Mo-Doped Ternary Cathode for Li-Ion Battery Capacity and Stability
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Solution Overview
Problem
Lithium ion batteries using LiCoO2 cathode active materials face challenges with high cost, thermal instability, and limited specific capacity, while ternary materials like LiNi0.8Co0.1Mn0.1O2 have relatively low specific capacity and capacity retention issues.
Innovation Solution
The development of a cathode active material with the chemical formula Li[(Ni0.8Co0.1Mn0.1)1-xMox]O2, where 0<x≦0.05, is achieved through a method involving the mixing of Li, Ni, Co, Mn, and Mo sources in a multi-carboxylic acid solution, forming a sol, then spray drying and heating to produce a dry gel, which is further processed to enhance thermal stability and specific capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LiCoO2 is used as cathode active material, then high capacity and high voltage are achieved, but cost increases due to scarce cobalt
Solution Approach 1:
The patent changes the compositional parameters by replacing cobalt with nickel, manganese, and molybdenum in controlled ratios (LiNi0.8Co0.1Mn0.1O2 and LiNi0.7Co0.2Mn0.1O2), thereby reducing cobalt content while maintaining electrochemical performance and lowering material cost
Solution Approach 2:
The patent creates composite ternary cathode materials by combining multiple metal elements (Ni, Co, Mn, Mo) in specific proportions, achieving a balance between capacity, stability, and cost-effectiveness through synergistic interactions among the components
2Power
If LiCoO2 is used as cathode active material, then high voltage is achieved, but thermal stability deteriorates due to decomposition by heat
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating thermally stable elements (Mn, Mo) alongside Ni and Co in optimized ratios, which suppresses exothermic decomposition reactions while preserving high voltage characteristics
Solution Approach 2:
The patent converts the potentially harmful thermal decomposition behavior into beneficial thermal stability by using Mn and Mo doping to suppress oxygen release and exothermic reactions, thereby improving safety without sacrificing voltage performance
3Quantity of substance
If LiNi0.8Co0.1Mn0.1O2 is used to improve specific capacity, then cost and thermal stability are improved, but capacity retention deteriorates after numerous cycles
Solution Approach 1:
The patent optimizes the compositional parameters by adjusting the ratios of Ni, Co, Mn, and Mo (comparing LiNi0.8Co0.1Mn0.1O2 with LiNi0.7Co0.2Mn0.1O2), where increased Mo content and adjusted Ni:Co ratio enhance structural stability and reduce capacity fade during cycling
Solution Approach 2:
The patent introduces Mo as an intermediary element that mediates between Ni (providing capacity) and Co/Mn (providing stability), with Mo doping suppressing cation mixing and Jahn-Teller distortion to improve long-term cycling stability
4Quantity of substance
If content of Ni is increased to improve specific capacity, then capacity is improved, but thermal stability may deteriorate
Solution Approach 1:
The patent precisely controls the compositional parameters by limiting Ni content to 0.7-0.8 while maintaining Co and Mn at 0.1-0.2 each, and introducing Mo doping, thereby achieving high capacity without excessive thermal instability
Solution Approach 2:
The patent creates a balanced composite material system where high-Ni content is compensated by stabilizing elements (Co, Mn, Mo), achieving synergistic effects that provide both high capacity and acceptable thermal stability
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 approach results in improved thermal stability and specific capacity retention, with Mo doping reducing crystalline grain size and enhancing lithium ion diffusion, leading to better electrochemical performance and capacity retention in lithium ion batteries.
Implementation Method 1
heating the sol at a temperature in a range from 50° C. to 80° C. to form a wet gel
Implementation Method 2
spray drying the wet gel to form a dry gel
Implementation Method 3
heating the dry gel at a first temperature and then at a second temperature, the first temperature is in a range from 400° C. to 500° C., the second temperature is in a range from 750° C. to 850° C.
Data Source
AI summary
A method for making a cathode active material of a lithium ion battery, the cathode active material being represented by a chemical formula of Li[(Ni0.8Co0.1Mn0.1)1-xMox]O2, wherein 0<x≦0.05. Source liquid solutions of Li, Ni2+, Co2+, Mn2+, and Mo6+ are mixed in stoichiometric ratio in a multi-carboxylic acid solution to form a solution. The solution is heated at 50° C. to 80° C. to form a wet gel. The wet gel is spray dried to form a dry gel. The dry gel is heated at a first temperature and then at a second temperature, the first temperature is in a range of 400° C. to 500° C., the second temperature is in a range of 750° C. to 850° C.