Multi-Cationic Li-Boracite Electrolyte for Stable Ionic Conduction
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Solution Overview
Problem
Current lithium boracite compositions face challenges in achieving thermodynamically stable phases with high ionic conductivity and environmental stability, particularly due to the difficulty in replacing the B—O framework with other cationic frameworks.
Innovation Solution
The development of new Li-boracite compositions involves introducing multi-dopant species into the B3+ site, leading to the formation of thermodynamically stable phases. This is achieved by partially or fully replacing the tetrahedral BO4 units in the parent lithium chloroboracite, Li4B7O12Cl, with a combination of trivalent, bivalent, tetravalent, or pentavalent species, resulting in compounds like Li4−xB7−yMyO12−zClw.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the B—O framework is replaced with other cationic frameworks, then compositional variety is increased, but the replacement is highly difficult or often impossible due to the very small ionic radius of the B3+ sites
Solution Approach 1:
The patent applies local quality by introducing multiple dopant species (Al, Fe, La, Y, Mo, Be, Si, Cr, As, Mn, V, Co, Ge, Ti, P) at specific B3+ sites within the boracite structure. Each dopant is strategically placed to optimize local chemical environment and ionic radius matching, enabling compositional variety while maintaining structural integrity despite the small ionic radius constraint
Solution Approach 2:
The patent creates composite materials by combining multiple dopant species within the boracite framework. The multi-dopant composition (Li4-xB7-yMyO12-zClw) integrates different cations with varying ionic radii and chemical properties, achieving both compositional diversity and structural stability through synergistic interactions among the dopants
2Stability of the object's composition
If multi-dopant species are introduced into the B3+ site, then thermodynamic stabilization is enhanced through increased configurational entropy, but the structural complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the dopant composition (x, y, z parameters in Li4-xB7-yMyO12-zClw) to optimize configurational entropy. By adjusting the concentrations of different dopant species and controlling vacancy generation, the patent achieves thermodynamic stabilization while managing structural complexity through compositional tuning
Solution Approach 2:
The patent utilizes phase transitions by forming stable crystalline phases from glass-ceramic precursors. The multi-dopant boracite compositions undergo controlled phase transitions during sintering, transforming from amorphous glass-ceramic matrices to ordered crystalline structures with enhanced thermodynamic stability and optimized ionic conductivity
3Reliability
If Al doping is performed to form glass-ceramic stable against Li metal, then electrochemical stability is improved, but the cost increases due to limited dopant options
Solution Approach 1:
The patent applies universality by designing a multi-functional dopant system where various cations (Al, Fe, La, Y, Mo, etc.) can serve multiple purposes: stabilizing the boracite phase, enhancing ionic conductivity, improving electrochemical stability against Li metal, and adjusting cost. This universal dopant approach replaces the single-dopant limitation with a flexible multi-component system
Solution Approach 2:
The patent incorporates cost-effective dopants such as Fe, Mn, Co, and Ni alongside more expensive rare-earth elements like La and Y. By combining cheap and expensive dopants in optimized ratios, the patent reduces overall material cost while maintaining electrochemical stability and performance, making the technology more economically viable
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 concurrent multi-specie doping of the B3+ site and vacancy generation increase configurational entropy, enhancing the thermodynamic stabilization of non-obvious species on the B3+ site, thereby improving the stability, ionic conductivity, and cost-effectiveness of the Li-boracite compositions.
Implementation Method 1
The concurrent multi-specie doping of the B3+ site and vacancy generation of either Li, O or Cl increases the configurational entropy (i.e. 100 meV/atom) which subsequently increases the thermodynamic stabilization of non-obvious species on the B3+ site
Implementation Method 2
Low-cost multi-cationic li-boracite as a solid state ionic conductor for lithium batteries
Data Source
AI summary
A compound has the formula Li4−xB7−yMyO12−zClw, wherein Li, O, and Cl vacancies are allowed and M is either a one-way, two-way or three-way combination of the following species: Al3+, Fe3+, B3+, La3+, Y3+, Mo3+, Be2+, Si4+, Cr4+, As3+, Mn2+, V2+, Co2+, Ge2+, Fe2+, Mo4+, Mo6+, As3−, Ti2+, P5+, As0+, and wherein 0≤x<2, 0<y<6, 0≤z<1, and 0<w<2 either satisfy a charge balance mechanism with their respective defect site B3+, Li+, O2−, or Cl−, or satisfy any combination that maintains charge neutrality of the compound, and wherein when M comprises Al3+, M is a two-way or three-way combination. A glass ceramic composition includes the compound. A lithium ion battery includes a solid state ionic conductor, wherein the solid state ionic conductor includes the compound.