Niobium-Titanium Core Shell Battery Anode
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Solution Overview
Problem
Nonaqueous electrolyte batteries face challenges in achieving high energy density and safety due to the limitations of titanium oxide negative electrodes, which have low capacity and are prone to internal short-circuits during rapid charge-and-discharge cycles.
Innovation Solution
The development of an active material comprising monoclinic or orthorhombic niobium-titanium composite oxide particles with a shell layer of lithium-titanium composite oxide or lithium phosphate, which enhances lithium insertion capacity and prevents short-circuit currents by reducing electron conductivity during high state-of-charge conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If titanium oxide is used as the negative electrode active material to enable rapid charge-and-discharge, then the battery can perform rapid charge-and-discharge cycles, but the capacity per weight is low and energy density is reduced
Solution Approach 1:
The patent uses a composite structure of titanium oxide core particles coated with a lithium-containing compound shell. The titanium oxide core provides rapid charge-and-discharge capability, while the lithium-containing compound shell increases the capacity per weight, thereby resolving the contradiction between rapid charge-and-discharge performance and capacity per weight.
2Productivity
If titanium oxide is used as the negative electrode active material, then rapid charge-and-discharge can be performed, but dendrite deposition occurs causing internal short-circuits and safety risks
Solution Approach 1:
The patent applies a protective shell layer of lithium-containing compound on the titanium oxide core particles before dendrite formation can occur. This shell acts as a cushioning barrier that prevents dendrite deposition and internal short-circuits, thereby maintaining safety while preserving rapid charge-and-discharge performance.
3Reliability
If the electrode potential of titanium oxide is maintained at about 1.5 V to ensure stable rapid charge-and-discharge, then electrochemical stability is achieved, but energy density cannot be improved
Solution Approach 1:
The patent creates a composite material where the titanium oxide core maintains the stable electrode potential of about 1.5 V for electrochemical stability, while the lithium-containing compound shell contributes additional capacity. This composite structure allows the battery to maintain electrochemical stability while improving energy density through the combined effects of both materials.
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
This configuration results in a nonaqueous electrolyte battery with improved capacity, safety, and extended cycle life by stabilizing lithium ion insertion and extraction, while preventing heat generation from short-circuit events.
Implementation Method 1
charge compensation, in which tetravalent Ti is turned into trivalent Ti, and pentavalent Nb is turned into trivalent Nb, is caused upon the Li insertion
Implementation Method 2
prevents short-circuit currents by reducing electron conductivity during high state-of-charge conditions
Implementation Method 3
preventing heat generation from short-circuit events
Data Source
AI summary
According to one embodiment, an active material is provided. The active material includes active material particles. The active material particle includes a core particle and a shell layer which covers at least a part of a surface of the core particle. The core particle contains a monoclinic or orthorhombic niobium-titanium composite oxide. The shell layer contains a compound which is at least one compound selected from the group consisting of a lithium-titanium composite oxide, an Nb-containing lithium-titanium composite oxide, a lithium-niobium composite oxide, a lithium phosphate, and an Nb-containing lithium phosphate. The compound has a composition different from that of the monoclinic or orthorhombic niobium-titanium composite oxide.