Cobalt-Free Lithium Battery Additive for SEI-Stable Cycle Life
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Solution Overview
Problem
Rechargeable lithium batteries using cobalt-free positive electrode active materials face increased resistance and reduced cycle-life, especially at room temperature and high temperatures, due to structural instability and potential elution of nickel or manganese, leading to lithium dendrite formation and short circuits.
Innovation Solution
Incorporating an aliphatic cyclic acid anhydride-based compound as an electrolyte additive, which forms a stable solid electrolyte interface film on the negative electrode, reducing resistance and enhancing cycle-life characteristics even with cobalt-free positive electrode active materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cobalt-free positive electrode active material is used, then cost is reduced and safety is improved, but resistance increases and cycle-life decreases
Solution Approach 1:
A coating layer comprising a compound with formula Li2MO3 (where M is at least one element selected from Al, Si, P, S, Cl, or F) is formed on the surface of the cobalt-free positive electrode active material. This coating layer acts as an intermediary between the active material and the electrolyte, preventing direct harmful interactions while facilitating stable lithium ion transport, thereby reducing resistance increase and improving cycle-life.
Solution Approach 2:
The patent modifies the surface composition and structure of the positive electrode active material by introducing a coating layer with specific chemical formula Li2MO3. This parameter change in surface composition stabilizes the material structure during cycling, reduces nickel or manganese elution, and maintains low resistance, thus improving cycle-life without sacrificing the benefits of cobalt-free composition.
2Ease of manufacture
If cobalt-free positive electrode active material is used, then manufacturing cost is reduced, but structural instability increases leading to nickel or manganese elution
Solution Approach 1:
The patent creates a composite structure by coating the cobalt-free positive electrode active material (such as LiNi0.8Co0.1Mn0.1O2) with a layer of Li2MO3 compound. This composite structure combines the high capacity benefits of cobalt-free materials with the structural stability of the coating layer, preventing nickel or manganese elution while maintaining cost-effectiveness.
Solution Approach 2:
The surface composition parameter of the positive electrode active material is changed by introducing a coating layer with formula Li2MO3. This parameter modification enhances structural stability during charge-discharge cycles, preventing cation mixing and metal elution, while the thin coating maintains manufacturing cost-effectiveness.
3Object-affected harmful factors
If cobalt-free positive electrode active material is used, then safety is improved by reducing cobalt content, but lithium dendrite formation increases
Solution Approach 1:
The Li2MO3 coating layer serves as an intermediary interface between the cobalt-free positive electrode active material and the electrolyte. This intermediate layer promotes uniform lithium ion flux distribution during charging, preventing localized concentration gradients that lead to lithium dendrite formation, while maintaining the safety benefits of reduced cobalt content.
Solution Approach 2:
The surface chemistry parameters of the positive electrode are modified by the Li2MO3 coating layer, which alters the interfacial properties between electrode and electrolyte. This parameter change in surface composition and structure suppresses lithium dendrite formation by ensuring uniform lithium ion extraction and insertion, enhancing safety without requiring cobalt.
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 use of the aliphatic cyclic acid anhydride-based compound in the electrolyte suppresses resistance increases and improves cycle-life at both room and high temperatures, maintaining battery performance and preventing short circuits.
Implementation Method 1
Incorporating an aliphatic cyclic acid anhydride-based compound as an electrolyte additive, which forms a stable solid electrolyte interface film on the negative electrode
Data Source
AI summary
A rechargeable lithium battery including a positive electrode including a cobalt-free positive electrode active material with a layered structure, a negative electrode, and an electrolyte is provided.