the surface
Implementation Method 2
a lithium ion or lithium carbide compound intercalated into the amorphous carbon layer
Implementation Method 3
a lithium metal electrodeposited around the lithium ion or lithium carbide compound
Data Source
AI summary
Disclosed is a negative electrode for a lithium secondary battery that enables the provision of a lithium secondary battery having a higher energy density and can fundamentally prevent the electrolyte decomposition reaction and the lithium dendrite formation, a method for manufacturing the same and a lithium secondary battery including the same.