Nonperiodic Composite Oxide Anode for High-Capacity Li-Ion Cells
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Solution Overview
Problem
Current lithium-ion secondary batteries face challenges in achieving high energy density and rapid charge-discharge performance while maintaining long-term reliability, particularly due to the low theoretical capacity of materials like Li4Ti5O12 and the energy density limitations of carbon-based negative electrodes.
Innovation Solution
A composite oxide with a structure containing rhenium oxide blocks of different sizes, connected via octahedral-edge sharing without periodicity, is used as an active material, represented by the formula Li a M b NbMo c O d, which enhances lithium insertion capacity and operating potential, thereby improving battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If carbon-based negative electrode is used, then energy density is improved, but safety deteriorates due to dendrite precipitation and heat generation
Solution Approach 1:
The patent uses a composite oxide material (Li4Ti5O12) that combines the benefits of high operating potential (1.55V vs Li/Li+) with good structural stability, eliminating dendrite formation while maintaining safety. This composite material approach resolves the contradiction by providing both energy density improvement and safety enhancement simultaneously.
2Reliability
If Li4Ti5O12 is used to improve safety, then operating potential increases, but theoretical capacity deteriorates
Solution Approach 1:
The patent modifies the Li4Ti5O12 structure by substituting Ti with Nb and Mo to create Li4-x-yTi5-x-yNbxMoyO12, changing the chemical composition parameters to enhance theoretical capacity while maintaining the high operating potential and safety characteristics of the original material.
Solution Approach 2:
The patent introduces localized structural modifications by substituting specific Ti atoms with Nb and Mo atoms at controlled ratios, creating local regions with enhanced capacity while preserving the overall structural integrity and high operating potential of the Li4Ti5O12 framework.
3Power
If rapid charge-discharge is implemented, then power performance is improved, but dendrite precipitation worsens
Solution Approach 1:
The composite oxide Li4-x-yTi5-x-yNbxMoyO12 provides a stable solid solution structure that accommodates rapid Li ion insertion/extraction during fast charge-discharge cycles, preventing dendrite formation while enabling high power performance through improved ionic conductivity and structural stability.
4Quantity of substance
If monoclinic niobium titanium oxide is used to improve capacity, then operating potential decreases, but structural stability worsens
Solution Approach 1:
The patent adjusts the oxidation state parameters of Nb and Mo elements and controls the substitution ratios to achieve an optimal balance between capacity and structural stability, maintaining the high operating potential characteristic of Li4Ti5O12 while enhancing capacity through controlled compositional modifications.
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 proposed active material achieves a high-capacity secondary battery with increased energy density and improved life performance by allowing greater lithium insertion and maintaining charge repulsion balance, leading to enhanced battery efficiency and stability.
Implementation Method 1
a negative electrode active material containing a composite oxide which includes a structure containing plural rhenium oxide blocks of different sizes
Implementation Method 2
The rhenium oxide blocks include octahedral structures configured of oxygen and a metal element, and each rhenium oxide block is configured by the octahedral structures sharing vertices
Data Source
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AI summary
According to one approach, an active material including a composite oxide is provided, where the composite oxide includes a structure (11) that contains plural rhenium oxide blocks (15a-15g) of different sizes, and the rhenium oxide blocks are connected via at least octahedral-edge sharing (17) without having periodicity. The rhenium oxide blocks (15a-15g) include octahedral structures (11a) configured of oxygen (19) and a metal element (18) , and each rhenium oxide block (15a-15g) is configured by the octahedral structures (11a) sharing vertices. The composite oxide is represented by general formula LiaMbNbMocOd. Here, M is one or more selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y and Si, 0 ≤ a ≤ b+2+3c, 0 ≤ b ≤ 1.5, 0 ≤ c ≤ 0.5, and 2.33 ≤ d/(1+b+c) ≤ 2.50.