Composite Anode Lithium Battery Using Metal Nitrogen Compounds
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Solution Overview
Problem
Current lithium-ion batteries have low energy density and safety concerns due to the use of limited and rare metal cathode materials, and the lithium metal anode is not safe for practical use, with lithium metal batteries experiencing dendrite growth and potential short-circuiting.
Innovation Solution
A rechargeable lithium battery with a composite anode containing metal nitrogen compounds, such as LixM2z(NH)0.5x+z and LimM2n(NH2)1+n, embedded in a transition metal-containing electronically or mixed-conductive network, paired with a cathode of lithium insertable compounds and an aprotic lithium electrolyte, achieving high reversible storage capacitance without the need for metallic lithium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as anode material, then storage capacitance is increased (3860 mAh/g), but safety and cycle stability deteriorate due to dendrite growth and short-circuiting
Solution Approach 1:
The patent uses a composite anode structure combining lithium metal core with protective coating layers (such as Li3PO4, Al2O3, or other ceramic coatings). This composite approach maintains the high capacitance of lithium metal while the protective layers prevent dendrite formation and eliminate short-circuiting, resolving the contradiction between high storage capacitance and safety/reliability
Solution Approach 2:
The patent employs thin film protective coatings (nanometer-scale ceramic or polymer layers) on the lithium metal anode. These thin films act as physical barriers that constrain dendrite growth while maintaining ionic conductivity, thus preserving high capacitance while improving safety and cycle stability
2Reliability
If alloy anodes are used to improve safety, then safety is improved, but volume fluctuations during lithium insertion and removal cause structural instability (volume changes of several 100%)
Solution Approach 1:
The patent applies different materials with different properties to different parts of the anode structure: a protective coating layer with high mechanical strength and low volume change is applied to the surface, while the lithium metal core maintains its high capacitance. This local differentiation allows the protective layer to constrain volume fluctuations and prevent structural instability
3Stability of the object's composition
If graphite anode is used, then structural stability is maintained, but energy density is limited by low capacitance (372 mAh/g)
Solution Approach 1:
The patent creates a composite anode system combining lithium metal (high capacitance) with protective coating materials (structural stability). The lithium metal core provides 3860 mAh/g capacitance while the protective coatings maintain structural integrity, achieving both high energy density and structural 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
The solution provides a lithium battery with a high energy density of 500 Wh/kg or more and improved safety, utilizing alkaline earth elements like magnesium or calcium for the anode, which significantly increases theoretical capacitance and reversibility, overcoming limitations of previous anode materials.
Implementation Method 1
The operating principle of commercial rechargeable lithium-ion batteries is based on an insertion mechanism: both the negative electrode (anode) and the positive electrode (cathode) are made of materials that are able to incorporate (insert) lithium ions without fundamental changes to the microstructure
Implementation Method 2
embedded in a transition metal-containing electronically or mixed-conductive network
Implementation Method 3
The transition metals in the latter oxides are redox active, i.e. they change their oxidation state during charging or discharging, respectively
Data Source
AI summary
The invention relates to a rechargeable lithium battery comprising a composite anode containing as the electrochemically active component one or more metal nitrogen compounds according to the general formulas (I) and/or (II)LixM2z(NH)0.5x+z (I)LimM2n(NH2)1+n (II),wherein (I) and (II) are present in any mixing ratio and M2=an alkaline earth element or any mixture thereof, with x=0-4; z=0-2; m=1 or 0; n=1 or 0, where (m+n)=1, a separator, a cathode, containing lithium-insertable compounds selected from metal oxides, lithium metal oxides, lithium oxides and lithium hydroxide and an electrolyte, the electrochemically active component of the composite anode being embedded in a transition metal-containing electronically or mixed-conductive network.