Spinel Negative Electrode Active Material for High Temperature Cycle Life
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Solution Overview
Problem
Lithium ion batteries used in vehicles face challenges with high temperature durability, low temperature performance, and cycle life due to inadequate chemical and electrochemical stability, corrosion resistance, and large particle size of active materials, which limits their capacity, output, and reliability.
Innovation Solution
A negative electrode active material represented by Li2+aAdTi6−bBbO14−c, where A is selected from Na, K, Mg, Ca, Ba, and Sr, and B is a metal element, with a carbon material coating to enhance electron conductivity and reduce interface resistance, improving high temperature cycle life and large current discharge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the negative electrode is decreased to increase the density, then the capacity increases, but the current collector has insufficient strength, limiting battery capacity, output performance, cycle life, and reliability
Solution Approach 1:
The invention changes the physical and chemical parameters of the negative electrode active material by using a specific spinel structure (Li2+aAdTi6-bBbO14-c) with controlled composition ratios and particle sizes (0.3-2.0 μm). This structural parameter change enables the material to maintain high capacity while providing sufficient mechanical strength to the current collector, resolving the contradiction between capacity and structural integrity.
2Reliability
If the particle size of the negative electrode active material is increased to improve high temperature durability, then the thermal stability improves, but the interface resistance of the electrode increases, making it more difficult to exploit high performance
Solution Approach 1:
The invention optimizes the particle size parameter to a specific range (0.3-2.0 μm) and controls the composition parameters (a, b, c values) of the spinel structure. This parameter optimization achieves a balance where particles are large enough to provide thermal stability but small enough to maintain low interface resistance, resolving the contradiction between high temperature durability and electrode performance.
Solution Approach 2:
The invention uses a composite spinel structure (Li2+aAdTi6-bBbO14-c) combining multiple elements (Ti, B, and other metal elements) to create a material with both high thermal stability and low interface resistance. The composite nature of the material allows simultaneous achievement of high temperature durability and low resistance, resolving the technical contradiction.
3Temperature
If lithium iron phosphate or lithium manganese phosphate is used as positive electrode active material to improve thermal stability, then the thermal stability improves, but the electrical conductivity is low, causing problems in charge-and-discharge rate performance
Solution Approach 1:
The invention uses a spinel-based negative electrode active material with high electrical conductivity as an intermediary to compensate for the low electrical conductivity of lithium iron phosphate or lithium manganese phosphate positive electrode materials. The spinel material's superior conductivity facilitates electron transport, resolving the contradiction between thermal stability and charge-discharge rate performance in the overall battery system.
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 improved high temperature cycle life and large current discharge performance without significantly decreasing discharge capacity, enhancing the reliability and efficiency of lithium ion batteries in vehicles.
Implementation Method 1
with a carbon material coating to enhance electron conductivity and reduce interface resistance
Data Source
AI summary
According to one embodiment, a negative electrode active material includes particles and a carbon material. The particles is represented by Li2+aAdTi6−bBbO14−c, where A is at least one element selected from the group consisting of Na, K, Mg, Ca, Ba, and Sr; B is a metal element other than Ti; and a, b, c, and d respectively satisfy 0≤a≤5, 0≤b≤6, 0≤c≤0.6, and 0≤d≤3. The carbon material covers at least a part of surfaces of the particles.