Lithium-Rich Cathode Material with Non-Rocksalt Layered Structure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithium-rich composite oxides based on the rocksalt-type structure suffer from unstable anion reactions and limited electrochemical reversibility, leading to structural instability and reduced energy capacity in lithium secondary batteries.
Innovation Solution
A positive electrode active material with a non-rocksalt-type structure is developed, featuring excess lithium present in both tetrahedral and octahedral sites to achieve charge balance while allowing for inappropriate site balance, forming a new stable un-hybridized oxygen state and suppressing irreversible structural changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-rich composite oxide with rocksalt-type structure is used to achieve high capacity energy, then energy capacity is improved, but structural stability deteriorates leading to phase collapse and limited electrochemical reversibility
Solution Approach 1:
The patent changes the fundamental structural parameter from rocksalt-type to non-rocksalt-type layered structure, while maintaining lithium-rich composition (Li1+xM1−xO2 where x>0). This parameter change in crystal structure prevents the phase collapse that occurs in rocksalt-type materials when lithium is deintercalated, thereby maintaining structural stability while achieving high energy capacity through both transition metal and oxygen redox reactions.
Solution Approach 2:
The patent uses composite oxide materials with multiple transition metals (e.g., Li1.2Ni0.13Mn0.54Co0.13O2) combining different metal elements to achieve synergistic effects. The composite structure provides both high capacity through multi-metal redox and enhanced structural stability, while the non-rocksalt layered configuration prevents phase transformation and maintains electrochemical reversibility.
2Quantity of substance
If excess lithium is added to achieve charge balance and high capacity, then energy capacity is improved, but site balance becomes inappropriate leading to unstable anion reactions
Solution Approach 1:
The patent changes the structural parameter from rocksalt-type to non-rocksalt layered structure, which fundamentally alters the oxygen environment. In the non-rocksalt layered structure, oxygen ions are stabilized in a different coordination environment that prevents unstable anion reactions even when excess lithium (x>0) is present for charge balance, thereby maintaining both high capacity and anion reaction stability.
Solution Approach 2:
The patent creates a specific local structure around oxygen ions in the non-rocksalt layered configuration, where oxygen is coordinated in a stable environment distinct from the rocksalt structure. This local structural quality around oxygen prevents anion reaction instability while allowing excess lithium to be incorporated for charge balance and high capacity energy storage.
3Quantity of substance
If lithium is deintercalated to increase energy capacity, then capacity is improved, but irreversible structural change occurs reducing electrochemical reversibility
Solution Approach 1:
The patent changes the crystal structure parameter from rocksalt-type to non-rocksalt layered structure, which fundamentally prevents the phase collapse that occurs during lithium deintercalation. The non-rocksalt layered structure maintains structural integrity even when lithium is removed, enabling reversible lithium insertion/extraction and maintaining high electrochemical reversibility while achieving increased energy capacity.
Solution Approach 2:
The non-rocksalt layered structure acts as a pre-established stable framework that cushions against structural collapse during lithium deintercalation. This prior structural configuration prevents irreversible phase changes before they can occur, allowing repeated lithium insertion and extraction cycles while maintaining capacity and structural stability.
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 non-rocksalt-type structure enhances electrochemical performance and energy capacity by stabilizing anion reactions, reducing voltage and capacity loss, and improving cycle stability compared to traditional rocksalt-type structures.
Implementation Method 1
forming a new stable un-hybridized oxygen state and suppressing irreversible structural changes
Implementation Method 2
Materials having such a structure mainly undergo a transition metal-based oxidation/reduction reaction, in which electrons are supplied by a 3d transition metal when lithium is intercalated/deintercalated
Implementation Method 3
preparing a mixture by mixing a plurality of metal precursors; primarily sintering the mixture by heating at a first temperature range
Data Source
AI summary
A positive electrode active material for a lithium secondary battery and a method for manufacturing the same. The positive electrode material, wherein excess lithium is present to be inappropriate for a site balance, has a composition of Li1+x+yM1−yO2 where x is an amount in which the excess lithium enters an tetrahedral site between a lithium layer and a transition metal layer, y is an amount in which the excess lithium enters an octahedral site of the transition metal layer, x and y are values that satisfy the charge balance, 0<x, y<1, and M is at least one selected from Al, Mg, Mn, Ni, Co, Cr, V, Fe, Nb, Mo, Ru, Zr, and Ir, and 3d, 4d, and 5d transition metals except for the listed metals, and a layered non-rocksalt-type structure.