Lithium Metal Oxide Cathode for High-Capacity Batteries
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Solution Overview
Problem
Conventional lithium secondary battery cathode materials face limitations in achieving high reversible capacity without requiring overcharge, which complicates manufacturing and poses safety risks due to oxygen evolution and reduced long-term stability.
Innovation Solution
A lithium metal oxide with a composition of Li x M y O 2, where 0.6 ≤ y ≤ 0.85 and 0 ≤ x + y ≤ 2, incorporating metallic elements like Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, and Sb, that exhibits cation mixing and does not require overcharge during the first cycles, characterized by specific XRD peaks and intensity ratios, and can be synthesized with a substoichiometric amount of lithium and coated with materials like carbon for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional lithium excess metal oxide materials are used to achieve high reversible capacity, then capacity can be increased, but overcharge during first cycles is required which leads to oxygen evolution, safety risks, and manufacturing complexity
Solution Approach 1:
The patent changes the stoichiometric parameters of the lithium metal oxide by controlling the ratio of lithium to transition metal atoms within specific ranges (0.6 ≤ y ≤ 0.85 and 0 ≤ x + y ≤ 2), which fundamentally alters the material's electrochemical behavior to eliminate oxygen evolution during first charge while maintaining high reversible capacity exceeding 150 mAh/g
Solution Approach 2:
The patent employs composite materials by combining lithium metal oxide with carbon coatings and various transition metal elements (Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Sn, Sb), creating a multi-component system that achieves high capacity without requiring overcharge, thereby improving both safety and performance
2Quantity of substance
If overcharge above 4.7 V is applied to achieve higher capacity, then capacity can be increased, but manufacturing complexity and cost increase
Solution Approach 1:
The patent modifies the compositional parameters of the cathode material to Li x M y O 2 with specific stoichiometric ratios, which intrinsically enables high capacity (＞150 mAh/g) at standard charging voltages below 4.7 V, eliminating the need for complex overcharge manufacturing processes
3Quantity of substance
If overcharge is used to achieve higher capacity, then capacity can be increased, but long-term stability and charge/discharge rate capability are reduced
Solution Approach 1:
The patent optimizes the stoichiometric parameters (x and y values) of the lithium metal oxide to achieve a balanced composition that provides high reversible capacity while maintaining structural stability during cycling, resulting in improved long-term stability and charge/discharge rate capability without requiring overcharge
Solution Approach 2:
The patent creates composite structures with carbon coatings and controlled transition metal compositions that enhance both capacity and stability, allowing the material to maintain high performance over extended cycling without the degradation associated with overcharge processes
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 material achieves a reversible capacity exceeding 150 mAh/g without overcharging, demonstrating enhanced stability and charge/discharge rate capability, and can be synthesized using methods involving elevated temperatures and precursor milling, resulting in a high-capacity lithium-ion battery with improved safety and manufacturing simplicity.
Implementation Method 1
subjecting said oxide to at least one lithium ion extraction-insertion cycle results in a reduction of the ratio of I'/I"
Implementation Method 2
The material is capable of cation mixing... capable of exhibiting a reversible capacity of more than 150 mAh/g
Implementation Method 3
when characterized by XRD, showing a. a peak whose intensity I' is the largest in the range 16-22 degrees 2θ... and b. a peak whose intensity I" is the largest in the range 42-46 degrees 2θ
Data Source
Figure 1
Figure 2(A)~2(C)
Figure 3~4
AI summary
This disclosure provides a positive electrode active lithium-excess metal oxide with composition LixMyO2 (0.6≤ y ≤ 0.85 and 0 ≤ x + y ≤ 2) for a lithium secondary battery with a high reversible capacity that is insensitive with respect to cation-disorder. The material exhibits a high capacity without the requirement of overcharge during the first cycles.