Lithium Nitride Additive Coating for Stable Li-Ion Supplementation
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Solution Overview
Problem
Existing lithium-supplementing additives for lithium-ion batteries suffer from poor stability due to the instability of non-metallic lithium compounds, which limits their large-scale application.
Innovation Solution
A lithium-supplementing additive comprising pure α-phase lithium nitride, pure β-phase lithium nitride, or a mixed-phase lithium nitride, prepared by calcining metallic lithium in a nitrogen atmosphere and grinding it to obtain lithium nitride, which is then coated with a two-dimensional conductive material to enhance stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional non-metallic lithium compounds are used as lithium-supplementing additives, then lithium supplementation can be achieved, but the additives have poor stability and are easily deteriorated by reacting with water vapor and oxygen in the air
Solution Approach 1:
The patent uses lithium nitride prepared in a nitrogen atmosphere as the lithium-supplementing additive. Lithium nitride is stable in inert environments and does not readily react with water vapor and oxygen in air, thus resolving the stability issue of conventional non-metallic lithium compounds while maintaining lithium supplementation functionality
Solution Approach 2:
The patent employs a composite structure consisting of lithium nitride core particles coated with a protective shell layer. This composite material design provides both lithium supplementation capability and enhanced stability against environmental degradation, solving the contradiction between reactivity and stability
2Reliability
If lithium nitride with high lithium-ion conductivity is used, then lithium ion release is improved, but the material may react with common battery components like NMP and PVDF
Solution Approach 1:
The patent introduces a protective shell layer as an intermediary between the lithium nitride core and the battery components (NMP, PVDF). This shell acts as a barrier that prevents direct contact and harmful reactions while allowing lithium-ion transport, thus maintaining high conductivity without compromising chemical stability
Solution Approach 2:
The patent uses a thin film shell coating on lithium nitride particles. This flexible protective layer is sufficiently thin to allow lithium-ion diffusion while providing chemical protection against NMP and PVDF, resolving the contradiction between reactivity and conductivity
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 proposed lithium-supplementing additive improves the first charging efficiency and overall electrochemical performance of lithium-ion batteries by maintaining abundant lithium ions and ensuring a smooth voltage change during charging, while also offering good material stability and low production costs.
Implementation Method 1
placing the metallic lithium in a nitrogen atmosphere for calcination treatment, and grinding to obtain lithium nitride
Data Source
AI summary
Provided is a lithium-supplementing additive comprising α-phase lithium nitride and/or β-phase lithium nitride. According to the lithium-supplementing additive provided by the present application, the comprised pure α-phase lithium nitride has high lithium ion conductivity, thereby facilitating the de-intercalation of lithium ions; the comprised pure β-phase lithium nitride has a high energy barrier for lithium-ion mobility and a high decomposition voltage, so that the mobility of lithium ions in a battery system is more stable; and the comprised mixed-phase lithium nitride has reduced activity and can be prevented from reacting with widely used N-methylpyrrolidone (NMP) and polyvinylidene fluoride (PVDF) during a homogenizing process, and thus has good stability.