Nb-Coated Cathode Material for Solid-State Battery Interface Resistance
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Solution Overview
Problem
Existing solid-state lithium batteries do not adequately achieve high output characteristics and voltage endurance due to the formation of high resistance layers at the contact interface between the solid electrolyte and the positive electrode active material.
Innovation Solution
A coated positive electrode active material for lithium secondary batteries is developed, featuring a niobium-containing coating layer with a specific local structure, as characterized by X-ray absorption fine structure spectroscopy (XAFS). The coating layer has a controlled arrangement of niobium and oxygen atoms, with a preferred energy difference between certain absorption peaks indicating improved ion conductivity and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an amorphous lithium ion-conductive oxide layer including Li and Nb is interposed between a positive electrode active material and a solid electrolyte layer, then formation of a high resistance layer at the contact interface is inhibited, but it is difficult to simultaneously achieve both desirable high output characteristics and desired voltage endurance characteristics
Solution Approach 1:
The invention changes the local structural parameters of the Nb-containing coating layer by controlling the difference in absorption energy at peak tops in the XAFS spectrum (12.9 eV or greater). This parameter change optimizes the arrangement of atoms in the coating layer, enabling simultaneous achievement of high output characteristics and voltage endurance characteristics that cannot be achieved with conventional amorphous LiNbO3 coatings alone.
Solution Approach 2:
The invention creates a composite coating layer that combines Nb-containing compounds with specific local structures. This composite structure, characterized by the controlled XAFS spectral features, integrates the benefits of lithium ion conductivity with enhanced structural stability and optimized electrochemical performance, resolving the contradiction between power and reliability.
2Use of energy by moving object
If a solid-state battery is designed to achieve high energy density, then energy storage capacity is improved, but formation of a high resistance layer at the contact interface between solid electrolyte and positive electrode active material occurs, reducing output characteristics
Solution Approach 1:
The Nb-containing coating layer acts as an intermediary between the solid electrolyte and the positive electrode active material. This intermediate layer prevents direct contact between the electrolyte and active material, inhibiting formation of high resistance layers while maintaining high lithium ion conductivity. The coating layer's specific local structure (characterized by XAFS peak energy difference ≥12.9 eV) optimizes this mediating function, enabling simultaneous achievement of high energy density and output characteristics.
3Reliability
If the positive electrode active material surface is covered with a lithium-ion conductive oxide to improve interface contact, then voltage endurance is enhanced, but output characteristics remain insufficient
Solution Approach 1:
The invention modifies the physical and chemical parameters of the coating layer by controlling the local atomic arrangement around Nb atoms, as evidenced by the XAFS spectral characteristics (peak energy difference ≥12.9 eV). This parameter optimization enhances both lithium ion conductivity and electronic conductivity at the interface, enabling the coating to simultaneously improve voltage endurance and output characteristics rather than just one or the other.
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 coated positive electrode active material enhances both output characteristics and voltage endurance in lithium secondary batteries, maintaining high performance and capacity retention even after repeated charging and discharging cycles.
Implementation Method 1
a coating layer that is disposed on a surface of the positive electrode active material and includes niobium atoms... the lithium-ion conductive oxide is mainly formed of sulfide... the lithium-ion conductive oxide is preferably in an amorphous state
Implementation Method 2
When peaks observed at a niobium (Nb)—L3 absorption edge of an X-ray absorption fine structure spectrum of the coated positive electrode active material measured by X-ray absorption fine structure spectroscopy (XAFS)
Data Source
AI summary
A coated positive electrode active material for lithium secondary batteries includes a positive electrode active material, and a coating layer disposed on a surface of the positive electrode active material. The coating layer includes niobium atoms. When peaks observed at a niobium (Nb)—L3 absorption edge of an X-ray absorption fine structure spectrum of the coated positive electrode active material measured by X-ray absorption fine structure spectroscopy (XAFS) are designated as a peak A, a peak B, and a peak C in an order from lower absorption energy, a difference between absorption energy at a peak top of the peak A and absorption energy at a peak top of the peak C is 12.9 eV or greater.