O2-Phase Lithium Cobalt Cathode for High-Voltage Cycle Stability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium cobaltate-based positive electrode materials face challenges in maintaining high specific capacity, structural reversibility, and stability under high voltages, leading to irreversible phase transitions and capacity attenuation due to interface reactions and cobalt dissolution.

Innovation Solution

A lithium-cobalt composite oxide with an O2 phase, LixNazCo1-yMyO2, is developed, featuring pores and gaps to accommodate volume changes, supported by sodium occupancy, which enhances structural stability and reduces lithium ion migration energy, thereby improving cycle performance and stability at high voltages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If LiCoO2 is charged to higher voltage (>4.6V) to achieve higher specific capacity, then more Li+ can be deintercalated, but irreversible phase transitions occur (O3→H1-3→O1) reducing cycle performance and safety

Engineering Contradiction:

Improvespecific capacityVSAvoidcycle performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the crystal structure parameter from O3 phase to O2 phase, and introduces Na doping to modify the chemical composition. This parameter change allows the material to operate at high voltages (>4.6V) without undergoing irreversible phase transitions, achieving both high specific capacity (92.6 mAh/g at 4.8V) and good cycle performance (81.4% retention after 50 cycles)

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system by doping Na into the LiCoO2 lattice to form Li1-xNaxCoO2, and further introduces surface modification with Al2O3 coating. This composite approach combines the high voltage stability of O2 phase with the benefits of Na doping and protective coating, resolving the contradiction between high capacity and cycle stability

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If LiCoO2 is charged to higher voltage to achieve higher specific capacity, then more Li+ is deintercalated, but cobalt metal dissolves severely and interface reactions increase

Engineering Contradiction:

Improvespecific capacityVSAvoidcobalt dissolution

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent introduces Al2O3 coating as an intermediary layer between the LiCoO2 electrode and the electrolyte. This coating layer acts as a protective barrier that prevents direct contact between the high-voltage electrode and electrolyte, thereby suppressing cobalt dissolution and interface reactions while allowing lithium ion transport, achieving both high capacity and low harmful effects

Inventive Principle:

Principle #24Intermediary (Mediator)

3Power

If conventional electrolytic solution is used at high voltage, then the battery can operate at high voltage, but the electrolyte decomposes and fails quickly leading to drastic capacity attenuation

Engineering Contradiction:

ImprovevoltageVSAvoidelectrolyte stability

Core Design Contradiction:

PowerVSDuration of action of stationary object

Solution Approach 1:

The patent applies preliminary protective measures by introducing Na doping and Al2O3 coating before the electrolyte can decompose. The Na doping stabilizes the crystal structure at high voltage, and the Al2O3 coating creates a protective interface that prevents electrolyte decomposition, thereby enabling high-voltage operation with extended electrolyte stability and capacity retention

Inventive Principle:

Principle #9Preliminary anti-action

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 LixNazCo1-yMyO2 material exhibits excellent structural reversibility and cycle stability, suppressing crystal structure collapse and interface failure, with delithiation exceeding 95% at 4.7 V, and lower electrolyte requirements, ensuring prolonged battery performance.

Implementation Method 1

a lithium-cobalt composite oxide with an O2 phase, LixNazCo1-yMyO2, is developed, featuring pores and gaps to accommodate volume changes, supported by sodium occupancy, which enhances structural stability and reduces lithium ion migration energy

Methodology Applied

Scientific EffectCrystal structure stabilization:

Implementation Method 2

featuring pores and gaps to accommodate volume changes

Methodology Applied

Scientific EffectVolume change accommodation: Porosity

Implementation Method 3

a lithium-ion battery. As an important component of a lithium-ion battery, a positive electrode material exerts a significant impact on the performance of the battery

Methodology Applied

Scientific EffectElectrochemical intercalation:

Data Source

PatentUS12519105B2Positive electrode material and electrochemical device including same

Publication Date: 2026.01.06 NINGDE AMPEREX TECHNOLOGY LTD

AI summary

A positive electrode material contains LixNazCo1-yMyO2, where 0.6<x<0.85, 0≤y<0.15, 0≤z<0.03, and M is at least one selected from Al, Mg, Ti, Mn, Fe, Ni, Zn, Cu, Nb, Cr, or Zr. Under a high voltage (greater than 4.6 V). The positive electrode material exhibits a considerable discharge capacity and desirable structural reversibility and cycle stability.