Oxyfluoride-Coated Battery Active Material for Cycle Stability
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries face capacity deterioration due to repeated charge and discharge cycles, despite surface modifications with zirconium hydroxide or zirconium oxide and lithium salts.
Innovation Solution
An active material with a lithium-containing composite oxide core coated with an oxyfluoride salt, represented by the formula M1OFa (2≤a≤6, where M1 is Ti, Zr, Si, or B, inhibits side reactions and improves charge-discharge cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface modification with zirconium hydroxide or zirconium oxide and lithium salts is applied, then charge-discharge cycle characteristics are improved, but battery capacity deterioration still occurs due to side reactions with electrolyte
Solution Approach 1:
The patent applies a composite coating structure consisting of two distinct layers: an inner layer of zirconium hydroxide or zirconium oxide with lithium salts (from prior art) and an outer layer of oxyfluoride salt (new addition). This composite structure combines the benefits of both materials - the inner layer provides base protection while the outer oxyfluoride layer specifically inhibits side reactions with electrolyte, thereby resolving the contradiction between improving cycle characteristics and preventing harmful side reactions.
Solution Approach 2:
The patent creates different functional zones within the coating layer by positioning specific materials at different locations. The inner layer (zirconium-based) provides general surface modification, while the outer layer (oxyfluoride) specifically targets the interface with electrolyte to prevent side reactions. This local differentiation of material properties allows simultaneous achievement of cycle stability and reaction inhibition.
2Duration of action of stationary object
If conventional surface modification methods are used, then some improvement in cycle characteristics is achieved, but battery capacity deteriorates after repeated charge and discharge
Solution Approach 1:
The patent applies surface modification with the dual-layer coating structure before the battery undergoes repeated charge and discharge cycles. This preliminary protective action creates a stable interface between the active material and electrolyte in advance, preventing capacity deterioration from occurring in the first place rather than attempting to restore it after damage occurs. The oxyfluoride layer specifically prepares the surface to resist electrolyte decomposition before cycling begins.
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 oxyfluoride coating effectively prevents battery capacity deterioration, maintaining performance even after repeated charge and discharge cycles by reducing side reactions and electrolyte decomposition.
Implementation Method 1
a salt adhering to a surface of the core, wherein the salt includes an oxyfluoride represented by the general formula M1OFa
Implementation Method 2
the salt including an oxyfluoride... inhibits side reactions and improves charge-discharge cycle characteristics
Implementation Method 3
a core that is able to reversibly occlude and release Li
Implementation Method 4
the oxyfluoride coating effectively prevents battery capacity deterioration... by reducing side reactions and electrolyte decomposition
Data Source
AI summary
Provided is an active material contributing to improving the charge/discharge cycle characteristics of a battery. This active material for a non-aqueous electrolyte secondary battery includes: a core capable of reversible intercalation and deintercalation of Li; and a salt attached to the surface of the core, wherein the salt comprises an oxyfluoride represented by general formula M1OFa (2≤a≤6, M1 is at least one element selected from the group consisting of Ti, Zr, Si, P, and B).