TiNb2O7 Active Material for High-Rate Lithium-Ion Batteries
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Solution Overview
Problem
Nonaqueous electrolyte batteries, particularly lithium-ion batteries, face challenges with rapid charge/discharge performance and energy density due to dendrite formation and the limitations of carbon-based negative electrodes, which lead to internal short circuits and low energy storage capacity.
Innovation Solution
The development of active material particles with a monoclinic TiNb2O7 structure, represented by the formula Ti1-xM1xNb2-yM2yO7, which suppresses crystal growth on difficult-to-diffuse planes, enhancing lithium ion insertion stability and capacity, and using a carbon coating to improve conductivity and prevent surface reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbonaceous material is used as negative electrode active material, then capacity per weight is high, but dendrite precipitation occurs during rapid charge/discharge
Solution Approach 1:
A lithium phosphate coating layer is applied as an intermediary between the carbonaceous material and the electrolyte. This coating layer prevents direct contact and harmful reactions while allowing lithium ion transport, thereby suppressing dendrite precipitation during rapid charge/discharge cycles while maintaining the high capacity characteristics of carbonaceous materials
Solution Approach 2:
The surface chemistry and physical properties of the carbonaceous material are modified by coating it with lithium phosphate. This changes the interface parameters between the electrode and electrolyte, creating a stable solid electrolyte interface that prevents dendrite formation while maintaining ion conductivity for high-rate performance
2Productivity
If titanium oxide is used as negative electrode active material, then rapid charge/discharge performance is improved, but energy density decreases
Solution Approach 1:
The patent uses a composite structure combining carbonaceous material (providing high capacity) with lithium phosphate coating (providing rapid ion transport and dendrite suppression). This composite approach achieves both high energy density from the carbon material and excellent rapid charge/discharge performance from the optimized interface, eliminating the need to use titanium oxide which has lower energy density
3Reliability
If lithium phosphate coating is applied to carbonaceous material, then dendrite precipitation is suppressed, but manufacturing complexity increases
Solution Approach 1:
The coating process optimizes parameters such as coating thickness, composition ratio, and formation conditions to achieve effective dendrite suppression with minimal additional manufacturing steps. The lithium phosphate coating can be applied through conventional battery manufacturing processes, maintaining production efficiency while improving reliability
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 enables high-capacity, high-rate performance batteries with improved rapid charge and discharge characteristics and increased energy density by facilitating lithium ion diffusion and maintaining structural stability.
Implementation Method 1
The potential of titanium oxide is due to the redox reaction between Ti3+ and Ti4+ when lithium is electrochemically inserted and released
Implementation Method 2
facilitating lithium ion diffusion and maintaining structural stability
Implementation Method 3
The potential of titanium oxide is due to the redox reaction between Ti3+ and Ti4+ when lithium is electrochemically inserted and released
Implementation Method 4
using a carbon coating to improve conductivity and prevent surface reactions
Data Source
AI summary
According to one embodiment, there is provided an active substance. The active substance contains active material particles. The active material particles comprise a compound represented by the formula: Ti1-xM1xNb2-yM2yO7. The active material particles has a peak A attributed to a (110) plane which appears at 2θ ranging from 23.74 to 24.14°, a peak B attributed to a (003) plane which appears at 2θ ranging from 25.81 to 26.21° and a peak C attributed to a (602) plane which appears at 2θ ranging from 26.14 to 26.54° in an X-ray diffraction pattern of the active material particles. An intensity IA of the peak A, an intensity IB of the peak B, and an intensity IC of the peak C satisfy the relation (1): 0.80≤IB/IA≤1.12; and the relation (2) IC/IB≤0.80.