Solid-State Lithium Battery Anode Composite for Pore-Free Interfaces
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Solution Overview
Problem
All-solid lithium secondary batteries face challenges in improving energy density and extending the lifetime and safety due to the use of bulky solid electrolytes and the formation of pores between the electrolyte and metal layers, which reduces their operational efficiency and increases the risk of lithium dendrite formation.
Innovation Solution
Incorporating graphitized platelet carbon nanofibers and silver nanoparticles in the negative electrode active material layer to enhance lithium ion mobility and storage, thereby improving charge/discharge efficiency and reducing the need for external pressure, which also lowers the amount of silver required, enhancing price competitiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a metal layer capable of forming an alloy with lithium is used as a negative electrode active material layer to improve energy density, then energy density is improved, but pores are generated between the solid electrolyte and the metal layer which adversely affects battery operation
Solution Approach 1:
The negative electrode active material layer is designed as a composite structure containing both the metal layer (lithium metal or lithium alloy) and graphitized platelet carbon nanofibers. This composite structure allows the metal layer to provide high energy density while the carbon nanofibers fill and seal the pores that form between the solid electrolyte and metal layer, maintaining reliable battery operation.
Solution Approach 2:
The graphitized platelet carbon nanofibers are specifically positioned within the negative electrode active material layer to address the pore formation issue locally. The nanofibers are distributed throughout the metal layer to seal pores at the interfaces between solid electrolyte and metal, providing localized structural support and preventing harmful pore formation while preserving the overall high energy density of the metal layer.
2Quantity of substance
If lithium metal is used as a negative electrode active material layer to improve energy density, then energy density is improved, but lithium precipitated on the metal layer forms dendrites which degrade lifetime and safety
Solution Approach 1:
The negative electrode active material layer combines lithium metal (or lithium alloy) with graphitized platelet carbon nanofibers in a composite structure. The carbon nanofibers serve as a protective matrix that constrains lithium precipitation, preventing dendrite formation while allowing the lithium metal component to maintain high energy density.
Solution Approach 2:
The graphitized platelet carbon nanofibers are distributed throughout the negative electrode active material layer to create localized protective zones. These nanofibers provide structurally sound pathways for lithium ion deposition, ensuring that lithium precipitates uniformly along the carbon nanofiber network rather than forming dangerous dendrites, while preserving the high capacity of the lithium metal.
3Reliability
If an end plate applying high external pressure is used to prevent pore generation, then battery operation reliability is improved, but the volume of the battery is excessively increased which reduces energy density
Solution Approach 1:
The invention extracts the pore-prevention function from the external end plate mechanism and integrates it directly into the negative electrode active material layer. By incorporating graphitized platelet carbon nanofibers within the layer itself, the structure inherently prevents pore formation between the solid electrolyte and metal layer without requiring additional external pressure-applying components, thus maintaining high energy density.
Solution Approach 2:
The graphitized platelet carbon nanofibers act as an intermediary material between the solid electrolyte and the metal layer. These nanofibers fill and seal the pores that would otherwise form at the interface, mediating the contact between electrolyte and metal to ensure reliable operation without requiring external mechanical pressure from end plates.
4Productivity
If a high amount of silver nanoparticles is used in the negative electrode active material layer to enhance lithium ion storage, then initial charge/discharge efficiency is improved, but the price competitiveness of the battery is reduced
Solution Approach 1:
The invention optimizes the concentration parameter of silver nanoparticles in the negative electrode active material layer. By carefully controlling the amount of silver nanoparticles to a minimal effective level and relying on the graphitized platelet carbon nanofibers for the majority of lithium ion storage capacity, the battery achieves satisfactory initial charge/discharge efficiency while significantly reducing material costs and improving price competitiveness.
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 use of graphitized platelet carbon nanofibers and silver nanoparticles improves lithium ion mobility, reduces irreversible capacity, and enhances the initial charge/discharge efficiency and life characteristics of the battery, while minimizing energy density loss and maintaining mechanical strength, thus addressing safety and efficiency concerns.
Implementation Method 1
forming dry mixed powder including graphitized platelet carbon nanofibers and silver nanoparticles disposed on the graphitized platelet carbon nanofibers by reducing silver ions in a mixture of the silver ions and the graphitized platelet carbon nanofibers
Implementation Method 2
lithium ions are reduced and precipitated by the negative electrode active material layer during charge
Implementation Method 3
lithium ions are reduced and precipitated by the negative electrode active material layer during charge
Implementation Method 4
the stored lithium may be dissolved in the form of lithium ions during discharge, and thus, the lithium ions may move to a positive electrode
Data Source
AI summary
An all-solid lithium secondary battery and a preparation method thereof are proved. The all-solid lithium secondary battery comprises a positive electrode active material layer, a negative electrode active material layer including graphitized platelet carbon nanofibers and silver nanoparticles, and a solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer.