Li-Rich Layered Cathode Material via Molten-Salt Ion Exchange
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Solution Overview
Problem
Lithium-ion batteries face challenges with voltage decay in Li- and Mn-rich layered oxides (LMRs) due to irreversible oxygen release and electrolyte decomposition, which affect energy density and safety, and current methods have not effectively addressed these issues.
Innovation Solution
A method involving the production of a microspherical precursor through co-precipitation, followed by calcination with sodium carbonate and lithium carbonate, and an ion exchange process under molten LiNO3/LiCl to form a lumpy residue, resulting in a cathode material with a dual phase layered structure where transition metal ions occupy interlayer sites, stabilizing the honeycomb structure and suppressing oxygen release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Li- and Mn-rich layered oxides (LMRs) are used as cathode materials to increase energy density, then energy density is improved, but voltage decay occurs due to irreversible oxygen release and electrolyte decomposition
Solution Approach 1:
The patent applies local quality by introducing a core-shell structure where the surface layer has different composition and properties from the core. The surface is modified with Li2SiO3 coating and doped with elements like Al, Mg, or Ti to create a protective layer that locally suppresses oxygen release and electrolyte decomposition, while the core maintains the high-capacity LMR composition for energy density.
Solution Approach 2:
The patent employs composite materials by combining LMR with other materials to form a composite cathode structure. This includes core-shell composites where LMR forms the core and a protective shell material (such as Li2SiO3 or doped compounds) forms the outer layer, creating a composite that simultaneously achieves high energy density and voltage stability.
2Reliability
If surface coating, doping, or defect engineering is applied to address voltage decay, then voltage stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated structure. The core-shell design combines the high-capacity LMR core with a protective shell that simultaneously provides oxygen release suppression, electrolyte decomposition prevention, and structural stability. The doping elements are incorporated during synthesis rather than requiring separate post-processing steps, reducing manufacturing complexity.
Solution Approach 2:
The patent applies preliminary action by pre-forming the core-shell structure and incorporating dopants during the synthesis process before electrode fabrication. The protective shell and doped regions are created in advance during the material synthesis stage, eliminating the need for complex post-synthesis coating or modification steps in the manufacturing process.
3Object-affected harmful factors
If irreversible oxygen release and electrolyte decomposition are suppressed, then safety is improved, but initial Coulombic efficiency decreases due to gas release during activation
Solution Approach 1:
The patent applies this principle by using a sacrificial protective layer that can undergo controlled decomposition during initial cycles to release gas, while the main bulk material remains protected. The thin surface coating or sacrificial shell serves as a disposable barrier that manages gas release during activation, protecting the underlying high-capacity material and maintaining both safety and acceptable initial efficiency.
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 approach significantly reduces voltage decay, maintaining average voltage stability for at least 50 charge-discharge cycles with minimal capacity loss, enhancing the cycling stability and safety of lithium-ion batteries.
Implementation Method 1
performing an ion exchange process to the intermediate product under molten LiNO3/LiCl to form a lumpy residue
Implementation Method 2
producing a microspherical precursor by way of co-precipitation
Data Source
AI summary
A method for preparing an electrode material includes: a) producing a microspherical precursor by way of co-precipitation; b) forming an intermediate product by calcining the precursor with a stoichiometric amount of sodium carbonate, lithium carbonate and a structural stabilizer; and c) performing an ion exchange process to the intermediate product under molten LiNO3/LiCl to form a lumpy residue. An electrode for lithium-ion battery includes an electrode material having a general formula of Li[Li1/3(TMxAly)]O2, and lithium-ion battery comprising an electrode such as a cathode having the above electrode material are also addressed.