Nickel-Rich Cathode Coating to Remove Residual Lithium Safely
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Solution Overview
Problem
Lithium nickel-based composite oxides used in rechargeable lithium batteries form residual lithium, leading to carbon dioxide generation during charging and discharging, which deteriorates cell stability, and conventional washing methods to remove residual lithium cause structural damage and deterioration.
Innovation Solution
A method involving controlled washing and subsequent addition of a second lithium compound, along with a coating layer, to minimize structural damage and enhance the capacity and cycle-life of the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface of the positive electrode active material is washed to remove residual lithium, then cell stability is improved, but structural damage and structural deterioration occur
Solution Approach 1:
The patent changes the washing parameters by controlling the pH value of the washing solution within 2-7, temperature at 20-50°C, and washing time at 5-30 minutes. These parameter optimizations enable effective removal of residual lithium while minimizing structural damage to the positive electrode active material particles.
Solution Approach 2:
The patent introduces a coating layer as an intermediary substance on the surface of the positive electrode active material particles. This coating layer protects the internal structure from washing damage while allowing controlled removal of residual lithium, thus resolving the contradiction between cell stability improvement and structural integrity maintenance.
2Object-generated harmful factors
If washing is performed to remove residual lithium, then carbon dioxide generation during charging and discharging is reduced, but capacity and cycle-life are compromised due to structural deterioration
Solution Approach 1:
The patent optimizes washing parameters including pH (2-7), temperature (20-50°C), and time (5-30 minutes) to achieve the right balance between removing residual lithium (reducing CO2 generation) and preserving the structural integrity needed for long cycle-life and high capacity.
Solution Approach 2:
The coating layer serves as a protective intermediary that allows sufficient washing to reduce carbon dioxide generation while preventing excessive structural deterioration that would harm capacity and cycle-life.
3Reliability
If conventional washing methods are used to remove residual lithium, then cell stability is improved, but manufacturing precision is reduced due to structural damage
Solution Approach 1:
The patent precisely controls washing parameters (pH 2-7, temperature 20-50°C, time 5-30 minutes) to maintain particle structure integrity while effectively removing residual lithium, thereby achieving both cell stability and manufacturing precision.
Solution Approach 2:
The coating layer acts as a protective intermediary during the washing process, enabling precise control of the washing action to remove residual lithium without damaging the particle structure, thus maintaining manufacturing precision.
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 method improves battery capacity and cycle-life while reducing structural damage by effectively managing residual lithium and maintaining structural integrity.
Implementation Method 1
a coating layer located on a surface of the core particle and comprising one element or a combination thereof selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr
Implementation Method 2
subjecting the second mixture to a second heat treatment to obtain a positive electrode active material
Data Source
AI summary
Disclosed are a positive electrode active material for a rechargeable lithium battery and a method for preparing the same, a positive electrode active material including: a core particle comprising a lithium nickel-based composite oxide represented by Chemical Formula 11; and a coating layer located on a surface of the core particle and comprising one element or a combination thereof selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, wherein the positive electrode active material has a value defined by Mathematical Formula 1 of greater than or equal to about 5.wherein, in Chemical Formula 11, 0.9≤a11≤1.2, 0.3≤x11<1, 0<y11≤0.7, 0≤z11≤0.7, 0.9≤x11+y11+z11≤1.1, and 0≤b11≤0.11, M11 and M12 are each independently one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from F, P, and S,∑[Mx (EP-EDS)/Mx (ICP)]Mathematical Formula 1wherein Mx denotes a metal component contained in the coating layer, Mx (EP-EDS) denotes a mol % of the metal component Mx relative to total metals excluding lithium, present on the surface of the positive electrode active material as measured by Electron Probe-Energy Dispersive Spectroscopy (EP-EDS), and Mx (ICP) denotes a mol % of the metal component Mx relative to total metals excluding lithium, present in the entirety (surface and core) of the positive electrode active material as measured by Inductively Coupled Plasma analysis.