Solid-State Battery Anode Surface Tuning for Low-Pressure Durability
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Solution Overview
Problem
The large volume change of silicon (Si) during charge and discharge in all solid state batteries leads to degradation of ion and electron conducting paths, resulting in poor capacity durability, especially when low restraining pressure is applied.
Innovation Solution
Incorporating a silicon clathrate II type crystal phase as the anode active material and adjusting its specific surface area to between 8 m2/g and 17 m2/g, while applying restraining pressure of 0 MPa to 5 MPa, enhances the capacity durability of the all solid state battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high restraining pressure is applied to the battery to secure ion and electron conducting paths, then capacity durability is improved, but device complexity increases due to requirement of restraining jig
Solution Approach 1:
The patent changes the physical and chemical parameters of the anode active material by specifying a particular specific surface area range (8-17 m2/g) and crystal structure characteristics. This parameter optimization allows the material to maintain structural stability during charge-discharge cycles without requiring external restraining pressure, thereby improving capacity durability while eliminating the need for complex restraining jigs
Solution Approach 2:
The anode active material is designed to self-maintain its structural integrity and conducting paths through its optimized specific surface area and crystal phase characteristics. The material inherently resists volume expansion damage without external assistance, making the system self-sufficient and eliminating the need for additional restraining devices
2Use of energy by moving object
If Si-based active material is used to achieve high energy density, then energy density is improved, but volume change during charge and discharge increases leading to path cutoff and capacity degradation
Solution Approach 1:
The patent optimizes the specific surface area parameter of the Si-based anode active material to a specific range (8-17 m2/g) and controls its crystal phase composition. These parameter changes enable the material to accommodate volume expansion during lithiation while maintaining structural integrity and conducting paths, thus achieving both high energy density and good capacity durability
Solution Approach 2:
The anode active material is designed as a composite structure with specific crystal phase composition and controlled surface properties. This composite approach combines the high capacity advantage of Si with structural stability features, allowing the material to withstand volume changes during charge-discharge cycles without losing conducting paths
Data Source
AI summary
A main object of the present disclosure is to provide a car having an all solid state battery with excellent capacity durability when restraining pressure is not applied or even when low restraining pressure is applied thereto. The present disclosure achieves the object by providing an all solid state battery comprising layers in the order of a cathode layer, a solid electrolyte layer, and an anode layer; wherein the anode layer contains an anode active material including a silicon clathrate II type crystal phase; restraining pressure of 0 MPa or more and less than 5 MPa is applied to the all solid state battery in a layering direction; and a specific surface area of the anode active material is 8 m2/g or more and 17 m2/g or less.