Carbonate Precursor Design for High-Manganese Cathode Materials
Solution Overview
Problem
Lithium nickel manganese cobalt oxide cathode materials with high lithium and manganese content face challenges in achieving high tap density and discharge capacity due to poor electronic conductivity and slow lithium diffusion, along with issues related to impurities and overcharge stability in current manufacturing processes.
Innovation Solution
A carbonate precursor compound with specific particle size, tap density, and dopant composition is used to produce lithium manganese based oxide powders, which are then sintered to form cathode materials with improved electrochemical performance, including high discharge capacity and acceptable tap density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HLM cathode materials are prepared as nano-structured or porous powders to improve electronic conductivity and lithium diffusion, then electrochemical performance is improved, but tap density decreases
Solution Approach 1:
The patent changes the particle size parameter to a specific range (4.25-20 μm D50) and controls the tap density parameter (1.0-2.0 g/cm³) to achieve optimal balance between electrochemical performance and volumetric energy density, resolving the contradiction between nano-structure benefits and density requirements
Solution Approach 2:
The patent uses composite carbonate precursors containing multiple metal carbonates (Ni, Mn, Co, and optionally Al, Mg, Ti, Zr) with specific compositional ratios to create HLM materials that maintain both good electrochemical performance and acceptable tap density through synergistic effects of different metal elements
2Quantity of substance
If high lithium and manganese content is used in HLM cathode materials to achieve high specific capacity, then discharge capacity is improved, but electronic conductivity and lithium diffusion slow down
Solution Approach 1:
The patent optimizes the compositional parameters within the HLM phase diagram, specifically controlling the Li:M ratio and the proportions of Ni, Mn, Co, and dopant elements to achieve a balance where high capacity is maintained while conductivity and diffusion rates are improved through appropriate compositional tuning
Solution Approach 2:
The patent introduces dopant elements (Al, Mg, Ti, Zr) at specific locations in the crystal structure to locally improve electronic conductivity and lithium diffusion pathways without compromising the overall high lithium and manganese content that provides high capacity
3Manufacturing precision
If mixed transition metal hydroxides are used as precursors to achieve well-mixed transition metal cations, then cathode material performance is improved, but sulfur impurities increase and removal becomes difficult and expensive
Solution Approach 1:
The patent extracts the harmful sulfur element from the precursor system by replacing sulfate-based mixed hydroxide precursors with carbonate-based precursors, thereby eliminating sulfur impurity generation while maintaining the benefit of well-mixed metal cations through carbonate coprecipitation
Solution Approach 2:
The patent employs carbonate precursors that can be easily decomposed during sintering to leave pure oxide products without sulfur contamination, replacing the problematic sulfate-based precursors that require complex and expensive sulfur removal 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 resulting lithium nickel manganese cobalt oxide cathode materials exhibit superior discharge capacity and cycle stability, suitable for high-energy density applications in lithium-ion batteries.
Implementation Method 1
The carbonate precursor is sintered with a lithium precursor for forming the cathode material
Implementation Method 2
The oxide can be conceived as a solid state solution of Li2MnO3 and LiMO2
Implementation Method 3
Mixed carbonates (for example, the precipitation of a flow of Na2CO3 with a flow of M-SO4)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A carbonate precursor compound of a lithium manganese based oxide powder for a positive electrode of a rechargeable battery, the oxide having the general formula Li1+vM1-vO2, wherein -0.03≤v≤0.25, wherein M is a composition comprising at least 50mol% of manganese, and wherein the carbonate precursor compound has a secondary particle size D50 expressed in µm, and a tap density TD expressed in g/cm3, with either ≤ TD ≤ (2.78*D50)/(D50+7.23) and the compound having a particle size distribution having a span S≤1.8 with S=(D90-D10)/D50; or 1 ≤ TD ≤ (2.78*D50)/(D50+7.50).