Lithium Manganese Phosphate Cathode Doping for Rate and Cycle Stability
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Solution Overview
Problem
Lithium manganese phosphate positive electrode active materials in secondary batteries face challenges with poor rate performance, cycling performance, and high-temperature stability, which existing solutions attempt to address through coating or doping but require further improvement.
Innovation Solution
Simultaneous doping of lithium manganese phosphate at Li, Mn, P, and O sites with specific elements to optimize the chemical formula LiaAxMn1-yByP1-zCzO4-nDn, where A, B, C, and D are selected from specific elements, improving the material's rate performance, cycle performance, and high-temperature stability by reducing lattice change rate, surface activity, and antisite defect concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium manganese phosphate is used as positive electrode active material, then the battery can achieve good theoretical energy density, but the rate performance is poor
Solution Approach 1:
The patent applies parameter changes by doping lithium manganese phosphate at multiple sites (Li, Mn, P, O) with specific elements (A, B, C, D) to optimize the chemical formula LiaAxMn1-yByP1-zCzO4-nDn. This multi-site doping strategy modifies the crystal structure parameters and electronic properties, enabling the material to achieve both high energy density and improved rate performance by facilitating faster lithium ion diffusion and electron transport.
Solution Approach 2:
The patent creates a composite doped structure where multiple elements (A, B, C, D) are incorporated into the lithium manganese phosphate lattice at different sites. This composite approach combines the advantages of different dopants to synergistically improve both energy density and rate performance, transforming the single-phase material into a multi-element composite with enhanced electrochemical properties.
2Use of energy by moving object
If lithium manganese phosphate is used as positive electrode active material, then the battery can achieve good theoretical energy density, but the cycling performance is poor
Solution Approach 1:
The patent uses parameter changes through controlled doping at multiple crystallographic sites to stabilize the crystal structure of lithium manganese phosphate. The doping elements (A, B, C, D) at specific concentrations (x, y, z, n) reduce lattice distortion and suppress phase transitions during cycling, thereby maintaining structural integrity and improving cycling performance while preserving high energy density.
Solution Approach 2:
The patent applies beforehand cushioning by pre-doping the lithium manganese phosphate structure with stabilizing elements before electrochemical cycling begins. This preventive doping strategy cushions against structural degradation, Jahn-Teller distortion, and manganese dissolution that would otherwise occur during repeated charge-discharge cycles, ensuring long-term cycling stability.
3Use of energy by moving object
If lithium manganese phosphate is used as positive electrode active material, then the battery can achieve good theoretical energy density, but the high-temperature stability is poor
Solution Approach 1:
The patent applies parameter changes by incorporating thermally stabilizing dopants (A, B, C, D) at multiple sites in the lithium manganese phosphate structure. These dopants modify the thermal properties of the material, raising the decomposition temperature and suppressing exothermic reactions, thereby achieving both high energy density and improved high-temperature stability through compositional optimization.
Data Source
AI summary
A positive electrode plate includes a positive electrode current collector, a positive electrode film layer provided on at least one surface of the positive electrode current collector, and a conductive undercoat layer between the positive electrode current collector and the positive electrode film layer. The positive electrode film layer includes a positive electrode active material having a chemical formula of LiaAxMn1-yByP1-zCzO4-nDn, and the conductive primer layer includes a first polymer, a first water-based binder and a first conductive agent.