Solid-State Sodium-Ion Battery With Third Electrode Replenishment
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Solution Overview
Problem
Rocking chair all-solid-state sodium-ion secondary batteries face issues with insufficient initial charge-discharge efficiency and deteriorating cycle characteristics due to sodium ion trapping and capacity loss during repeated charge and discharge.
Innovation Solution
Incorporating a third electrode capable of releasing sodium ions, connected to the solid electrolyte layer, which replenishes sodium ions to the positive electrode, and serving as a reference electrode for deterioration diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rocking chair battery structure is used with sodium-ion conductive oxide solid electrolyte, then the battery can operate with solid electrolyte instead of organic electrolyte, but the initial charge-discharge efficiency is insufficient and cycle characteristics deteriorate
Solution Approach 1:
The invention divides the battery structure into three electrode layers (positive electrode, negative electrode, and third electrode) with the solid electrolyte layer positioned between them. This segmentation allows the third electrode to specifically address sodium ion replenishment needs without interfering with the primary charge-discharge reactions between the positive and negative electrodes, thereby improving both initial efficiency and cycle characteristics
Solution Approach 2:
The third electrode acts as an intermediary component that facilitates sodium ion replenishment to the solid electrolyte layer during charging. This intermediary structure resolves the contradiction by providing a dedicated pathway for sodium ion supply that enhances charge-discharge efficiency without compromising the solid electrolyte's structural integrity or cycle stability
2Object-affected harmful factors
If oxide-based solid electrolyte is used instead of organic electrolytic solution, then safety concerns about burning or explosion are reduced, but ionic conductivity is low and high power operation becomes difficult
Solution Approach 1:
The invention changes the operational parameters of the solid electrolyte by introducing the third electrode that actively replenishes sodium ions. This parameter change (sodium ion concentration maintenance) enables the solid electrolyte to achieve both high safety (inherent property) and improved ionic conductivity (through active management), resolving the contradiction between safety and power
3Productivity
If repeated charge and discharge cycles are performed, then battery capacity is utilized, but sodium ions are trapped and capacity is lost
Solution Approach 1:
The third electrode enables continuous sodium ion replenishment to the solid electrolyte layer throughout repeated charge-discharge cycles. This continuous action prevents sodium ion trapping and capacity loss, allowing the battery to maintain high capacity utilization over extended cycling without the substance loss that plagues conventional rocking chair batteries
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
Enhances initial charge-discharge efficiency and maintains capacity after repeated cycles by reducing irreversible capacity and allowing sodium ion replenishment, while enabling battery deterioration diagnosis.
Implementation Method 1
a solid electrolyte layer (2) having a first principal surface (2a) and a second principal surface (2b) opposed to each other and being made of a sodium-ion conductive oxide
Implementation Method 2
a third electrode (7, 27) connected to the solid electrolyte layer (2) and containing a metal capable of releasing sodium ions
Data Source
Figure 1~2
Figure 3~4
AI summary
Provided is an all-solid-state sodium-ion secondary battery that can increase the initial charge-discharge efficiency and the capacity after repeated charge and discharge. An all-solid-state sodium-ion secondary battery 1 includes: a solid electrolyte layer 2 having a first principal surface 2a and a second principal surface 2b opposed to each other and being made of a sodium-ion conductive oxide; a positive electrode layer 3 provided on the first principal surface 2a of the solid electrolyte layer 2; a negative electrode layer 4 provided on the second principal surface 2b of the solid electrolyte layer 2; and a third electrode 7 connected to the solid electrolyte layer 2 and containing a metal capable of releasing sodium ions.