Li3PO4-Coated Ni-Rich Cathode for High-Voltage Cycle Stability
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Solution Overview
Problem
High-voltage lithium-ion batteries face capacity fading and safety issues due to surface structural degradation of Ni-rich LiNixCoyMnzO2 cathode materials at elevated voltages, leading to unwanted side reactions and reduced cycling stability.
Innovation Solution
A modified cathode composition comprising a Ni-rich LiNixCoyMnzO2 portion coated with Li3PO4 and doped with elemental metals like Zr, Sn, Nb, Ta, Al, or Fe, combined with specific solid-state or liquid electrolytes, enhances structural stability and cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Ni-rich LiNixCoyMnzO2 cathode material is used to achieve high capacity, then battery capacity is improved, but surface structural degradation occurs at elevated voltages leading to capacity fading and safety issues
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where Ni-rich LiNixCoyMnzO2 core particles are coated with a protective layer of Li3PO4. This composite structure allows the high-capacity Ni-rich cathode material to maintain its capacity while the Li3PO4 coating layer protects against surface structural degradation and unwanted side reactions at elevated voltages, thereby improving cycling stability and safety.
2Quantity of substance
If Ni-rich LiNixCoyMnzO2 cathode material is used to achieve high capacity, then battery capacity is improved, but unwanted side reactions occur at elevated voltages
Solution Approach 1:
The patent uses Li3PO4 coating layer as an intermediary between the Ni-rich LiNixCoyMnzO2 cathode material and the electrolyte. This intermediate layer prevents direct contact and unwanted side reactions between the high-voltage cathode material and the electrolyte, while still allowing lithium ion transport. The coating acts as a protective mediator that eliminates harmful side reactions without significantly reducing battery capacity.
3Reliability
If surface coating is applied to prevent degradation, then cycling stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the coating process with the cathode material synthesis by performing both steps in a single calcination process. The Li3PO4 coating is applied by mixing lithium phosphate precursor with the Ni-rich NCM precursor, followed by one-step calcination that simultaneously forms the core-shell structure and completes the cathode material synthesis. This merged approach improves cycling stability while minimizing manufacturing complexity by eliminating separate coating steps.
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 modified cathode exhibits improved cycling stability and capacity retention, with capacity retention of 84.4% after 300 cycles at 0.2 C in liquid electrolyte batteries and 88.3% after 100 cycles in quasi-solid-state batteries, while maintaining a low cost and environmentally friendly production process.
Implementation Method 1
a second portion including Li3PO4, wherein: the second portion is coated on the first portion
Implementation Method 2
the first portion is doped with an elemental metal selected from at least one of Zr, Sn, Nb, Ta, Al, and Fe
Implementation Method 3
calcining the second mixture at a predetermined temperature for a predetermined time to form the composition
Data Source
AI summary
A composition includes a first portion including Ni-rich LiNixCoyMnzO2, where 0.5<x<1, 0<y<1, 0<z<1; a second portion including Li3PO4 such that the second portion is coated on the first portion, and the first portion is doped with an elemental metal selected from at least one of Zr, Sn, Nb, Ta, Al, and Fe. The molar ratio between Li3PO4 and Ni-rich LiNixCoyMnzO2 ranges from 0.76:100 to 3.8:100. A method of forming a composition includes mixing a metal precursor with nickel-cobalt-manganese (NCM) precursor to form a first mixture; adding a lithium-based compound to the first mixture to form a second mixture; and calcining the second mixture at a predetermined temperature for a predetermined time to form the composition.