Porous Lithium Composite Cathode Material for Stable Battery Cycling
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Solution Overview
Problem
Existing lithium secondary battery technologies require improvement in initial charge and discharge efficiency and cycle characteristics, as current methods do not fully optimize the performance of lithium composite metal compounds used as positive electrode active materials.
Innovation Solution
A lithium composite metal compound represented by the formula Li[Lix(Ni(1-y-z-w)CoyMnzMw]O2, where M represents elements like Mn, Fe, Cu, Ti, Mg, Al, W, B, Mo, Zn, Sn, Zr, Ga, and V, with specific physical properties such as pore volume, pore distribution, and content of lithium carbonate and hydroxide, is developed. This compound is manufactured through a process involving calcination, water washing, and drying under controlled conditions to enhance its performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fine pores are formed in positive electrode active materials to improve battery performance, then charge and discharge efficiency is improved, but initial charge and discharge efficiency and cycle characteristics deteriorate
Solution Approach 1:
The invention changes the physical and chemical parameters of the positive electrode active material by controlling pore size distribution (15-200 nm), total pore volume (0.02-0.08 mL/g), and surface area (0.5-2.0 m²/g). These parameter optimizations resolve the contradiction by creating a pore structure that enhances charge/discharge efficiency while maintaining cycle stability through controlled pore architecture rather than excessive fine pores
Solution Approach 2:
The invention uses composite lithium composite metal oxides with specific compositions (Li[Lix(Ni(1-y-z-w)CoyMnzMw)1-x]O2) that combine multiple metal elements. This composite material approach allows simultaneous optimization of electrochemical performance and structural stability, resolving the contradiction between improved efficiency and maintained reliability
2Reliability
If lithium carbonate and lithium hydroxide contents are reduced to improve cycle characteristics, then manufacturing precision and process control complexity increase
Solution Approach 1:
The invention performs preliminary washing and drying actions before final product formation. The washing step removes lithium carbonate and lithium hydroxide, and the drying step prevents their reformation. This preliminary action approach achieves low impurity content (Li2CO3: 0.01-0.3 mass%, LiOH: 0.01-0.2 mass%) while managing process complexity through structured sequential operations
3Reliability
If washing steps are added to remove lithium carbonate and lithium hydroxide, then cycle characteristics are improved, but manufacturing process complexity increases
Solution Approach 1:
The invention utilizes the porous structure of the positive electrode active material during washing, allowing efficient removal of lithium carbonate and lithium hydroxide through the pore network. This approach achieves effective impurity removal with simplified washing procedures, improving cycle characteristics while controlling process complexity through the material's inherent porous architecture
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 developed lithium composite metal compound exhibits improved initial charge and discharge efficiency and cycle characteristics, leading to higher discharge capacity retention ratios and better thermal stability, thus enhancing the overall performance of lithium secondary batteries.
Implementation Method 1
measurement of nitrogen adsorption and desorption isotherms at a liquid nitrogen temperature
Implementation Method 2
a step of calcining a mixture of a lithium compound and a transition metal compound
Implementation Method 3
a water washing step of removing the lithium compound remaining in the lithium composite metal compound by water washing
Implementation Method 4
a step of drying the water-washed lithium composite metal compound
Data Source
AI summary
Provided are a lithium composite metal compound having excellent cycle characteristics in the case of being used as battery materials, a positive electrode active material for a lithium secondary battery using the same, a positive electrode using the same, and a lithium secondary battery using the same. The lithium composite metal compound is represented by Composition Formula (I), in which physical property values of pores that are obtained from measurement of nitrogen adsorption and desorption isotherms at a liquid nitrogen temperature satisfy requirements (1) and (2).