Composite Battery Active Material for High Capacity and Conductivity
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Solution Overview
Problem
The lifetime characteristics of existing active materials for secondary batteries are insufficient, necessitating an improvement in their performance across various charge-discharge rates and temperatures.
Innovation Solution
A combination of a 5 V-class spinel active material represented by the formula Lip[M1mM22-m-nM3n]O4 and a layered structure active material represented by Liq[LiaXxZzMn1-a-x-z]O2, where M1 includes Ni, Cr, Fe, or Cu, M2 includes Mn or Si, and M3 includes Li, B, Mg, Al, Na, or Ca, is used to enhance the battery's capacity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a layered structure active material (LiMO2) is used to achieve high capacity (200 mAh/g or more), then the charge-discharge capacity is improved, but the ion conductivity and electron conductivity are low, causing capacity decrease at low temperatures and high charge-discharge rates
Solution Approach 1:
The patent combines a spinel compound (providing high ion conductivity) with a layered structure compound (providing high capacity) to create a composite active material. This composite structure allows the material to simultaneously achieve high charge-discharge capacity and high ion conductivity, resolving the contradiction between capacity and conductivity.
2Power
If LiCoO2 is used as the active material, then the operating potential is sufficient (3.6-3.8 V), but the safety in charged state is not always sufficient and the price of Co raw material is high
Solution Approach 1:
The patent changes the chemical composition parameters by using a spinel compound with specific metal element ratios (Ni, Mn, Co, Al) to achieve high operating potential (4.2-4.8 V) while improving safety characteristics. The spinel structure provides inherent stability that enhances safety in charged state compared to conventional LiCoO2.
3Use of energy by moving object
If spinel compound (LiNi0.5Mn1.5O4) is used to achieve 5 V-class operating potential and high ion conductivity, then the energy density is improved, but the capacity is lower compared to layered structure materials
Solution Approach 1:
The patent creates a composite material combining spinel compound and layered structure compound in specific ratios. The spinel component provides high ion conductivity and 5V-class potential, while the layered component contributes high capacity. The synergistic combination achieves both high energy density and high capacity.
Solution Approach 2:
The patent optimizes the local composition by controlling the ratio of spinel to layered structure compounds, and by adjusting metal element ratios within each phase. This local quality optimization allows different regions of the composite material to contribute their strengths, achieving balanced performance in both energy density and capacity.
4Quantity of substance
If Ni-containing layered structure materials (LiNiO2, Li[Ni0.8Co0.2]O2) are used to achieve high discharge capacity (about 200 mAh/g), then the capacity is improved, but the crystal stability when charged is low
Solution Approach 1:
The patent combines Ni-containing layered structure material (providing high discharge capacity) with spinel compound (providing structural stability). The spinel phase acts as a stabilizing component that maintains crystal structure integrity during charging, while the layered phase delivers high capacity.
Solution Approach 2:
The patent modifies the composition parameters by controlling Ni content and adding other metal elements (Co, Mn, Al) in specific ratios. This parameter optimization reduces the harmful effects of high Ni content while maintaining high discharge capacity, and improves crystal stability through compositional tuning.
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 combination improves the battery's lifetime characteristics by compensating for low ion conductivity in the layered structure and maintaining high capacity retention at varying charge-discharge rates and temperatures, while ensuring safety and energy density.
Implementation Method 1
an operating potential is defined by redox of Ni2+←→Ni4+ instead of redox of Mn3+←→Mn4+
Data Source
AI summary
An active material for a secondary battery whose lifetime characteristics are improved is provided. The active material for a secondary battery includes a first active material represented by Lip[M1mM22-m-nM3n]O4, wherein M1 is at least one selected from Ni, Cr, Fe, Co, and Cu; M2 is at least one selected from Mn, Ti, and Si, and contains Mn; M3 is at least one selected from Li, B, Mg, Al, Na, and Ca; and 0≦p, 0<m, 0<n, and m+n<2; and a second active material represented by Liq[LiaXxZzMn1-a-x-z]O2, wherein X is at least one selected from Ni, Cr, Fe, Co, and Cu; Z is at least one selected from Al, Mg, B, Si, Na, Ca, and Ti; and 0≦q, 0<a, 0<x, 0≦z, and a+x+z<1.