All Solid State Battery Cathode Thickness Optimization
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Solution Overview
Problem
Current lithium batteries face challenges in achieving high energy density due to the use of flammable organic solvents, which require complex safety devices and impact production costs, while all-solid-state batteries with sulfide solid electrolytes aim to address these issues but need optimization for enhanced performance.
Innovation Solution
The all-solid-state battery system adjusts the actual thickness of the cathode active material layer based on its effective thickness, calculated using the effective Li ion conductivity and operation voltage width, to achieve a specific ratio that maximizes energy density, ensuring efficient Li ion movement and capacity utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the actual thickness of the cathode active material layer is increased to improve capacity, then the energy density improves, but the Li ion conductivity decreases due to longer ion transport path
Solution Approach 1:
The invention optimizes the thickness parameter of the cathode active material layer to a specific range (1-10 μm) to balance capacity and Li ion conductivity. By precisely controlling this geometric parameter, the patent achieves both high capacity utilization and maintained ion transport efficiency, resolving the contradiction between quantity of substance and reliability.
2Reliability
If the cathode active material layer is made thinner to improve Li ion conductivity, then the ion transport efficiency improves, but the capacity decreases due to less active material
Solution Approach 1:
The patent identifies and optimizes the thickness parameter within a specific range (1-10 μm) to simultaneously achieve high Li ion conductivity and adequate capacity. This parameter optimization allows the thin layer to maintain ion transport efficiency while containing sufficient active material for high capacity, resolving the contradiction between reliability and quantity of substance.
3Quantity of substance
If lithium batteries use liquid electrolytes with flammable organic solvents to achieve high energy density, then the energy density improves, but safety devices are required increasing device complexity
Solution Approach 1:
The invention transitions the electrolyte from liquid phase to solid phase by using a sulfide-based solid electrolyte layer. This phase transition eliminates the need for flammable organic solvents while maintaining high ionic conductivity, thereby achieving high energy density without requiring additional safety devices, resolving the contradiction between energy density and device complexity.
Solution Approach 2:
The solid electrolyte layer is designed to inherently provide safety functionality without requiring separate safety devices. The solid electrolyte itself acts as both the ionic conductor and the safety barrier, eliminating the need for additional complex safety systems while maintaining high energy density performance.
4Ease of manufacture
If the cathode active material layer thickness is not optimized relative to effective thickness, then manufacturing is simpler, but the performance of cathode active material and solid electrolyte cannot be sufficiently withdrawn
Solution Approach 1:
The patent establishes a specific thickness range (1-10 μm) for the cathode active material layer to ensure optimal performance utilization. This parameter specification provides clear manufacturing guidelines that balance ease of manufacture with maximum performance extraction, allowing standard fabrication processes to achieve the optimal thickness for high capacity and conductivity.
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 approach results in a battery system with improved energy density, simplifying safety measures and reducing production costs by optimizing the cathode active material and solid electrolyte performance within a defined thickness ratio.
Implementation Method 1
a solid electrolyte layer that is formed between the cathode active material layer and the anode active material layer
Implementation Method 2
κ′ represents effective Li ion conductivity (S/cm) of the cathode active material layer
Data Source
AI summary
Provided is an all solid state battery system with a high energy density. The all solid state battery system comprises an all solid state battery, and a discharging control unit that controls discharging of the all solid state battery, a cathode active material layer contains a cathode active material particle, and a sulfide solid electrolyte particle, and a ratio (T/t) of an actual thickness “T” of the cathode active material layer to an effective thickness “t” of the cathode active material layer which is calculated by the following Expression satisfies a relationship of 0.01≦T/t≦0.15;t=V/i×κ′(in which, V represents an operation voltage width (V), i represents a current density (mA/cm2) during discharging, and κ′ represents effective Li ion conductivity (S/cm) of the cathode active material layer).