Carbon-Coated Niobium Titanium Oxide Anode for Fast-Charging Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Secondary batteries using carbon-based negative electrodes face issues with rapid charge-discharge leading to metallic lithium dendrite precipitation, heat generation, and low energy density due to insufficient electronic conductivity and capacity, while titanium oxide electrodes offer stability but low energy density and capacity.
Innovation Solution
A niobium titanium-containing oxide phase with a monoclinic structure and a carbon coating layer containing carboxyl groups is used, which enhances electronic conductivity and adsorbs metal ions, improving storage performance and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon-based negative electrode is used, then capacity per weight is improved, but metallic lithium dendrite precipitation occurs during rapid charge-discharge
Solution Approach 1:
A carbon coating layer is introduced as an intermediary between the fibrous carbon and the electrolyte. This carbon layer mediates the interaction by providing a stable interface that prevents direct contact between lithium ions and fibrous carbon, thereby suppressing dendrite formation while maintaining high capacity
Solution Approach 2:
The negative electrode uses a composite structure combining fibrous carbon (for high capacity) with a carbon coating layer (for stability and dendrite prevention). This composite material approach allows the system to achieve both high capacity per weight and resistance to dendrite precipitation
2Reliability
If oxide of titanium is used in negative electrode, then rapid charge-discharge stability is improved, but energy density decreases
Solution Approach 1:
The invention changes the key parameter from electrode material composition to electrode structure morphology. By using fibrous carbon with specific surface area control and carbon coating, the system achieves rapid charge-discharge stability through improved ion transport pathways rather than relying on titanium oxide's inherent stability
Solution Approach 2:
The carbon coating layer is applied locally on the surface of fibrous carbon particles, creating a gradient structure where the interior maintains high capacity characteristics while the surface provides stability. This local modification allows simultaneous achievement of high energy density and rapid charge-discharge stability
3Quantity of substance
If niobium titanium-containing oxide is used, then charge-discharge capacity is improved, but electronic conductivity decreases
Solution Approach 1:
The negative electrode employs a composite of fibrous carbon (providing electronic conductivity network) and amorphous carbon coating layer (providing additional conductive pathways). This composite structure ensures high electronic conductivity while maintaining the high charge-discharge capacity enabled by the fibrous morphology and surface area
4Loss of energy
If conventional carbon coating is used, then electronic conductivity is improved, but metal ion adsorption capability decreases
Solution Approach 1:
The carbon coating layer is designed with non-uniform properties: the bulk provides electronic conductivity while the surface possesses metal ion adsorption capability. This local differentiation of properties within the same coating layer allows simultaneous achievement of both functions
Solution Approach 2:
The invention changes the surface chemistry parameters of the carbon coating by controlling surface area and introducing surface functional groups. This parameter modification enables the carbon coating to exhibit metal ion adsorption capability while maintaining its electronic conductivity function
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 solution provides a secondary battery with improved rapid charge-discharge performance, extended cycle life, and enhanced energy density by maintaining electronic conductivity and reducing self-discharge, while allowing the use of inexpensive fibrous carbon and minimizing metal ion elution.
Implementation Method 1
A niobium titanium-containing oxide phase with a monoclinic structure and a carbon coating layer containing carboxyl groups is used, which enhances electronic conductivity
Implementation Method 2
The carbon coating layer containing carboxyl groups is used, which enhances electronic conductivity and adsorbs metal ions
Implementation Method 3
rapid charge and discharge can be stably performed at a high electrode potential of about 1.5 V (vs. Li/Li+)
Implementation Method 4
The potential of an oxide of titanium is electrochemically restricted due to being caused by oxidation-reduction reactions between Ti3+ and Ti4+ upon insertion and extraction of lithium
Data Source
AI summary
According to one embodiment, provided is an active material including a niobium titanium-containing oxide phase and a carbon coating layer. The niobium titanium-containing oxide phase contains a niobium titanium-containing oxide having a monoclinic structure and Na, and a Na content therein is 0 ppm or more and 100 ppm or less. The carbon coating layer coats at least a part of the niobium titanium-containing oxide phase, and contains 0.001% or more of carboxyl group.