TiO2-Coated Positive Electrode Material for Low-Resistance Battery Cycling
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Solution Overview
Problem
Conventional positive electrode active materials coated with TiO2 in non-aqueous electrolyte secondary batteries suffer from high reaction resistance and poor output characteristics, with an increase in resistance after repeated charge-discharge cycles.
Innovation Solution
A positive electrode active material is developed with a core portion containing a lithium transition metal composite oxide, coated with a layer of brookite-type TiO2 and rutile-type TiO2 to enhance ion insertion and release, mechanical strength, and reduce reaction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a coating is provided on the positive electrode active material to improve battery characteristics, then output characteristics are improved, but reaction resistance increases
Solution Approach 1:
The patent applies composite materials by combining two different TiO2 polymorphs (brookite and rutile) in the coating layer. The brookite-type TiO2 provides high ion insertion/release performance to reduce reaction resistance, while the rutile-type TiO2 provides mechanical strength to maintain coating integrity during cycling, thus resolving the contradiction between improving output characteristics and reducing reaction resistance
Solution Approach 2:
The patent applies local quality by creating a coating layer with spatially distributed functional properties. The coating contains both brookite-type TiO2 (for ion transport functionality) and rutile-type TiO2 (for mechanical strength), where each polymorph is distributed throughout the coating layer to provide localized functions that collectively resolve the contradiction between reaction resistance and output characteristics
2Power
If a coating is provided on the positive electrode active material, then output characteristics are improved, but resistance increases after repeated charge-discharge cycles
Solution Approach 1:
The patent uses composite materials combining brookite-type TiO2 and rutile-type TiO2 in the coating layer. The rutile-type TiO2 provides high mechanical strength that prevents coating fracture and peeling during charge-discharge cycling, while the brookite-type TiO2 maintains ion transport efficiency, thus resolving the contradiction between improving output characteristics and maintaining low resistance after cycling
Solution Approach 2:
The patent applies beforehand cushioning by providing a pre-formed coating layer on the positive electrode active material before battery assembly. This coating layer, containing both brookite and rutile TiO2, is designed in advance to prevent mechanical fracture and peeling during subsequent charge-discharge cycles, thus cushioning against the degradation that would otherwise occur and resolve the contradiction between output characteristics and cycle 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 proposed active material improves output and cycle characteristics by reducing reaction resistance and preventing material fracture during charge-discharge cycles, leading to better performance in non-aqueous electrolyte secondary batteries.
Implementation Method 1
brookite-type TiO2 considered to have the effect of facilitating insertion and release of an Li ion
Implementation Method 2
rutile-type TiO2 considered to have high mechanical strength, it is possible to suitably prevent a fracture in the positive electrode active material and peeling of the coat portion during a charge-discharge cycle
Data Source
AI summary
There is provided a positive electrode active material capable of giving excellent output characteristics to a non-aqueous electrolyte secondary battery and suppressing an increase in resistance after cyclic charge and discharge. The positive electrode active material disclosed herein includes a core portion which contains a lithium transition metal composite oxide, and a coat portion with which at least part of a surface of the core portion is coated. The coat portion contains brookite-type TiO2 and rutile-type TiO2.