Lithium Ion Battery with Glass-Ceramic Electrolyte and Buffer Layer
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Solution Overview
Problem
Lithium ion batteries face limitations due to low energy density and volatility, which are exacerbated by the decomposition of lithium ion conductive glass-ceramic electrolytes when exposed to conventional negative active materials.
Innovation Solution
Incorporating a buffer layer with secondary negative active materials having a redox potential greater than the lithium ion conductive glass-ceramic, and using a solid lithium ion conductive glass-ceramic electrolyte that operates as a separator, eliminating the need for a traditional separator and reducing the weight of the battery by using non-metallic case materials like epoxy, which are compatible with the glass-ceramic electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional negative active materials (lithium metal, lithiated carbon, lithium alloys) are used with lithium ion conductive glass-ceramic electrolyte, then the battery can achieve high energy density, but the glass-ceramic electrolyte decomposes due to reduction reactions
Solution Approach 1:
A buffer layer comprising lithium titanium oxide (LTO) particles is introduced as an intermediary between the conventional negative active materials and the lithium ion conductive glass-ceramic electrolyte. The LTO buffer layer has a redox potential greater than the glass-ceramic electrolyte, preventing reduction reactions and electrolyte decomposition while allowing lithium ion transport. This mediator resolves the contradiction by enabling high energy density materials to coexist with stable glass-ceramic electrolyte.
Solution Approach 2:
The negative electrode is designed as a composite structure combining conventional negative active materials (providing high energy density) with lithium titanium oxide buffer layer particles (providing electrochemical stability). This composite approach allows the battery to achieve both high energy density and electrolyte stability by combining materials with complementary properties.
2Use of energy by moving object
If a traditional separator is used in the battery, then the battery structure is complete, but the battery weight increases and energy density decreases
Solution Approach 1:
The lithium ion conductive glass-ceramic electrolyte is designed to perform multiple functions simultaneously: it serves as the ionic conductor enabling lithium ion transport and also functions as the separator preventing direct contact between positive and negative electrodes. This multi-functionality eliminates the need for a separate traditional separator, reducing battery weight and increasing gravimetric energy density while maintaining complete battery structure.
3Device complexity
If lithium ion conductive glass-ceramic electrolyte is used without buffer layer, then the battery structure is simpler, but the electrolyte volatility increases due to decomposition
Solution Approach 1:
The lithium titanium oxide buffer layer acts as a protective intermediary between the negative electrode and glass-ceramic electrolyte, preventing decomposition reactions that would increase electrolyte volatility. The buffer layer's higher redox potential creates a stable interface, eliminating harmful reduction reactions while adding minimal structural complexity.
4Strength
If metal case materials are used in the battery, then the battery has high structural strength, but the battery weight increases
Solution Approach 1:
The battery case material is changed from traditional metals to non-metallic materials such as epoxy, which are compatible with the glass-ceramic electrolyte. This parameter change in material composition reduces battery weight while the glass-ceramic electrolyte's inherent stability provides the necessary structural integrity and chemical compatibility, eliminating the need for heavy metal containment.
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
This configuration enhances the gravimetric energy density of the battery, increases safety by reducing volatility, and eliminates the need for safety valves and current interruption devices, achieving a lithium ion battery with a gravimetric energy density higher than 580 w-hr/kg while maintaining the advantages of traditional negative active materials.
Implementation Method 1
The electrolyte is a solid including a lithium ion conductive glass-ceramic
Implementation Method 2
The buffer layer includes one or more secondary negative active materials that do not cause a decomposition reaction with the lithium ion conductive glass-ceramic. For instance, one or more secondary negative active materials can have a redox potential that exceeds the redox potential of the lithium ion conductive glass-ceramic.
Data Source
AI summary
The battery includes a solid electrolyte activating a positive electrode and a negative electrode. The electrolyte is a solid including a lithium ion conductive glass-ceramic. The negative electrode includes a buffer layer between a negative medium and the electrolyte. The negative medium includes one or more primary negative active materials. The buffer layer includes one or more secondary negative active materials that do not dissolve the lithium ion conductive glass-ceramic. The secondary negative active materials can have a redox potential greater than 0.5 V vs Li/Li+.