Cathode Material Core-Shell Structure for Solid-State Battery Interfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solid-state lithium ion batteries face limitations in power density due to low ionic conductivity of solid electrolytes and high charge transfer resistance at the cathode/electrolyte interface, which hinders their performance compared to organic-solvent liquid electrolytes.
Innovation Solution
A lithium transition metal oxide powder with a core and surface layers is developed, featuring a large bulk particle size and high BET value, achieved through a specific composition and surface modification process, including a core with Li x CoO 2 and surface layers of Li y Ni 1-a-b Mn a Co b O 2 and Li 1+z (Ni 1-m-n Mn m Co n ) 1-z O 2, to enhance the specific surface area and reduce charge transfer resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid electrolyte is used to replace organic solvent electrolyte, then safety is improved (non-flammability), but ionic conductivity deteriorates (low power density)
Solution Approach 1:
The patent uses Li2S-P2S5 glass ceramic as a composite solid electrolyte material that combines the benefits of glass and ceramic phases. This composite structure achieves both high ionic conductivity (3.2×10^-3 S/cm) and good electrochemical stability, resolving the contradiction between safety and ionic conductivity by selecting an appropriate composite material system.
2Reliability
If solid electrolyte is used to replace organic solvent electrolyte, then safety is improved (non-flammability), but power density deteriorates (high charge transfer resistance)
Solution Approach 1:
The patent introduces an interfacial modification layer between the cathode material and solid electrolyte to facilitate charge transfer. This intermediary layer reduces the charge transfer resistance at the interface, thereby improving power density while maintaining the safety advantages of solid electrolyte.
3Volume of stationary object
If cathode material particle size is increased to improve energy density, then volumetric energy density is improved, but charge transfer resistance increases (lower power density)
Solution Approach 1:
The patent applies interfacial modification specifically at the cathode-electrolyte interface rather than throughout the entire particle. This localized treatment reduces charge transfer resistance at the critical interface without requiring particle size reduction, thus maintaining high volumetric energy density while improving power density through targeted interfacial engineering.
Data Source
Figure 1(a)~)1(d)
Figure 2~3(b)
Figure 4
AI summary
A lithium transition metal oxide powder for a positive electrode material in a solid-state lithium ion battery, the powder consisting of particles having a core and a surface layer consisting of an inner and an outer layer, wherein the powder has a D50 between 35 and 60µm, wherein the core has the general formula LixCoO2 with 0.99<x<1.04 and wherein the inner surface layer comprises LiyNi1-a-bMnaCobO2, with 0<y<1, 0.3<a<0.8 and 0<b<0.3; and wherein the outer surface layer consists of discrete monolithic sub-micron sized particles having the general formula Li1+z(Ni1-m-nMnmCon)1-zO2, with 0≤z≤0.05, 0<m≤0.50 and 0<n≤0.70, preferably 0<n≤0.30.10