Boron-Coated Cathode Particles for Stable Sulfide Solid Electrolyte Interfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The interface reaction between sulfide-based solid electrolytes and positive electrode active materials in all-solid-state batteries leads to deteriorated electrochemical performance, particularly in charge/discharge characteristics, despite previous surface treatments.
Innovation Solution
A method involving thermal treatment of dried positive electrode active material particles with boron to form a high-ion conductivity LBO coating, such as LiBO2 and Li2B4O7, is applied to inhibit interface reactions, using a dry-mixing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cathode active material particles are used in sulfide-based all-solid batteries, then the battery can operate, but internal stress occurs during charge-discharge cycles leading to particle cracking and poor contact with solid electrolyte
Solution Approach 1:
The cathode active material particle is divided into a core region and a shell region. The core region contains the active material, while the shell region surrounds it and has a larger volume expansion coefficient. This segmentation allows each region to have specialized functions: the core maintains structural integrity while the shell accommodates volume changes, preventing particle cracking and maintaining contact with the solid electrolyte.
Solution Approach 2:
The cathode active material particle is constructed as a composite structure with a core-shell configuration. The core and shell are made of different materials with different expansion coefficients, creating a composite particle that combines the benefits of both materials: the core provides structural stability while the shell provides volume expansion accommodation, solving the contradiction between structural integrity and contact stability.
2Quantity of substance
If cathode active material particles with large volume expansion are used to achieve high capacity, then energy density improves, but particle cracking occurs due to internal stress during charge-discharge cycles
Solution Approach 1:
The particle is segmented into core and shell regions with different functions. The shell region is specifically designed to have a larger volume expansion coefficient to accommodate the volume changes during lithium ion insertion and extraction, while the core region maintains structural integrity. This segmentation allows high capacity operation without particle cracking.
Solution Approach 2:
The invention changes the volume expansion coefficient parameter by creating a shell region with a larger expansion coefficient than the core region. This parameter change allows the particle to accommodate large volume expansions during charge-discharge cycles without cracking, enabling high lithium ion capacity while maintaining structural integrity.
3Productivity
If conventional spherical cathode particles are used, then manufacturing is simple, but lithium ion diffusion distance is long leading to slow reaction kinetics
Solution Approach 1:
The particle is segmented into core and shell regions, which creates a more complex internal structure. However, this segmentation enables shorter lithium ion diffusion paths within the core region and provides additional reaction sites at the core-shell interface, improving lithium ion diffusion rate and reaction kinetics despite the increased structural complexity.
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 method enhances ion conductivity and improves charge/discharge characteristics, resulting in improved battery performance and capacity, with a simplified manufacturing process and reduced byproducts.
Implementation Method 1
having a larger volume expansion coefficient than the core region, wherein the volume expansion coefficient refers to a value representing a rate of change of volume during charge and discharge
Implementation Method 2
In a sulfide-based all-solid battery, a sulfide-based solid electrolyte is in direct contact with a cathode active material
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Disclosed herein is a new method of treating the surface of a positive electrode active material that is capable of inhibiting a reaction at the interface between a sulfide-based solid electrolyte and the positive electrode active material. An excellent positive electrode active material particle for sulfide-based all-solid-state batteries, the surface of which is reformed, using the method and a sulfide-based all-solid-state battery, the charge/discharge characteristics of which are improved, including the same are also disclosed. The positive electrode active material particle for sulfide-based all-solid-state batteries manufactured using the new dry-type method exhibits larger capacity than a positive electrode active material particle for sulfide-based all-solid-state batteries manufactured through a conventional wet-type process. In addition, the manufacturing process is simplified, and the amount of byproducts is reduced.