MIEC-Coated Battery Electrodes for Stable Solid-State Interfaces
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Solution Overview
Problem
All solid-state lithium-ion batteries face challenges in achieving good solid-solid contacts at the electrode-electrolyte interface, leading to increased cell impedance and decreased energy density due to insulating byproducts and the need for high-temperature sintering, which causes side reactions and reduces energy density.
Innovation Solution
Formation of mixed ionic and electronic conducting (MIEC) interface layers through doping or coating active material particles with lithiated metal oxides, phosphates, or sulfides during sintering to stabilize the interface and enhance ion and electron transfer, reducing the need for solid electrolyte and electronic conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature sintering is used to achieve good solid-solid contacts at the electrode-electrolyte interface, then contact quality improves, but side reactions occur and energy density decreases
Solution Approach 1:
A thin interfacial layer is introduced between the electrode and solid electrolyte to mediate the interaction. This interfacial layer prevents direct contact between reactive materials, suppressing side reactions during sintering while maintaining good solid-solid contacts for ion and electron transport.
Solution Approach 2:
The sintering temperature and atmosphere parameters are optimized to enable good contact formation without reaching conditions that trigger harmful side reactions. By controlling the sintering process parameters, the patent achieves reliable interfaces while preserving energy density.
2Reliability
If solid electrolyte particles are used to ensure ionic conduction, then ionic conductivity improves, but device complexity increases due to interface contact issues
Solution Approach 1:
The patent merges the electrode and solid electrolyte into a composite structure with intimate physical contact. By combining these components at the particle level rather than as separate layers, the design simplifies the interface while ensuring continuous ionic conduction pathways.
Solution Approach 2:
The interfacial region is given special properties through the introduction of a thin interfacial layer that is different from the bulk materials. This local modification ensures good contact quality and ionic conductivity at the critical interface without affecting the overall device structure.
3Stability of the object's composition
If insulating byproducts form at the electrode-electrolyte interface, then interface stability worsens, but impedance increases
Solution Approach 1:
The patent converts the potentially harmful effect of byproduct formation into a beneficial outcome by designing an interfacial layer that either prevents byproduct formation or transforms insulating byproducts into conductive phases. The interfacial layer acts as a buffer that manages reaction products favorably.
Solution Approach 2:
The interfacial layer serves as a mediator that prevents direct interaction between electrode and solid electrolyte materials, thereby preventing the formation of insulating byproducts. This intermediary layer maintains both interface stability and low impedance by controlling the chemical environment at the interface.
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 MIEC layers improve energy density by stabilizing the interface, reducing impedance, and increasing the energy density by up to 35% compared to composite electrodes with 30-50% electrolyte content, while maintaining stable battery performance.
Implementation Method 1
diffusion of dopant within the solid electrolyte particles or active material particles toward a surface of the active material particles
Implementation Method 2
reaction of the dopant with the solid electrolyte particles
Implementation Method 3
The solid electrolyte particles may be sintered with the active material particles
Implementation Method 4
The mixed ionic and electronic conducting conformal interface layer results from reaction of layers of metal oxide, metal phosphate, metal silicate, or metal sulfide with the active material particles during bonding
Data Source
AI summary
A solid-state battery includes an anode, a cathode, and a solid electrolyte between the anode and cathode. The anode or cathode includes bonded active material particles having thereon a mixed ionic and electronic conducting conformal interface layer that provides a transport path for ions and electrons during operation of the solid-state battery, and lacks solid electrolyte particles.