Lithium Cobalt Positive Active Material pH Control
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Solution Overview
Problem
Lithium rechargeable batteries face challenges in achieving high capacity, cycle-life, and stability due to limitations in positive active materials, particularly with existing lithium cobalt-based compounds that may have unsatisfactory pH ranges and residual Li2CO3 or LiOH, leading to side reactions and deteriorated battery characteristics.
Innovation Solution
A lithium cobalt-based compound with a pH range of 7 to 10, represented by Chemical Formula LiaCo1-xMxO2, where 0.95≤a≤1.03 and M is Ni, Mn, B, Mg, Ca, Sr, Ba, Ti, V, Cr, Fe, Cu, Al, or a combination thereof, is developed, along with a method involving mixing cobalt and lithium raw materials, heat-treating at 1000° C to 1100° C, and using spherical Co3O4 particles to enhance particle distribution and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium cobalt-based compounds are used as positive active materials, then the battery can achieve basic operation, but the pH range is unsatisfactory and residual Li2CO3 or LiOH causes side reactions leading to deteriorated battery characteristics
Solution Approach 1:
The patent applies preliminary action by performing thorough heat treatment at 1000-1100°C before battery assembly to completely remove residual Li2CO3 and LiOH from the positive active material. This pre-removal of harmful substances prevents subsequent side reactions during battery operation, thereby improving battery characteristics and reliability.
Solution Approach 2:
The patent applies parameter changes by optimizing the heat treatment temperature range (1000-1100°C) and time conditions to achieve complete decomposition of Li2CO3 and LiOH while maintaining the structural integrity of the lithium cobalt-based compound. This precise parameter control eliminates harmful residues without degrading the active material performance.
2Reliability
If heat treatment is performed at high temperature to remove residual Li2CO3 or LiOH, then side reactions are suppressed, but energy consumption and processing time increase
Solution Approach 1:
The patent optimizes the heat treatment parameters by establishing a specific temperature range (1000-1100°C) and time duration that achieves complete removal of Li2CO3 and LiOH residues. This optimized parameter set eliminates the need for excessive energy input while ensuring thorough decomposition of harmful substances, thus resolving the contradiction between reliability improvement and energy consumption.
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 solution provides excellent initial charge and discharge efficiency, cycle-life characteristics, and stability by suppressing side reactions from residual Li2CO3 or LiOH, resulting in improved battery performance with enhanced capacity and durability.
Implementation Method 1
heat-treating the mixture
Data Source
AI summary
Disclosed are a positive active material for a rechargeable lithium battery, a method of preparing same and rechargeable lithium battery including the same, wherein the positive active material includes lithium cobalt-based compound having pH of greater than about 7 and less than about 10.