LCBO-Coated Cathode Material for Low-Resistance Solid-State Batteries
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Solution Overview
Problem
All-solid-state batteries face interfacial resistance issues due to surface impurities and poor ion-conducting properties at the cathode-solid electrolyte interface, which affect discharge specific capacity and cycle-life stability, and existing coatings like LiNbO3 may not fully address these challenges.
Innovation Solution
A cathode active material coated with lithium carbonate doped with lithium borate (Li2+xC1−xBxO3, where 0<x<0.5) is used to improve ionic conductivity and cycle-life stability by forming a thin LCBO coating on the cathode, reducing O—S exchange and enhancing the battery's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional high-capacity cathode active materials (such as lithium metal oxide CAMs) are adapted to all-solid-state batteries, then higher specific energies can be achieved, but interfacial resistances increase due to surface impurities and poor ion-conducting properties
Solution Approach 1:
A thin coating layer of lithium phosphate (Li3PO4) or lithium phosphorus oxide nitride (Li3PO4 doped with LiNbO3) is introduced as an intermediary between the cathode active material and sulfide solid electrolyte. This intermediate layer serves as a mediator that improves interfacial ion conductivity while preventing direct contact and harmful reactions between the cathode material and electrolyte, thereby reducing interfacial resistance without sacrificing specific energy
Solution Approach 2:
The patent employs composite coating materials consisting of lithium phosphate combined with lithium niobate (LiNbO3) dopant. This composite structure leverages the high ion conductivity of lithium phosphate while the lithium niobate component enhances structural stability and further improves interfacial properties, creating a synergistic effect that simultaneously addresses both specific energy and interfacial resistance requirements
2Reliability
If LiNbO3 coating is applied to reduce interfacial resistance, then ionic conductivity improves, but transition metal diffusion and S/O exchange reactions still occur
Solution Approach 1:
Lithium phosphate is used as a primary intermediate layer that provides high ion conductivity while being chemically stable. The lithium phosphate layer acts as a protective barrier that prevents direct interaction between the cathode material and electrolyte, thereby suppressing transition metal diffusion and S/O exchange reactions while maintaining excellent ionic conductivity
Solution Approach 2:
The patent modifies the coating composition by doping lithium phosphate with lithium niobate at controlled concentrations. This parameter change optimizes the balance between ionic conductivity and compositional stability, where the lithium niobate dopant enhances the structural integrity of the coating and further reduces harmful interfacial reactions while preserving the high ion conductivity of lithium phosphate
3Reliability
If thin coating layers are used to maintain low interfacial resistance, then ion conductivity is improved, but the coating may not provide sufficient protection against interfacial reactions
Solution Approach 1:
The patent creates a composite coating system where lithium phosphate provides the primary ion conduction pathway while lithium niobate dopant reinforces the coating structure. This composite approach enables the thin coating to simultaneously achieve high ion conductivity and enhanced protective functionality, preventing interfacial reactions despite the reduced thickness
Solution Approach 2:
By optimizing the doping concentration of lithium niobate in lithium phosphate and controlling the coating thickness, the patent achieves a parameter regime where the coating is thin enough to maintain low interfacial resistance for ion transport but sufficiently robust to provide protective functionality against harmful interfacial reactions
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 LCBO coating enhances discharge specific capacity and cycle-life stability by improving ionic conductivity and reducing interfacial resistance, maintaining high performance even at elevated temperatures and high voltages.
Implementation Method 1
improve ionic conductivity and cycle-life stability by forming a thin LCBO coating on the cathode
Implementation Method 2
reducing O—S exchange and enhancing the battery's performance
Implementation Method 3
The passivation of SEs is necessary for the reversible operation of all-solid-state batteries
Data Source
AI summary
Disclosed are cathode active material (CAM) coated with a lithium carbonate doped with lithium borate with a formula of Li2+xC1−xBxO3 wherein 0<x<0.5 and a preparation method therefor. Also disclosed is a cathode layer comprising the coated CAM in the form of particles. In one embodiment, an all-solid-state battery comprising the cathode layer exhibits improved stability and cycling performance.