Olivine Phosphate Silicate Cathode for Stable Li-Ion Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium-ion batteries face issues with the amorphization of Li2MnSiO4 silicate materials during charging, leading to gradual performance loss and instability during charge/discharge cycles, and there is a lack of reported manufacturing methods for materials with olivine structure like LiFeSiO4 and LiMnSiO4.
Innovation Solution
A crystalline material with an olivine crystallographic structure of formula AzMm(SiO4)1-x(PO4)x, where A is lithium, sodium, or potassium, M is iron, nickel, or manganese, and x is a stoichiometric coefficient between 0 and 0.8, which promotes stable electrochemical performance and retains its structure during battery cycles, enhancing specific capacity by up to 35% compared to similar olivine materials without the PO4 group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li2MnSiO4 silicate material is used as lithium-ion battery cathode, then high theoretical specific capacity (325-333 mAh/g) is achieved, but the material abruptly amorphizes from the first charge resulting in gradual performance loss during charge/discharge cycles
Solution Approach 1:
The patent applies composite materials by combining silicate (SiO4) and phosphate (PO4) groups in a single crystalline structure with formula Li2-a-bMSiO4-x(PO4)x. This composite approach creates a hybrid polyanionic material that leverages the high capacity potential of silicates while incorporating the structural stability of phosphates, thereby preventing amorphization during battery cycling while maintaining high specific capacity.
Solution Approach 2:
The patent employs parameter changes by systematically varying the stoichiometric coefficients (a, b, x) in the formula Li2-a-bMSiO4-x(PO4)x to optimize both capacity and stability. By adjusting the ratio of silicate to phosphate groups and the valence state of the transition metal M, the material achieves a balance between high electron transfer capacity and structural integrity during charge/discharge cycles.
2Reliability
If LiFeSiO4 and LiMnSiO4 materials with olivine structure are manufactured, then stable electrochemical performance is achieved, but no manufacturing method has been reported in scientific and technical literature
Solution Approach 1:
The patent applies preliminary action by using sol-gel synthesis to pre-form a homogeneous amorphous precursor containing all necessary elements (Li, M, Si, P, O) in the correct stoichiometric ratios before controlled crystallization. This preliminary homogeneous mixing at the molecular level ensures that the subsequent heat treatment produces the desired olivine-phase hybrid material with consistent composition and structure, overcoming the lack of reported manufacturing methods.
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 material exhibits improved electrochemical properties with increased specific capacity and stability during charge/discharge cycles, maintaining the olivine structure and enhancing ionic conductivity through increased mobility of ions within the olivine structure, leading to better battery performance.
Implementation Method 1
preparation of a sol by mixing together a first solution of a silicate and a second solution of a constituent comprising at least one chemical element chosen from iron, nickel and manganese
Implementation Method 2
The gel thus obtained is then pyrolysed so as to form a crystalline material
Implementation Method 3
The gel thus obtained is then pyrolysed so as to form a crystalline material with an olivine crystallographic structure
Implementation Method 4
The olivine crystallographic structure of the material of formula (I) promotes the insertion and extraction of element A
Data Source
Figure 1a~5
Figure 2~3
Figure 4
AI summary
Material of olivine crystallographic structure and formula (I) AaZzMm (SiO4)1-x(PO4)x in which: - A is selected from lithium, sodium, potassium and mixtures thereof, - Z is selected from beryllium, magnesium, calcium, strontium, barium and mixtures thereof, - M is selected from iron, nickel, cobalt, manganese, chromium and mixtures thereof, the oxidation state of element M being greater than or equal to 2 and less than 4, - a, z, m and x are the stoichiometric coefficients of the chemical elements A, Z, M and of the PO43− group respectively, and satisfy the following conditions: o 0 <a<1−x2, o 0<x<0,8, o 0< m, o 0<a<1−x2, et o a+z≤1−x2.