Lithium Manganese Phosphate Electrode with Carbon Coating
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Solution Overview
Problem
Nonaqueous electrolyte batteries using olivine type lithium manganese phosphate materials face challenges in achieving good charge/discharge properties due to low electron and lithium ion conductivity, which hinders efficient energy storage and safety in large-scale applications.
Innovation Solution
A positive electrode active material with a specific composition of LiMn1-xMxPO4 (where M represents elements like Mg, Fe, Ni, Co, Ti, and Zr) is developed, with controlled average pore diameter and total pore volume, along with surface and internal carbon coating to enhance conductivity and reaction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If olivine type lithium manganese phosphate materials are used as positive electrode active materials, then cost and safety are improved, but electron conductivity and lithium ion conductivity deteriorate, resulting in poor charge/discharge properties
Solution Approach 1:
The patent uses composite materials by combining olivine type lithium manganese phosphate with carbon coating and metal element doping. The carbon coating layer provides electrical conductivity while the metal elements (Mg, Fe, Ni, Co, Ti, Zr) doping into the crystal structure enhances both electron conductivity and lithium ion conductivity, resolving the contradiction between safety and charge/discharge properties
Solution Approach 2:
The patent applies local quality by creating a core-shell structure where the interior maintains the olivine type lithium manganese phosphate composition for safety and stability, while the surface is modified with carbon coating and metal element incorporation to enhance conductivity. This localized modification allows different regions to have different properties optimized for their specific functions
2Power
If carbon coating is applied to enhance electron conductivity, then charge/discharge properties are improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated approach by combining carbon coating with metal element doping in a unified synthesis process. Rather than applying carbon coating as a separate post-treatment step, the metal elements are incorporated during the hydrothermal synthesis of the olivine type lithium manganese phosphate, and carbon coating is applied simultaneously or in an integrated manner, simplifying the overall manufacturing process while achieving both conductivity enhancement and structural stabilization
3Power
If particle size is reduced and lithium diffusion distance is shortened, then reaction area increases and charge/discharge properties improve, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by optimizing the hydrothermal synthesis conditions (temperature, pressure, time, pH, precursor ratios) to directly control particle size and morphology during the synthesis process. By adjusting these parameters, the patent achieves uniform fine particles with controlled size distribution and optimized lithium diffusion paths, eliminating the need for post-synthesis size reduction processes and their associated precision challenges
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 solution results in improved charge/discharge performance and rate properties, ensuring both high energy density and safety for nonaqueous electrolyte batteries, suitable for large-scale applications.
Implementation Method 1
carbon coating for enhancing the electron conductivity
Implementation Method 2
charge/discharge is performed when lithium ions are transferred between a negative electrode and a positive electrode
Implementation Method 3
internal pores are filled with a carbonaceous material
Data Source
AI summary
A positive electrode active material includes LiMn1-xMxPO4 (wherein M represents at least one element selected from Mg, Fe, Ni, Co, Ti, and Zr; and 0≤x<0.5) and has an average pore diameter of 8 nm or more and not more than 25 nm and a total pore volume of 0.05 cm3/g or more and not more than 0.3 cm3/g.