Mixed Transition Metal Oxide Cathodes for Li-Ion Batteries
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Solution Overview
Problem
Lithium ion batteries face challenges in cycling stability and rate capability, especially at elevated temperatures, and energy density, with nickel-rich cathode materials prone to rapid failure due to gas evolution and mechanical damage.
Innovation Solution
A process for producing mixed lithium-transition metal oxides with a concentration gradient in transition metal cations and constant lithium distribution, achieved by forming spherical particles of transition metal carbonates or hydroxides and subjecting them to thermal treatment between 800°C to 950°C, resulting in improved cathode materials for lithium ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-rich cathode materials are used to increase energy density, then specific capacity and energy density are improved, but cycling stability deteriorates and gas evolution occurs leading to rapid battery failure
Solution Approach 1:
The patent applies local quality by creating a non-uniform concentration distribution of transition metal cations within the cathode material particles. The concentration of at least one transition metal cation has a relative extreme value that is neither at the center nor at the edge, creating zones with different compositional properties. This allows the material to simultaneously achieve high nickel content for capacity while having regions with modified composition that suppress gas evolution and improve cycling stability.
2Ease of manufacture
If conventional uniform cathode materials are used to maintain manufacturing simplicity, then ease of manufacture is preserved, but rate capability deteriorates especially at elevated temperatures
Solution Approach 1:
The patent applies parameter changes by modifying the concentration parameters of transition metal cations within the particle structure. Instead of uniform composition, the concentration of at least one transition metal cation varies spatially with a relative extreme value inside the particle. This compositional parameter variation enhances rate capability and temperature performance while maintaining compatibility with conventional manufacturing processes for producing spherical particles and performing solid-state reactions.
3Device complexity
If uniform lithium distribution is maintained for material simplicity, then manufacturing ease is preserved, but cycling stability at elevated temperatures deteriorates
Solution Approach 1:
The patent applies local quality by creating spatially varying concentration of transition metal cations within the cathode particles. The concentration profile with extreme values inside the particle creates local compositional zones that optimize electrochemical performance. This non-uniform distribution improves cycling stability at elevated temperatures by controlling ion transport and reducing structural degradation, while lithium maintains essentially constant concentration for charge balance.
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 process enhances the cycling stability and rate capability of lithium ion batteries at high temperatures without compromising energy density, ensuring better performance and safety by optimizing the distribution of transition metals within the oxide particles.
Implementation Method 1
subjecting them to thermal treatment between 800°C to 950°C
Data Source
AI summary
A process is described for producing mixed oxide in particulate form, comprising cations of lithium and cations of at least two transition metals selected from the group consisting of nickel, cobalt, manganese, titanium, vanadium, chromium and iron, as are mixed oxides produced by this process.