Sulfur-Doped Composite Cathode for Lithium Battery Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium secondary batteries face challenges in achieving high rate capabilities and long lifetime characteristics, especially under high voltage conditions, due to instability in the cathode active material structure during charging and discharging.
Innovation Solution
A composite cathode active material is developed, comprising a lithium metal oxide with a layered-spinel structure doped with sulfur, specifically formulated as xLi2MnO3.(1−x−y)LiMO2.yLiMn2O4, where 0<x<0.6 and 0<y<0.1, which includes metals like Mn, V, Cr, Fe, Co, Ni, and others, and a method of manufacturing this material involving manganese sulfate, a sulfate of a metal or metalloid, and lithium carbonate, followed by heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high voltage conditions are used to increase energy density, then battery capacity is improved, but cathode active material structure stability deteriorates
Solution Approach 1:
The patent uses a composite cathode active material comprising Li2MnO3 and LiMn2O4 in a molar ratio of 9:1 to 1:1. This composite structure combines the high capacity characteristics of Li2MnO3 with the structural stability of LiMn2O4, resolving the contradiction between achieving high battery capacity and maintaining cathode material structure stability under high voltage conditions.
Solution Approach 2:
The patent introduces sulfur doping at specific positions within the cathode active material structure (0.01-5 mol% relative to total metal elements). This local modification of the crystal structure stabilizes the oxygen lattice without significantly affecting the overall capacity, thereby maintaining both high energy density and structural stability.
2Speed
If high rate capability is pursued through material composition changes, then charge/discharge speed is improved, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the molar ratio parameters of Li2MnO3 and LiMn2O4 (9:1 to 1:1) and controls sulfur content (0.01-5 mol%) to achieve high rate capability. By adjusting these compositional parameters, the material achieves improved charge/discharge rates while maintaining a relatively simple manufacturing process using conventional solid-state reaction methods.
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 composite cathode active material enhances the structural stability and electrochemical properties of lithium secondary batteries, improving their high rate capability and lifetime characteristics by stabilizing the oxygen lattice and maintaining capacity and voltage performance.
Implementation Method 1
stabilizing the oxygen lattice
Implementation Method 2
heat treating the second mixture to manufacture the composite cathode active material
Data Source
AI summary
A composite cathode active material including a lithium metal oxide including an oxide Formula 1 and sulfur,xLi2MnO3.(1−x−y)LiMO2.yLiMn2O4 (1)wherein 0<x<0.6, 0<y<0.1, and M is at least one selected from a metal and a metalloid.