Rock-Salt Positive Electrode Material for Solid-State Battery Volume Stability
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Solution Overview
Problem
Conventional lithium secondary batteries experience a decrease in charge-discharge efficiency due to volume contraction of the positive electrode active material, leading to reduced energy density, as the contact area between the positive electrode and the solid electrolyte changes during charge and discharge.
Innovation Solution
A battery configuration using a positive electrode active material with a rock-salt crystal structure represented by the formula LixMeyOαFβ, where Me includes various metals and the ratios of x, y, α, and β are optimized to maintain a stable structure, ensuring minimal volume change and thus maintaining a high contact area with the solid electrolyte, enhancing charge-discharge efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode active material is used, then battery structure is simple, but volume contraction occurs during charge leading to reduced contact area with solid electrolyte and decreased charge-discharge efficiency
Solution Approach 1:
The patent changes the crystal structure parameter from layered to rock-salt type, and optimizes the chemical composition parameters (x, y, α, β in formula LixMeyOαFβ) to achieve a stable rock-salt structure that maintains constant volume during charge-discharge cycles, resolving the volume contraction problem
Solution Approach 2:
The patent uses composite material strategy by combining multiple metal elements (Me = Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, Cr) in specific ratios to create a stable rock-salt type positive electrode active material with enhanced structural stability
2Productivity
If rock-salt type positive electrode active material is used, then charge-discharge efficiency is improved, but manufacturing complexity increases due to precise composition control requirements
Solution Approach 1:
The patent defines specific parameter ranges (1.7≤x≤2.2, 0.8≤y≤1.3, 1≤α≤2.5, 0.5≤β≤2) that provide a manufacturing window for achieving the desired rock-salt structure, balancing performance requirements with manufacturability
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
This configuration results in a battery with higher energy density and capacity, as the stable rock-salt structure allows for efficient lithium intercalation and deintercalation without structural disruption, maintaining a large contact area and hence high charge-discharge efficiency.
Implementation Method 1
efficient lithium intercalation and deintercalation without structural disruption
Data Source
AI summary
A battery includes a positive electrode containing a positive electrode active material, a negative electrode, and a solid electrolyte. The positive electrode active material contains a compound which has a crystal structure belonging to the space group FM3-M and which is represented by the following formula:LixMeyOαFβ (1)where Me is one or more selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V and Cr and the conditions 1.7≤x≤2.2, 0.8≤y≤1.3, 1≤α≤2.5, and 0.5≤β≤2 are satisfied.