Monoclinic Complex Oxide Battery Electrode for Fast Charging
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Solution Overview
Problem
Nonaqueous electrolyte batteries, particularly those with carbon-based negative electrodes, face issues with dendrite formation and low energy density during quick charge and discharge cycles, leading to reduced performance and safety concerns.
Innovation Solution
A monoclinic complex oxide with a specific crystal structure, expressed by the formula Li x M1M2 2 O (7±δ), is used as the active material, where M1 includes Ti, Zr, or Sn, and M2 includes Nb, V, Ta, Bi, or Mo, with controlled occupancy in the crystal sites, enhancing lithium ion mobility and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a carbon-based negative electrode is used, then the capacity for unit weight is high, but dendrites deposit on the electrode during quick charge and discharge, causing heat generation and ignition
Solution Approach 1:
The patent changes the material parameter from carbon-based to metal complex oxide (titanium oxide), which has different electrochemical properties including higher potential stability and no dendrite formation, though this reduces capacity for unit weight
Solution Approach 2:
The patent uses a composite electrode structure combining titanium oxide (for safety and stability) with conductive materials like carbon black and graphite to compensate for the lower capacity, creating a balanced composite material that achieves both safety and acceptable performance
2Reliability
If titanium oxide is used as the negative electrode, then stable and quick charge and discharge is achieved, but the energy density is low due to higher potential and lower capacity for unit weight
Solution Approach 1:
The patent modifies the titanium oxide material parameters by controlling particle size (1-10 μm) and using specific crystal structures (anatase, rutile, or amorphous forms) to optimize both the stability and capacity properties
Solution Approach 2:
The patent creates composite materials combining titanium oxide with carbon-based conductive materials and binders to enhance the overall energy density while maintaining the electrochemical stability of titanium oxide
3Duration of action of stationary object
If titanium oxide is used as the negative electrode, then the life is longer, but the capacity for unit weight is low due to fewer lithium occlusion sites and easy lithium stabilization
Solution Approach 1:
The patent changes physical parameters of titanium oxide including particle size reduction to 1-10 μm and control of crystalline structure to increase the number of available lithium occlusion sites while maintaining structural stability for long cycle life
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 monoclinic complex oxide enables stable and high-rate performance with increased energy density, reducing dendrite formation and improving charge/discharge efficiency, while being suitable for both negative and positive electrodes.
Implementation Method 1
The potential of titanium oxide is attributable to the oxidation-reduction reaction between Ti 3+ and Ti 4+.
Implementation Method 2
TiO2 and Nb2O5 were mixed and milled in a ball-mill.
Implementation Method 3
a pellet of the resulting powder was heated at 1350°C for 24 h
Implementation Method 4
The sintered product is annealed at a temperature lower than 1000°C
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
In general, according to one embodiment, an active material for battery includes a monoclinic complex oxide. The monoclinic complex oxide is expressed by the general formula LixM1M22O(7±δ) (wherein M1 is at least one element selected from the group consisting of Ti, Zr, Si, and Sn, M2 is at least one element selected from the group consisting of Nb, V, Ta, Bi, and Mo, 0 ≤ x ≤ 5, and 0 ≤ δ ≤ 0.3), and has symmetry belonging to the space group C2/m (International tables Vol. A No. 12), and one element of the M2 or M1 being maldistributed in the occupied 2a and 4i sites in a crystal of the monoclinic complex oxide.