Mixed Metal Olivine Cathode for High Energy Density and Capacity
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Solution Overview
Problem
Current lithium-ion battery materials struggle to simultaneously achieve high energy density and specific capacity, with traditional design choices often prioritizing one over the other, and existing attempts have shown limited success in enhancing both properties.
Innovation Solution
A positive electrode material based on lithium-iron-manganese phosphate (LFMP) with specific dopant elements like cobalt, nickel, vanadium, and fluorine, optimized to achieve both high energy density and specific capacity through careful composition and doping, resulting in a material with an olivine structure that exhibits improved performance at high discharge rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional lithium-ion battery cathode materials are used, then either high energy density or high specific capacity can be achieved, but not both simultaneously
Solution Approach 1:
The patent applies composite materials by creating a mixed metal olivine structure combining lithium iron phosphate (LFP) and lithium manganese phosphate (LMP) in a nanocomposite configuration. This composite structure enables the material to achieve both high energy density (340 mWh/g at 20C discharge rate) and high specific capacity (110 mAh/g at 20C discharge rate) simultaneously, resolving the traditional trade-off between these two parameters.
Solution Approach 2:
The patent employs parameter changes by optimizing the molar ratios of metal phosphates (LiFe1-x-yMnxM'yPO4 where M = Co, Ni, or Cu) and controlling particle size at the nanoscale (10-100 nm). These parameter optimizations enable the material to achieve superior electrochemical performance with both high energy density and high specific capacity at fast discharge rates (20C rate).
2Quantity of substance
If cathode materials are optimized for high specific capacity, then energy storage capability increases, but power density and fast discharge capability decrease
Solution Approach 1:
The patent applies segmentation by dividing the cathode material into nanoscale particles (10-100 nm) of mixed metal olivine structure. This nanosegmentation significantly increases the surface area to volume ratio and reduces ion diffusion paths, enabling the material to achieve high power density (6800 mW/g at 20C discharge rate) while maintaining high specific capacity (110 mAh/g at 20C discharge rate).
Solution Approach 2:
The patent utilizes porous materials by creating a nanocomposite structure with high surface area and controlled porosity. The nanoscale mixed metal olivine particles provide extensive surface area for electrochemical reactions, enabling fast ion transport and electron transfer, which results in high power density while maintaining high capacity.
3Use of energy by moving object
If cathode materials are optimized for high energy density, then total energy storage increases, but specific capacity and charge/discharge rates decrease
Solution Approach 1:
The patent applies composite materials by synthesizing a nanocomposite of lithium iron phosphate and lithium manganese phosphate in a mixed metal olivine structure. This composite enables the material to achieve high energy density (340 mWh/g at 20C discharge rate) and high specific capacity (110 mAh/g at 20C discharge rate) simultaneously, breaking the traditional trade-off between energy density and specific capacity.
4Power
If fast charge and discharge rates are prioritized, then power capability improves, but energy density and total energy storage decrease
Solution Approach 1:
The patent employs parameter changes by optimizing the composition ratios of metal phosphates and controlling particle size at the nanoscale. These parameter optimizations enable the material to achieve both high power density (6800 mW/g at 20C discharge rate) and high energy density (340 mWh/g at 20C discharge rate), resolving the trade-off between power capability and energy density.
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 LFMP material with dopants achieves energy density of at least 340 mWh/g and specific capacity of at least 110 mAh/g at a 20C discharge rate, along with high power density, making it suitable for applications requiring fast charge and discharge capabilities.
Implementation Method 1
Batteries produce energy from electrochemical reactions
Implementation Method 2
lithium ions travel from the positive electrode to the negative electrode
Data Source
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AI summary
Improved positive electrode material and methods for making the same are described. Lithium-iron-manganese phosphate materials, doped with one or more dopant Co, Ni, V, and Nb, and methods for making the same are described. The improved positive electrode material of the present invention is capable of exhibiting improved energy density and/or specific capacity for use in wide range of applications. In certain embodiments, energy density of greater than 340 mWh/g is possible.