Non-Carbonaceous Nanoparticle Negative Electrode for Lithium Batteries
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Solution Overview
Problem
Lithium secondary batteries face challenges with non-carbonaceous negative active materials due to volumetric expansion and contraction during charging and discharging, leading to low capacity retention, efficiency, and reduced lifetime.
Innovation Solution
A negative active material comprising non-carbonaceous nanoparticles and crystalline carbonaceous nano-sheets with amorphous carbonaceous coating layers, which enhance lithium ion conductivity and mitigate volume changes, improving the battery's efficiency and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-carbonaceous materials are used as negative active materials, then capacity density is improved (at least ten times that of graphite), but volumetric expansion and contraction occur during charging and discharging, leading to low capacity retention ratio, low charge/discharge efficiency, and decreased lifetime
Solution Approach 1:
The patent applies the nesting principle by placing non-carbonaceous nanoparticles (high capacity density) inside a carbonaceous matrix structure. The non-carbonaceous material is embedded within the carbonaceous framework, allowing the inner material to provide high capacity while the outer carbonaceous structure provides structural stability and accommodates volume changes, thus resolving the contradiction between high capacity density and capacity retention.
Solution Approach 2:
The patent uses composite materials by combining non-carbonaceous materials (such as silicon, tin, or germanium nanoparticles) with carbonaceous materials (such as graphite, amorphous carbon, or carbon nanotubes). This composite structure allows the non-carbonaceous component to contribute high capacity density while the carbonaceous component provides structural integrity and buffers volumetric expansion, thereby maintaining both high capacity and good capacity retention.
2Quantity of substance
If non-carbonaceous materials are used as negative active materials, then capacity density is improved, but volumetric expansion and contraction occur, leading to low charge/discharge efficiency
Solution Approach 1:
The nested structure allows lithium ions to access the high-capacity non-carbonaceous nanoparticles through the carbonaceous matrix, maintaining efficient ion transport pathways while enabling the use of high-capacity materials. This resolves the contradiction by preserving charge/discharge efficiency despite using non-carbonaceous materials with higher capacity density.
Solution Approach 2:
The composite structure combines the high capacity of non-carbonaceous materials with the good ionic conductivity and structural stability of carbonaceous materials. This combination maintains efficient lithium ion transport while utilizing the high capacity of the non-carbonaceous component, thus achieving both high capacity density and good charge/discharge efficiency.
3Quantity of substance
If non-carbonaceous materials are used as negative active materials, then capacity density is improved, but volumetric expansion and contraction occur, leading to decreased lifetime
Solution Approach 1:
The nested structure protects the non-carbonaceous nanoparticles from direct contact with the electrolyte and mechanical degradation by enclosing them within the carbonaceous matrix. This protective structure prevents particle aggregation and structural collapse during cycling, thereby extending battery lifetime while maintaining high capacity density.
Solution Approach 2:
The composite material structure combines the high capacity of non-carbonaceous materials with the structural stability and protective properties of carbonaceous materials. This composite design prevents degradation mechanisms such as particle pulverization and electrolyte decomposition, thereby significantly extending the battery lifetime while utilizing high-capacity non-carbonaceous materials.
4Reliability
If amorphous carbonaceous coating layer is added on non-carbonaceous nanoparticle surface, then lithium ion conductivity is enhanced and volume changes are mitigated, but device complexity increases
Solution Approach 1:
The amorphous carbonaceous coating is applied locally on the surface of non-carbonaceous nanoparticles, providing lithium ion conductivity enhancement and volume change mitigation exactly where needed at the particle surface. This localized treatment achieves the desired functional improvement without requiring complex bulk modifications, thus balancing performance enhancement with structural simplicity.
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 negative active material structure results in improved lithium battery efficiency and extended cycle lifetime by enhancing electrical and ionic conductivity while reducing volumetric expansion, thus maintaining high capacity retention.
Implementation Method 1
a positive electrode and a negative electrode that include an active material that allows intercalation and deintercalation of lithium ions
Implementation Method 2
enhancing lithium ion conductivity
Implementation Method 3
due to volumetric expansion and contraction of a non-carbonaceous material during charging and discharging of a lithium battery
Implementation Method 4
Such lithium secondary batteries generate electric energy according to an oxidation/reduction reaction occurring when lithium ions are intercalated/deintercalated in the positive and negative electrodes
Data Source
AI summary
A negative active material and a lithium battery including the negative active material. The negative active material includes a non-carbonaceous nanoparticle capable of doping or undoping lithium; and a crystalline carbonaceous nano-sheet, wherein at least one of the non-carbonaceous nanoparticle and the crystalline carbonaceous nano-sheet includes a first amorphous carbonaceous coating layer on its surface, and thus an electrical conductivity thereof is improved. In addition, a lithium battery including the negative active material has an improved efficiency and lifetime.