Single-Crystal Ni-Rich NMC Cathodes With Reduced Gassing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nickel-rich lithium-manganese-cobalt oxide (NMC) cathodes face challenges such as moisture sensitivity, aggressive side reactions, and gas generation during cycling, leading to safety concerns and cell degradation, particularly as the Ni content increases above 0.6, due to their aggregated particle structure and high surface area.
Innovation Solution
The development of methods to synthesize single crystalline lithium nickel manganese cobalt oxide with reduced surface areas and integrated crystal structures, using techniques like solid-state, molten-salt, and flash-sintering methods, which produce monocrystalline cathodes with reduced gassing and particle cracking during cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If aggregated particle structure with high surface area is used, then capacity is improved, but moisture sensitivity and side reactions increase
Solution Approach 1:
The cathode material is structured as hierarchical aggregates of primary particles, where each aggregate consists of multiple smaller particles (50-500 nm) clustered together. This segmentation maintains high surface area for capacity while the hierarchical structure reduces overall moisture sensitivity by creating a more controlled surface exposure.
Solution Approach 2:
The invention applies different characteristics to different levels of the hierarchical structure: primary particles have high surface area for electrochemical activity, while the aggregate level provides structural stability and reduced overall reactivity with moisture, creating local quality differences that resolve the contradiction.
2Quantity of substance
If aggregated particle structure with high surface area is used, then capacity is improved, but gas generation during cycling increases
Solution Approach 1:
By segmenting the cathode into hierarchical aggregates of primary particles, the structure provides sufficient surface area for high capacity while the aggregated configuration reduces gas generation during cycling through more stable structural configuration at the aggregate level.
Solution Approach 2:
The hierarchical aggregate structure creates a composite-like configuration where primary particles work together in a structured arrangement, combining the benefits of high surface area with reduced gas generation characteristics of more stable structures.
3Quantity of substance
If aggregated particle structure is used, then capacity is improved, but particle cracking during cycling increases
Solution Approach 1:
The hierarchical segmentation into primary particles and aggregates creates a structure where stress during cycling is distributed across multiple smaller units, reducing the likelihood of catastrophic cracking while maintaining high capacity through total surface area.
Solution Approach 2:
The nested hierarchical structure, where primary particles are nested within aggregates, allows for controlled deformation and stress distribution, preventing particle cracking while preserving the high capacity benefits of the aggregated configuration.
4Reliability
If monocrystalline structure is synthesized, then stability and reduced side reactions are achieved, but manufacturing complexity increases
Solution Approach 1:
The monocrystalline cathode material is synthesized as hierarchical aggregates of primary particles, where each particle maintains monocrystalline structure for stability, while the aggregate configuration simplifies the overall manufacturing process compared to creating large single crystals, reducing manufacturing complexity.
5Area of stationary object
If monocrystalline structure is synthesized, then reduced surface area is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The monocrystalline material is structured as hierarchical aggregates of primary particles (50-500 nm), where segmentation into controlled-size particles reduces total surface area compared to large single crystals, while the standardized particle size range simplifies manufacturing precision requirements through easier process control.
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 single crystalline NMC cathodes demonstrate improved stability and reduced side reactions, with enhanced cycling performance and capacity retention, addressing the safety and degradation issues associated with traditional polycrystalline NMC cathodes.
Implementation Method 1
heating a solid hydroxide precursor comprising NiXMnymCo1-x-y(OH)2 at a temperature TS1 in an oxygen-containing atmosphere for an effective period of time t1 to convert the solid hydroxide precursor to a solid oxide precursor
Implementation Method 2
heating the solid oxide precursor and the solid lithium compound at a temperature TS2 for an effective period of time t2 to produce a first product
Data Source
AI summary
Methods for synthesizing single crystalline Ni-rich cathode materials are disclosed. The Ni-rich cathode material may have a formula LiNiXMnyMzCo1-x-y-zO2, where M represents one or more dopant metals, x≥0.6, 0.01≤y<0.2, 0≤z≤0.05, and x+y+z≤1.0. The methods are cost-effective, and include methods for solid-state, molten-salt, and flash-sintering syntheses.