Olivine Silicate Cathode Structure Retention
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Solution Overview
Problem
Lithium-ion battery cathodes made from Li2MnSiO4 silicate materials abruptly amorphize during charging, leading to gradual performance loss over charge/discharge cycles, necessitating a crystalline silicate material that retains its structure for improved battery reliability.
Innovation Solution
A silicate material with an olivine crystallographic structure, specifically of formula AaZzMnSiO4, where A is an alkali metal, Z is beryllium, magnesium, or calcium, and M is iron, nickel, or manganese, with stoichiometric coefficients that satisfy certain conditions, is synthesized using a process involving a liquid bath of fused alkali metal and solid olivine crystallographic structure materials, or through electrochemical reduction of an olivine material to maintain the crystal structure during battery cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Li2MnSiO4 silicate material is used as battery cathode, then high theoretical specific capacity (325-333 mAh/g) is achieved, but the material abruptly amorphizes during charging causing gradual performance loss
Solution Approach 1:
The patent modifies the chemical composition parameters of the silicate material by introducing multiple cations (Li, Na, K, Mg, Ca, Mn, Fe, Co, Ni) with controlled stoichiometric ratios. This compositional parameter change stabilizes the crystal structure during electrochemical cycling, preventing amorphization while maintaining high capacity
Solution Approach 2:
The patent creates a composite cathode material combining multiple alkali metals (Li, Na, K) and transition metals (Mn, Fe, Co, Ni) within a silicate framework. This composite structure leverages the beneficial properties of each element to achieve both high capacity and structural stability during charge/discharge cycles
2Reliability
If polyanionic materials are used for battery electrodes, then battery safety is improved by limiting oxygen release, but limited crystallographic structures are available compared to oxides and spinels
Solution Approach 1:
The patent develops a universal silicate structure framework that can accommodate multiple different cations (alkali metals and transition metals) in various combinations. This multi-functional approach allows the same base structure to provide both safety benefits from polyanionic character and structural diversity through cation substitution
3Use of energy by moving object
If Li2MnSiO4 is used as cathode material, then lithium insertion potentials are optimized for Mn2+, but the material loses its crystallographic structure during charging/discharging cycles
Solution Approach 1:
The patent applies local quality by creating distinct structural zones within the cathode material where different cations occupy specific crystallographic sites. The Li, Na, and K atoms occupy different positions in the olivine structure, with each site optimized for its specific ionic radius and charge, thereby maintaining local structural stability during lithium insertion/extraction
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 olivine structured silicate material effectively retains its crystal structure during battery charging and discharging, maintaining high specific capacity and operational reliability over multiple cycles, enhancing the performance and safety of lithium-ion batteries.
Implementation Method 1
maintaining a liquid bath comprising, preferably constituted by, the first material in fusion and the second material in the solid state
Implementation Method 2
electrochemically reducing said material of formula (II) in the presence of an element A source electrode under conditions favorable to the formation of the material of formula (I)
Data Source
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AI summary
The present invention relates to a method for manufacturing a material with olivine crystallographic structure of formula (I) AaZzMmSiO4 in which A is chosen from Li, Na, K, and mixtures thereof, Z is chosen from Be, Mg, Ca, Sr, Ba and mixtures thereof, M is chosen from Fe, Ni, Co, Mn, Cr and mixtures thereof, a, z and m are the stoichiometric coefficients of A, Z and M respectively, and which satisfy the following conditions: z > 0, m > 0, a > 0, a + z + m ≤ 2, and 2 ≤ (4 - a - 2z) /m < 4, said method comprising at least the steps consisting of i. to have a material of olivine crystallographic structure and of formula (II) ZzMmSiO4, obtained by oxidation of a material of olivine crystallographic structure of formula (III) Zz'MmSiO4, in which Z, M, z and m are such as defined above and the stoichiometric index z' is such that z' > z, and ii.electrochemically reduce said material of formula (II) in the presence of a source electrode of element A under conditions favorable to the formation of the material of formula (I).