dLMFP Cathode Blend for Li-Ion Batteries With Better Cycle Life
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Solution Overview
Problem
Existing positive electrode materials for lithium-ion secondary batteries face challenges such as low capacity per unit mass, poor cycling life, limited rate capacity, and difficulties in battery management system monitoring due to flat charge/discharge plateaus, along with safety concerns from insufficient heat stability and toxicity issues.
Innovation Solution
A blend of doped lithium manganese iron phosphate (dLMFP) with lithium nickel cobalt manganese oxide (NMC) and/or lithium nickel cobalt aluminum oxide (NCA) compounds is used, with dLMFP being the predominant component, enhancing electrochemical performance and providing a voltage slope for better battery management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If LiCoO2 is used as the positive electrode active material, then high reversible capacity and long lifetime are achieved, but toxicity and high cost occur
Solution Approach 1:
The patent modifies the chemical composition parameters of the positive electrode material by using LiFePO4 instead of LiCoO2, changing the metal element from cobalt to iron, which eliminates toxicity while maintaining structural stability and long cycle life
Solution Approach 2:
The patent replaces expensive cobalt-based materials with cheaper iron-based materials (LiFePO4), significantly reducing material cost while achieving comparable or superior lifetime performance through improved structural stability
2Temperature
If LiFePO4 is used as the positive electrode active material, then low cost and good thermal stability are achieved, but low electron conductivity occurs
Solution Approach 1:
The patent creates a composite structure by coating LiFePO4 particles with conductive materials such as carbon or metal oxides, combining the thermal stability of LiFePO4 with the high electron conductivity of the coating layer, thereby resolving the conductivity limitation
Solution Approach 2:
The patent employs porous conductive coating structures that provide extensive surface area for electron transfer while maintaining good thermal stability, enhancing electron conductivity without compromising the inherent thermal safety of LiFePO4
3Use of energy by moving object
If LiMnPO4 is used as the positive electrode active material, then higher operating potential is achieved, but poor cycle life occurs
Solution Approach 1:
The patent optimizes the crystal structure parameters and chemical composition of LiMnPO4 through doping with other metal elements or controlling particle morphology, stabilizing the structure during cycling and preventing degradation while maintaining high operating potential
4Quantity of substance
If NCA compound is used as the positive electrode active material, then high capacity is achieved, but insufficient heat stability occurs
Solution Approach 1:
The patent introduces a thermal stable coating layer as an intermediary between the NCA active material and the electrolyte, which acts as a thermal barrier and protective interface, preventing direct exothermic reactions while allowing electrochemical functionality to proceed
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 blend improves energy density, cycle life, and rate capability while offering improved safety and stability, facilitating precise battery monitoring and management.
Implementation Method 1
an active material is a material which participates in the electrochemical reactions to produce electrical energy when the secondary cell is discharging
Implementation Method 2
lithiated oxides of transition metals of general formula LiMO2
Implementation Method 3
a blend of a doped lithium iron phosphate (dLMFP) with lithium nickel cobalt manganese oxide (NMC) and/or lithium nickel cobalt aluminum oxide (NCA) compounds
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3~4
AI summary
Provided is a positive electrode active material for a lithium-ion battery, the positive electrode active material including a blend of a doped lithium manganese iron phosphate (dLMFP) according to the formula: LiMnxFeyM1-x-yPO4, wherein 0.9<x+y<1; and M is one or more selected from the group consisting of Mg, Ca and Ba with one or both of a lithium nickel cobalt manganese oxide (NMC) compound having a Ni content greater than 0.6 relative to a total amount of metals other than Li and a lithium nickel cobalt aluminum oxide (NCA) compound. In particular, provided is a blend at a weight ratio of dLMFP to NMC and/or NCA (i.e., dLMFP : (NMC+NCA)) of >70:<30, such as 75:25, 80:20, 85:15, 90:10, etc.