Nb-Ti Complex Oxide Anode for High Energy Density Batteries
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Solution Overview
Problem
Nonaqueous electrolyte batteries face challenges in achieving high energy density and rapid charge/discharge performance due to limitations in titanium-based oxide materials, which have low capacity per mass and limited lithium ion insertion sites, leading to reduced energy density and stability concerns.
Innovation Solution
A complex oxide material containing Nb and Ti with specific molar ratios and a monoclinic crystal structure, along with the addition of elements like Mo and Mg, is developed to enhance lithium ion conductivity and insertion capacity, achieving a higher theoretical capacity and improved energy density while maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If titanium based oxide is used as negative electrode active material, then rapid charge/discharge performance is improved, but energy density decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the titanium-based oxide by incorporating multiple metal elements (V, Mn, Fe, Co, Ni, Mo, Ir) to replace部分Ti atoms, thereby modifying the crystal structure and increasing the number of lithium insertion sites while maintaining the rapid charge/discharge capability
Solution Approach 2:
The patent creates a composite oxide material with the general formula MxTi1-xO2, combining titanium oxide with other metal oxides to achieve synergistic effects that simultaneously improve capacity and maintain fast ion transport properties
2Quantity of substance
If complex oxide TiNb2O7 is used to increase capacity, then theoretical capacity exceeds 300 mAh/g, but productivity decreases
Solution Approach 1:
The patent optimizes the sintering temperature parameter to 900-1100°C, which is lower than conventional methods, thereby reducing energy consumption and production time while achieving high crystallinity and desired capacity
Solution Approach 2:
The patent introduces element M with specific properties (ionic radius 0.04-0.13 nm) to locally modify the crystal structure, creating favorable sites for lithium insertion without requiring complete restructuring of the entire material system
3Reliability
If titanium based oxide is used, then potential is about 1.5V based on metal lithium, but capacity per mass is lower than carbonaceous material
Solution Approach 1:
The patent modifies the stoichiometric ratio of metals in the oxide by controlling the parameter x in MxTi1-xO2, optimizing the balance between stability (maintained by TiO2 framework) and capacity (enhanced by other metal elements)
Solution Approach 2:
The patent designs a multi-functional material that simultaneously provides structural stability from TiO2, high capacity from other metal elements, and fast ion transport from the preserved rutile/anatase crystal structure
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 complex oxide material provides superior rapid charge/discharge performance and high energy density, with a theoretical capacity of about 387 mAh/g, twice that of Ti oxide with a spinel structure, and a melting point reduced to enable high crystallinity at lower sintering temperatures, improving productivity.
Implementation Method 1
The potential of titanium based oxide is due to the redox reaction between Ti 3+ and Ti 4+.
Implementation Method 2
a melting point reduced to enable high crystallinity at lower sintering temperatures
Data Source
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AI summary
According to one embodiment, a battery active material includes a complex oxide containing Nb and Ti and an element M. In the active material, the molar ratio (M/Ti) of the element M to Ti satisfies the following formula (I): 0 < M/Ti ≤ 0.5 (I). In the complex oxide containing Nb and Ti, the molar ratio (Nb/Ti) of Nb to Ti satisfies the following formula (II): 0 ≤ Nb/Ti ≤ 5 (II), The element M is at least one selected from the group consisting of B, Na, Mg, Al, Si, S, P, K, Ca, Mo, W, Cr, Mn, Co, Ni, and Fe.