All-Solid-State Battery Electrode Balance for Dendrite Suppression
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Solution Overview
Problem
Lithium batteries with solid electrolytes face challenges such as disconnected ion conduction paths, increased internal resistance, and growth of lithium dendrites due to volume changes in cathode active materials, leading to reduced safety and performance.
Innovation Solution
An all-solid secondary battery design incorporating a cathode layer, anode layer, and a solid electrolyte layer with a first two-dimensional sulfide-based solid electrolyte, where the anode active material layer has an initial charge capacity less than 50% of the cathode active material layer, to enhance ion conduction and suppress dendrite growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solid electrolyte particles with aspect ratio less than 2 are used, then the battery structure is simple and easy to manufacture, but the ion conduction path becomes disconnected during charging/discharging due to volume changes
Solution Approach 1:
The patent employs a binder material that dynamically adapts to volume changes of the cathode active material during charging and discharging. The binder maintains flexible contact with the solid electrolyte particles, allowing the ion conduction path to remain continuous despite the expansion and contraction of the cathode material. This dynamic adaptation resolves the contradiction between using simple solid electrolyte particles and maintaining reliable ion conduction.
Solution Approach 2:
The binder acts as an intermediary between the cathode active material and the solid electrolyte particles. It compensates for the volume changes of the cathode material and maintains stable contact with the solid electrolyte, preventing disconnection of the ion conduction path. This intermediary role allows the use of simple solid electrolyte particles while ensuring continuous ion conduction.
2Ease of manufacture
If solid electrolyte particles with aspect ratio less than 2 are used, then manufacturing is easier, but internal resistance increases due to disconnected ion conduction paths
Solution Approach 1:
The dynamic binder material adapts to volume changes during battery operation, maintaining continuous contact with solid electrolyte particles. This ensures stable ion conduction paths and consistent internal resistance characteristics, resolving the contradiction between ease of manufacture and internal resistance control.
Solution Approach 2:
The binder serves as an intermediary that stabilizes the interface between cathode active material and solid electrolyte particles. By maintaining reliable contact despite volume changes, it ensures consistent ion conduction and controlled internal resistance, enabling the use of easily manufactured solid electrolyte particles.
3Reliability
If solid electrolyte layer is used, then ionic conductivity is improved, but lithium dendrite growth is suppressed less effectively compared to liquid electrolyte
Solution Approach 1:
The patent applies different materials with specific local functions: the solid electrolyte provides high ionic conductivity in its local region, while the binder material locally accommodates volume changes and prevents dendrite formation at the interface. This local differentiation of functions resolves the contradiction between ionic conductivity and dendrite suppression.
Solution Approach 2:
The cathode layer forms a composite structure combining solid electrolyte particles with binder material. This composite achieves both high ionic conductivity from the solid electrolyte and effective dendrite suppression through the binder's ability to accommodate volume changes and maintain stable interfaces.
4Object-affected harmful factors
If the anode active material layer capacity is made less than 50% of cathode capacity, then lithium dendrite growth is suppressed, but the battery energy density is reduced
Solution Approach 1:
The binder material performs preliminary anti-action by preventing volume change-induced disconnection and interface degradation. This allows the anode capacity to be limited below 50% of cathode capacity without causing dendrite growth, as the binder proactively prevents the conditions that would lead to dendrite formation even at low anode capacities.
Solution Approach 2:
The binder acts as an intermediary that decouples the relationship between anode capacity and dendrite growth. By maintaining stable interfaces and accommodating volume changes, it allows the system to operate with limited anode capacity (below 50% of cathode) while still suppressing dendrite growth through the binder's protective function rather than relying solely on capacity balancing.
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 battery design effectively suppresses short circuits, improves cycle characteristics, and enhances high-rate and output characteristics by maintaining ion conduction paths and accommodating volume changes in the cathode active material.
Implementation Method 1
a solid electrolyte layer disposed between the cathode layer and the anode layer
Implementation Method 2
accommodating volume changes in the cathode active material
Data Source
Figure 1~3
Figure 4~5c
Figure 6~8
AI summary
This all-solid state secondary battery comprises a positive electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein: the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, at least one of the positive electrode active material layer and the solid electrolyte layer comprises a first two-dimensional sulfide-based solid electrolyte; the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer disposed on at least one surface of the negative electrode current collector; and the initial charge capacity (B) of the first negative electrode active material layer is less than about 50% of the initial charge capacity (A) of the positive electrode active material layer.