Solid-State Battery Anode Gradient for Lower Resistance
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Solution Overview
Problem
Lithium titanate anode active materials exhibit a large plateau region in charge and discharge curves, leading to increased resistance due to electrode reactions deviating in the thickness direction of the anode active material layer.
Innovation Solution
An all solid state battery design incorporating a first anode active material (lithium titanate) with a specified second anode active material, such as niobium-titanium oxide, where the proportion of lithium titanate is relatively less near the solid electrolyte layer and more distant from it, mitigating electrode reaction deviation and reducing resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium titanate is used as anode active material, then safety is improved due to solid electrolyte, but resistance increases due to electrode reaction deviation in thickness direction
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of lithium titanate particles within the anode active material layer. Specifically, the concentration of lithium titanate particles varies through the thickness of the layer, with different regions having different proportions of lithium titanate compared to other anode active materials. This localized variation in composition allows the electrode reactions to occur more uniformly across the thickness direction, reducing resistance while maintaining the safety benefits of lithium titanate.
2Ease of manufacture
If uniform distribution of lithium titanate is used in anode active material layer, then manufacturing is simplified, but electrode reaction deviation increases leading to higher resistance
Solution Approach 1:
The patent implements local quality by specifying that the anode active material layer contains regions with different lithium titanate concentrations. The proportion of lithium titanate particles is controlled to be different in the thickness direction, creating a gradient structure that optimizes electrochemical performance while managing the complexity of manufacturing through defined compositional zones.
Solution Approach 2:
The patent applies parameter changes by varying the concentration parameter of lithium titanate particles through the thickness of the anode active material layer. This parameter variation (from higher concentration near one interface to lower concentration near the other interface) modifies the electrochemical behavior to reduce reaction deviation and resistance, while still being manufacturable through controlled processing parameters.
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 battery achieves low resistance and excellent rate properties by minimizing electrode reaction deviation through strategic distribution of lithium titanate and niobium-titanium oxide, enhancing ion and electron conductivity.
Implementation Method 1
a solid electrolyte layer arranged between the cathode active material layer and the anode active material layer
Implementation Method 2
electrode reactions tend to deviate in the thickness direction of the anode active material layer
Data Source
AI summary
A main object of the present disclosure is to provide an all solid state battery with low resistance. The present disclosure achieves the object by providing an all solid state battery comprising a cathode active material layer, an anode active material layer, and a solid electrolyte layer arranged between the cathode active material layer and the anode active material layer; wherein the anode active material layer includes: a first anode active material and a second anode active material; the first anode active material is a lithium titanate; in the second anode active material, when a discharge capacity at a potential of 1.0 V vs Li+/Li or more and 2.0 V vs Li+/Li or less signifies 100% discharge capacity, and when P1 designates an average potential in a capacity of 0% or more and 50% or less of the 100% discharge capacity, and P2 designates an average potential in a capacity of 50% or more and 100% or less of the 100% discharge capacity, a difference between the P2 and the P1 is 0.1 V or more; and when T designates a thickness of the anode active material layer, X designates a region of the anode active material layer that is from an edge of the solid electrolyte layer side to T/2 in a thickness direction, Y designates a region of the anode active material layer that is from the T/2 to an opposite edge from the solid electrolyte layer side in the thickness direction, X1 designates a volume ratio of the first anode active material with respect to a total of the first anode active material and the second anode active material in the X, and Y1 designates a volume ratio of the first anode active material with respect to a total of the first anode active material and the second anode active material in the Y, the X1 is smaller than the Y1.