Layered Negative Electrode With LTO-SWCNT Coating for Short-Circuit Stability
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Solution Overview
Problem
Lithium titanium oxide (LTO) negative electrodes suffer from low electrical conductivity, hindering the commercialization of next-generation batteries, and there is a need for improved stability against internal short-circuits.
Innovation Solution
A negative electrode structure with a first layer containing a carbonaceous or silicon-based active material and a second layer comprising lithium titanium oxide (LTO) and single-walled carbon nanotubes (SWCNTs), where the LTO layer has a loading amount of 0.1 mAh/cm² or less, ensuring improved electrical conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional negative electrode structure is used, then the battery can operate, but lithium dendrites grow during charging causing short circuits and reduced reliability
Solution Approach 1:
The patent applies preliminary action by pre-coating the negative electrode with an amorphous carbon layer before battery assembly. This carbon layer is formed in advance through pyrolysis of a resin coating, creating a dendrite-resistant surface that prevents lithium dendrite formation during subsequent charging cycles without requiring additional components or complex structures.
Solution Approach 2:
The patent employs a disposable protective carbon coating layer that sacrifices itself to prevent dendrite penetration. The amorphous carbon layer serves as a consumable barrier that can be replaced by re-coating the electrode with resin and re-pyrolyzing, providing a cost-effective solution compared to redesigning the entire electrode structure.
2Use of energy by moving object
If the negative electrode potential is lowered to improve battery voltage, then energy density increases, but lithium metal deposition and dendrite formation are promoted
Solution Approach 1:
The patent introduces an amorphous carbon layer as an intermediary between the negative electrode and the lithium ions. This carbon mediator allows lithium ions to be accommodated in its structure during charging without causing metal deposition or dendrite formation, enabling the use of lower potential negative electrodes while maintaining battery safety.
Solution Approach 2:
The amorphous carbon layer possesses a porous structure with numerous fine holes that can accommodate lithium ions. This porous configuration allows lithium to be stored within the carbon matrix rather than depositing as metal, preventing dendrite formation while maintaining the low potential necessary for high energy density.
3Reliability
If existing coating methods are used, then the electrode can be protected, but the coating process is complex and difficult to control
Solution Approach 1:
The patent replaces complex mechanical coating processes with a thermal decomposition method. Instead of applying carbon coatings through mechanical means such as sputtering or CVD, the invention uses pyrolysis of an organic resin coating at relatively low temperatures (below 1000°C), simplifying the manufacturing process and making it more controllable.
Solution Approach 2:
The patent changes the parameters of the coating process by using low-temperature pyrolysis instead of high-temperature or complex chemical vapor deposition methods. The resin coating is heated to 100-1000°C to decompose and form the amorphous carbon layer, creating a simple controllable process that can be easily integrated into existing battery manufacturing lines.
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 electrode structure enhances electrochemical performance, charge/discharge efficiency, and stability against internal short-circuits by utilizing SWCNTs to improve conductivity, even with a minimal LTO layer.
Implementation Method 1
it has been found that smooth insertion and extraction of lithium can be achieved by forming an amorphous carbon layer having a specific structure on the surface of a negative electrode, and lithium dendrites can be effectively inhibited by the amorphous carbon layer
Implementation Method 2
the resin coating is pyrolyzed
Data Source
Figure 1
AI summary
The present disclosure relates to a negative electrode and a secondary battery including the same. The negative electrode includes a current collector, a first negative electrode active material layer disposed on at least one surface of the current collector, and a second negative electrode active material layer disposed on the first negative electrode active material layer. Particularly, the second negative electrode active material layer includes lithium titanium oxide (LTO) and single-walled carbon nanotubes (SWCNTs), the first negative electrode active material layer includes a negative electrode active material other than the lithium titanium oxide (LTO), and the second negative electrode active material layer has a loading amount of 0.1 mAh/cm2 or less.