Composite Cathode Material for High Capacity Lithium Batteries
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Solution Overview
Problem
Current lithium secondary batteries face limitations in achieving high capacity and thermal stability, with existing materials either having unstable structures, poor charge/discharge cyclability, or compromising on capacity for improved thermal stability, leading to safety concerns such as battery swelling or explosion due to electrolyte reactions.
Innovation Solution
A lithium/nickel/cobalt/manganese complex metal oxide with a specific composition (LiaNi1−(v+w+x+y+z)MnvCowMxM′yM″zO2) is developed, where M, M′, and M″ are selected from Al, Mg, Sr, Ca, P, Pb, Y, and Zr, with controlled particle size and shape, and a co-precipitation process followed by heat treatment to enhance thermal stability and reduce reactivity with the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium/nickel complex oxide is used to achieve high capacity, then battery capacity is improved, but thermal stability deteriorates leading to safety issues
Solution Approach 1:
The patent uses a composite cathode material comprising Li2SiO3 and Li1-aNiaCobMn1-b-cO2, where the Li2SiO3 component provides thermal stability while the LiNi-a-bCobMn1-b-cO2 component provides high capacity. This composite structure allows the battery to achieve 170-175 mAh/g capacity while maintaining thermal stability through the protective Li2SiO3 layer that prevents electrolyte decomposition and oxygen release.
2Reliability
If lithium/manganese complex oxide is used to improve thermal stability, then thermal stability is improved, but battery capacity decreases
Solution Approach 1:
The patent merges the advantages of Li2SiO3 (excellent thermal stability) with LiNi-a-bCobMn1-b-cO2 (high capacity) into a single composite cathode material. The Li2SiO3 component contributes thermal stability while the LiNi-a-bCobMn1-b-cO2 component contributes high capacity, achieving both thermal stability and high battery capacity simultaneously through their synergistic combination.
3Quantity of substance
If lithium/nickel complex oxide is used to achieve high capacity, then battery capacity is improved, but charge/discharge cyclability deteriorates
Solution Approach 1:
The composite structure of Li2SiO3 and Li1-aNiaCobMn1-b-cO2 provides both high capacity and excellent charge/discharge cyclability. The Li2SiO3 component stabilizes the cathode structure during cycling, preventing structural degradation, while the LiNi-a-bCobMn1-b-cO2 component maintains high capacity, resulting in a material that achieves both high capacity and long cycle life.
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 cathode active material achieves high capacity (170-175 mAh/g) with improved thermal stability, reducing heat generation and enhancing safety by minimizing exothermic reactions, thus addressing the limitations of existing materials.
Implementation Method 1
co-precipitating a mixed metal solution composed of a nickel salt solution, a cobalt salt solution and a manganese salt solution in the presence of a complexing agent and a precipitating agent
Implementation Method 2
subjecting the mixture to heat treatment at a temperature of 300 to 900° C. for 5 to 30 hours in normal air or dry air or in an oxygen atmosphere
Data Source
AI summary
Provided are a cathode active material for a non-aqueous electrolyte lithium secondary battery, a process for preparing the same and a lithium secondary battery comprising the same. The cathode active material for a non-aqueous electrolyte lithium secondary battery is represented by the formula LiaNi1−(v+w+x+y+z)MnvCowMxM′yM″zO2 wherein M, M′ and M″ are independently selected from the group consisting of Al, Mg, Sr, Ca, P, Pb, Y and Zr, and mixtures thereof, a is in a range of 0.9 to 1.05, 1−(v+w+x+y+z) is in a range of 0.685 to 0.745, v is in a range of 0.05 to 0.06, w is in a range of 0.20 to 0.24, and x+y+z is in a range of 0.005 to 0.015.