Lithium-Titanium Coating for Battery Electrolyte Stability
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Solution Overview
Problem
Non-aqueous electrolyte batteries using lithium-titanium composite oxides face challenges in forming a stable coating film, leading to decomposition of the electrolyte and gas generation, especially when combined with manganese-containing positive electrodes, which affects battery performance and safety.
Innovation Solution
A lithium-titanium composite oxide particle with a coating layer containing phosphorous or sulfur compounds is used, which suppresses the decomposition of the non-aqueous electrolyte and alleviates the negative effects of manganese ions, maintaining high energy density and large-current characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If lithium-titanium composite oxide is used as the negative electrode active material, then rapid charging performance and low-temperature performance are improved, but the non-aqueous electrolyte decomposes continuously due to inability to form stable coating film
Solution Approach 1:
A coating layer containing phosphorous compound or sulfur compound is introduced as an intermediary between the lithium-titanium composite oxide and the non-aqueous electrolyte. This coating layer forms a stable interface that prevents direct contact between the electrolyte and the high-potential oxide surface, thereby suppressing continuous decomposition while maintaining rapid charging capability.
Solution Approach 2:
The negative electrode active material is transformed from a single material (lithium-titanium composite oxide) to a composite structure consisting of the oxide core surrounded by a protective coating layer containing phosphorous or sulfur compounds. This composite structure combines the high-performance characteristics of the oxide with the protective properties of the coating layer.
2Quantity of substance
If manganese-containing positive electrode is combined with lithium-titanium composite oxide negative electrode, then battery capacity is improved, but Mn ions elute and significantly decompose the non-aqueous electrolyte solution
Solution Approach 1:
The coating layer containing phosphorous or sulfur compounds acts as a mediator that blocks the migration path of Mn ions from the positive electrode to the negative electrode. This intermediary layer prevents Mn ions from reaching the lithium-titanium composite oxide surface where they would catalyze electrolyte decomposition, while allowing the high-capacity combination to function.
3Reliability
If carbonaceous material is used as negative electrode active material, then stable SEI coating film is formed limiting electrolyte decomposition, but lithium absorption/releasing potential is as low as about 0.1 V vs. Li/Li+
Solution Approach 1:
Instead of using a material with uniformly low potential (carbonaceous material at 0.1 V), the invention applies a protective coating layer with specific local properties (phosphorous or sulfur compounds) onto a high-potential material (lithium-titanium composite oxide at 1-2 V). This creates a localized protective environment at the interface while maintaining the overall high potential of the active material.
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 coating layer effectively limits electrolyte decomposition and gas generation, enhancing the stability and performance of lithium-titanium composite oxide-based batteries, particularly when used as both positive and negative electrodes, while maintaining high energy density and large-current capabilities.
Implementation Method 1
the coating layer being contained at least one element selected from the group consisting of phosphorous and sulfur or a phosphorous compound or a sulfur compound
Implementation Method 2
A coating layer containing phosphorous or sulfur compounds is used, which suppresses the decomposition of the non-aqueous electrolyte
Data Source
AI summary
A non-aqueous electrolyte battery includes a container, a positive electrode housed in the container, a negative electrode housed in the container with a space from the positive electrode and containing an active material, and a non-aqueous electrolyte housed in the container. The active material includes a lithium-titanium composite oxide particle and a coating layer formed on at least a part of the surface of the particle, the coating layer being contained at least one element selected from the group consisting of phosphorous and sulfur or a phosphorous compound or a sulfur compound.