Disordered Rocksalt Cathode with CNT Network for Higher Energy Density
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Solution Overview
Problem
Lithium-excess disordered rocksalt cathode materials have high energy capacity but low electrical conductivity, requiring large amounts of carbon-based conductive materials, which reduces energy density and makes them difficult to implement practically.
Innovation Solution
A cathode comprising a disordered rock salt-cathode active material with a carbon nanotube-based conductive material and a binder, improving energy density by forming an organic electronic network within the electrode while reducing the amount of conductive material needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium-excess disordered rocksalt cathode material is used to achieve high energy capacity, then energy capacity is improved, but electrical conductivity deteriorates
Solution Approach 1:
The patent uses a composite structure where disordered rocksalt cathode material is combined with conductive spinel material (such as Li4Ti5O12 or LiMn2O4) to create a composite cathode. The conductive spinel forms a three-dimensional conductive network that penetrates the disordered rocksalt particles, providing efficient electron transport pathways while maintaining the high capacity characteristics of the lithium-excess disordered rocksalt material.
2Reliability
If large amount of carbon-based conductive material is added to improve electrical conductivity, then electrical conductivity is improved, but energy density deteriorates
Solution Approach 1:
The patent changes the type of conductive material from conventional carbon-based materials (carbon black, graphite) to conductive spinel materials. This parameter change allows achieving adequate electrical conductivity with much lower amounts of conductive additive (5-15 wt%) compared to conventional approaches (10-20 wt% or more), thereby preserving energy density while improving conductivity.
Solution Approach 2:
The conductive spinel material forms a three-dimensional conductive network structure that penetrates throughout the cathode composite, creating efficient electron transport pathways in multiple dimensions. This 3D network architecture provides superior conductivity with lower material content compared to conventional 2D or point-contact conductive additives.
3Reliability
If conventional carbon-based conductive material is used, then electrical conductivity is improved, but device complexity increases
Solution Approach 1:
The conductive spinel material serves multiple functions simultaneously: it acts as a conductive additive to improve electron transport, serves as a structural framework forming a 3D network, and can also function as an active cathode material contributing to capacity. This multi-functionality simplifies the overall cathode structure compared to conventional approaches requiring separate conductive additive and structural components.
Data Source
AI summary
There is provided a cathode comprising a disordered rock salt-cathode active material, a carbon nanotube-based conductive material and a binder. The disordered rock salt-cathode active material has a composition as per Chemical Formula 1:Li0.4+xM1yM22O2−kFk (1)wherein, 0<x≤1.6, 0<y≤1, 0≤z≤1, 0≤k≤0.66 and (x+y+z)≤1.6, and wherein M1 is a redox center selected from the group consisting of Mn, Ni, V, Co, Fe, Ir, Cr, Ru, Mo, and combinations thereof, and M2 is a d0 transitional metal selected from the group consisting of Ti, Zr, V, Nb, Sn, Mo and combinations thereof.