Lithium Manganese Oxide Cathode with Reversible Phase Transition
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Solution Overview
Problem
Existing cathode active materials in lithium secondary batteries face challenges with irreversible structural changes during charging and discharging, limiting their ability to achieve high theoretical capacity and lifespan due to alkali ion desorption, which affects energy density and cycle stability.
Innovation Solution
A method involving the synthesis of sodium manganese oxide followed by ion-exchange with a lithium precursor to form lithium manganese oxide, utilizing hydrothermal or microwave processes and incorporating crystal water to induce reversible phase transitions, maintaining a two-dimensional layered crystal structure and allowing lithium insertion and desorption without structural collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional cathode active materials are used, then high energy density can be achieved, but irreversible structural changes occur during charging/discharging leading to limited lifespan
Solution Approach 1:
The patent changes the chemical composition parameters of the cathode active material by incorporating specific metal elements (Ni, Co, Mn, Zn) in controlled ratios and introducing crystal water content (0.1-0.5 molecules per formula unit). This compositional parameter change enables reversible phase transitions during charging/discharging, resolving the contradiction between energy density and lifespan by allowing structural flexibility without collapse.
Solution Approach 2:
The patent creates a composite cathode active material with multiple metal elements (Ni, Co, Mn, Zn) and crystal water in a specific composite structure. This multi-component composite enables both high capacity (energy density) and structural stability (lifespan) through synergistic effects of different elements and reversible phase transitions.
2Quantity of substance
If alkali ion desorption is increased to improve capacity, then energy density increases, but structural stability deteriorates leading to irreversible changes
Solution Approach 1:
The patent introduces dynamic reversibility to the cathode structure by enabling phase transitions that can switch between different structural states during charging/discharging. The crystal water and metal element composition allow the structure to dynamically adapt to ion insertion/extraction without permanent damage, maintaining stability while achieving high capacity.
Solution Approach 2:
The patent incorporates crystal water and specific metal element combinations as a protective mechanism before structural collapse can occur. This pre-built structural buffer absorbs the stress of repeated ion desorption/insertion cycles, preventing irreversible structural changes while allowing high capacity operation.
3Use of energy by moving object
If high voltage charging is applied to increase energy density, then capacity improves, but structural degradation accelerates
Solution Approach 1:
The patent modifies the structural parameters of the cathode material through controlled crystal water content and metal element ratios, creating a more resilient structure that can withstand high voltage charging. The compositional parameters are optimized to balance energy density achievement with structural integrity maintenance under high voltage conditions.
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
This approach enables a cathode active material with reversible phase transitions, maintaining high capacity and lifespan characteristics even after repeated charging and discharging, achieving capacity retention rates above 80% after 20 cycles and exhibiting excellent energy density and stability.
Implementation Method 1
the step (A) may include synthesizing the sodium manganese oxide by a hydrothermal synthesis in distilled water or a microwave process of the manganese precursor
Implementation Method 2
the step (A) may include synthesizing the sodium manganese oxide by a hydrothermal synthesis in distilled water or a microwave process of the manganese precursor
Implementation Method 3
The step (B) may include preparing the lithium manganese oxide by performing ion-exchange between sodium and lithium of the sodium manganese oxide in an aqueous lithium precursor solution
Implementation Method 4
A cathode active material containing the lithium manganese oxide may exhibit a reversible phase transition during charging/discharging
Data Source
AI summary
The inventive concept discloses a method for preparing a cathode active material containing a lithium manganese oxide exhibiting a reversible phase transition, and exhibiting electrochemical characteristics of the lithium manganese oxide through the reversible phase transition including (A) synthesizing a sodium manganese oxide using a manganese precursor, and (B) reacting the sodium manganese oxide with a lithium precursor to synthesize the lithium manganese oxide, or including (C) directly synthesizing the lithium manganese oxide.