Niobium-Titanium Oxide Anode Particles for Fast-Charge Energy Density
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Solution Overview
Problem
Secondary batteries with carbon-based negative electrodes face issues such as dendrite precipitation, heat generation, and fires due to internal short circuits during rapid charge-and-discharge, while titanium oxide-based batteries have lower energy density and capacity due to their noble potential and limited lithium insertion sites.
Innovation Solution
An active material comprising niobium-containing oxide particles with protruded and recessed parts, specifically niobium-titanium composite oxides like Nb2TiO7, is used to enhance electrode performance, allowing for stable rapid charge-and-discharge and increased energy density by optimizing the shape and distribution of particles to improve electrolyte retention and lithium ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If titanium oxide is used as negative electrode material to enable rapid charge-and-discharge, then charge-and-discharge performance is improved, but energy density decreases due to higher potential and lower capacity per weight
Solution Approach 1:
The patent uses a composite oxide material containing both titanium and niobium elements (such as Nb2TiO7, Li2Nb2TiO7, or LiNb2TiO7) to combine the advantages of both materials. The titanium component provides rapid charge-and-discharge capability, while the niobium component increases capacity per weight, achieving both high productivity and high energy density simultaneously
Solution Approach 2:
The patent modifies the chemical composition parameters by controlling the molar ratios of titanium to niobium (specifically 1:2 to 1:4 ratios) and adjusting lithium content to create optimal composite structures that balance potential, capacity, and energy density for both rapid charge-and-discharge and high energy storage
2Use of energy by moving object
If electrode density is increased to improve energy density, then energy density is improved, but input/output performance deteriorates causing shortened charge-and-discharge life
Solution Approach 1:
The patent creates particles with non-spherical shapes featuring protruded and recessed parts, where the recessed parts specifically serve to retain electrolyte locally. This local structural feature ensures that even at high electrode densities, the electrolyte is retained at critical particle surfaces, maintaining good input/output performance while achieving high energy density
Solution Approach 2:
The patent utilizes particles with surface recesses that create porous-like structures for electrolyte retention. These recessed parts act as electrolyte reservoirs, ensuring continuous ion transport pathways are maintained even when particles are densely packed in the electrode, thus preserving input/output performance at high densities
3Quantity of substance
If carbon-based negative electrode is used to achieve high capacity, then capacity per weight is improved, but dendrite precipitation and safety issues occur during rapid charge-and-discharge
Solution Approach 1:
The patent converts the harmful effect of lithium instability into a benefit by using composite oxide materials that provide stable lithium insertion/extraction sites. The niobium-titanium composite structure creates ordered pathways for lithium ions, transforming the chaotic lithium deposition that causes dendrites into controlled, reversible lithium insertion, maintaining safety while achieving rapid charge-and-discharge capability
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 niobium-containing oxide particles with tailored shapes and structures enable high energy density, excellent rapid charge-and-discharge performance, and extended battery life by facilitating uniform lithium ion diffusion and maintaining electrolyte retention, thus addressing the limitations of previous materials.
Implementation Method 1
lithium is easily stabilized in the structure, whereby the substantial capacity decreases
Implementation Method 2
the recessed parts serve to retain the electrolyte
Data Source
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AI summary
In general, according to one approach, an active material including particles containing a niobium-containing oxide is provided. The particles containing the niobium-containing oxide contain single particles (394) (501, 503, or 505) having protruded parts and recessed parts (502, 504). Three or more of the recessed parts (502, 504) satisfy 0.1 ≤ a/L ≤ 0.5 (1). Where L is a length of a tangent line in contact with a first protruded part (501, 505) and a second protruded part (503), and a is a maximum length of a perpendicular line from the tangent line to a recessed part (502, 504) defined by the first protruded part (501, 505) and the second protruded part (503).