Layered NMC Cathode Structure for Stable Sulfide SSB Cycling
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Solution Overview
Problem
Cathodes in sulfide-based solid-state batteries (SSBs) using nickel manganese cobalt (NMC) and lithium argyrodite (Li6PS5Cl) as the solid electrolyte face issues due to the formation of resistive interfacial layers, leading to capacity fading and reduced cycle life.
Innovation Solution
A cathode structure comprising two distinct layers: an ion transport layer with a homogeneous mixture of NMC and lithium argyrodite particles, coated with lithium ceramic to facilitate lithium-ion conduction, and an electron transport layer with a higher concentration of uncoated NMC particles and carbon additives to enhance electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon additives are added to enhance electrical conductivity, then electrical conductivity is improved, but capacity fade increases due to reaction with LPSC particles
Solution Approach 1:
The cathode is divided into two distinct layers: an electron transport layer with carbon additives for conductivity, and an ion transport layer without carbon additives to prevent harmful reactions with LPSC. This segmentation allows each layer to perform its specific function without the negative interactions that would occur in a mixed structure.
Solution Approach 2:
Different regions of the cathode are given different compositions tailored to their specific functions. The electron transport layer contains carbon additives for conductivity where needed, while the ion transport layer excludes carbon additives to prevent reactions with LPSC at the critical interface region.
2Use of energy by moving object
If NMC cathode is used with LPSC solid electrolyte, then energy density is improved, but resistive interfacial layers form causing capacity fading
Solution Approach 1:
The ion transport layer acts as an intermediary between the NMC cathode and LPSC solid electrolyte. This intermediate layer facilitates ion transport while preventing direct contact and harmful chemical reactions between NMC and LPSC, thereby maintaining both high energy density and capacity stability.
Solution Approach 2:
The harmful component (carbon additives) is extracted from the region where it causes problems (the ion transport layer in contact with LPSC), while being retained in the electron transport layer where it provides beneficial conductivity enhancement.
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 proposed cathode structure improves the energy density and output of solid-state batteries by facilitating efficient lithium-ion diffusion and maintaining stable electrical conductivity, thereby extending the cycle life and reducing capacity fade.
Implementation Method 1
coated with lithium ceramic to form an ion transport layer
Implementation Method 2
carbon additives have been considered to enhance conductivity
Implementation Method 3
sulfide-based solid-state batteries (SSBs) with nickel manganese cobalt (NMC)-based cathodes
Data Source
AI summary
A battery electrode for solid-state battery cells and a method for its fabrication are provided. The electrode comprises two layers, an ion transport layer comprising a homogeneous mixture of lithium argyrodite and lithium ceramic coated nickel manganese cobalt oxide particles, and an electron transport layer with uncoated nickel manganese cobalt oxide particles. The electron transport layer may include lithium argyrodite particles in a specific ratio and may be sulfide-based.