Composite Solid Electrolyte Structure for Lithium Short-Circuit Prevention
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Solution Overview
Problem
Lithium batteries face the challenge of short circuiting due to lithium growth during charging, which existing solid electrolytes fail to prevent effectively, despite exhibiting high critical current density.
Innovation Solution
A composite structure for lithium batteries is developed, comprising a compact layer and a porous layer made of garnet oxide with a sintering aid, where the porous layer has a relative density between 40% and 60% and is integrally formed with the compact layer without a bonding interface, preventing short circuiting while maintaining ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte with high critical current density is used, then ion conductivity is improved, but short circuiting occurs due to lithium growth during charging
Solution Approach 1:
The solid electrolyte is segmented into two distinct layers: a compact layer (90% or higher density) for preventing lithium growth and short circuiting, and a porous layer (50% or higher porosity) for accommodating lithium expansion during charging. This segmentation allows each layer to specialize in its function, resolving the contradiction between ion conductivity and short circuiting prevention.
Solution Approach 2:
Different regions of the solid electrolyte are given different properties: the compact layer has high density and low porosity to prevent lithium penetration and short circuits, while the porous layer has high porosity to accommodate lithium volume changes. This local differentiation of properties allows the system to simultaneously achieve short circuiting prevention and ion conductivity.
2Reliability
If grain boundaries are modified with Li2CO3 and LiOH to achieve higher critical current density, then ion conductivity is improved, but lithium grows via voids causing short circuiting
Solution Approach 1:
The electrolyte is divided into compact and porous layers, where the compact layer prevents lithium growth through its dense structure, while the porous layer provides a controlled environment for lithium accommodation. This segmentation prevents the harmful effect of uncontrolled lithium growth through voids while maintaining high critical current density.
Solution Approach 2:
The porous layer acts as an intermediary between the electrodes and the compact layer, providing a buffer zone that accommodates lithium volume changes and prevents direct contact between lithium and the compact layer, thereby preventing short circuits while maintaining ion conductivity.
3Object-affected harmful factors
If a dense compact layer is formed to prevent short circuiting, then short circuiting is prevented, but ion conductivity decreases
Solution Approach 1:
The electrolyte is segmented into a compact layer for short circuiting prevention and a porous layer for maintaining ion conductivity. The compact layer (90%+ density) prevents lithium penetration, while the porous layer (50%+ porosity) ensures high ion conductivity, resolving the contradiction between these two requirements.
Solution Approach 2:
The solid electrolyte is constructed as a composite structure combining a compact layer and a porous layer, each with optimized density and porosity characteristics. This composite structure allows the system to simultaneously achieve short circuiting prevention (via the compact layer) and high ion conductivity (via the porous layer).
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 composite structure effectively prevents internal short circuiting and enhances lithium ion conductivity, ensuring stable battery performance by securing a precipitation field in the porous layer and forming a compact layer to prevent short circuiting.
Implementation Method 1
when a precipitation field in which a metal is precipitated is secured in a porous layer
Implementation Method 2
a compact layer for preventing short circuiting is integrally formed
Implementation Method 3
a composite structure... made of a solid electrolyte and a porous layer which contains the solid electrolyte and is integrally formed with the compact layer... wherein at least one of the compact layer and the porous layer contains a sintering aid
Data Source
Figure 1
Figure 2A~2D
Figure 3~4
AI summary
A composite structure is adapted to a separator (20) of a secondary battery, and includes a compact layer (21) containing a solid electrolyte and a porous layer (22) which contains a solid electrolyte and is integrally formed with the compact layer (21) without having a bonding interface.