NASICON-Type Lithium Ion Additive for Negative Electrode Efficiency
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Solution Overview
Problem
Current lithium secondary batteries face challenges in maximizing negative electrode efficiency due to the use of reversible additives that affect battery performance, necessitating the development of an irreversible lithium ion additive that provides ions during initial charging without contributing to subsequent charge/discharge.
Innovation Solution
A positive electrode for lithium secondary batteries incorporating a lithium ion conductive ceramic material with a NASICON-type structure, represented by Formula 1 (Li1+x+y1M12−x1M2x1(PO4)3, where M1 is Ti or Ge, and M2 is selected from Al, Cr, Ga, Fe, Sn, In, Lu, Y, or La, with specific molar ratios, which acts as an irreversible additive by providing lithium ions during the initial charge process without affecting subsequent charge/discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If reversible additives are used to increase negative electrode efficiency, then battery capacity increases, but battery performance deteriorates due to reversible charge/discharge at operating voltage range
Solution Approach 1:
The patent changes the chemical composition parameters of the additive by using a specific NASICON-type structure with lithium ions inserted into vacancy sites (Formula: Li1+x1+y1M12−x1M2x1(PO4)3), transforming the additive from reversible to irreversible behavior, thereby resolving the contradiction between capacity increase and performance maintenance
Solution Approach 2:
The patent creates a composite material system combining the NASICON-type lithium ion conductive ceramic with the positive electrode active material, where the ceramic provides irreversible lithium ions while the active material handles reversible charge/discharge, thus achieving both increased capacity and maintained performance
2Productivity
If lithium ion conductive ceramic material with NASICON-type structure is used as irreversible additive, then negative electrode efficiency increases, but device complexity increases
Solution Approach 1:
The NASICON-type ceramic material serves multiple functions simultaneously: it acts as a lithium ion source, provides ionic conductivity, and functions as an irreversible additive, thereby increasing negative electrode efficiency without proportionally increasing device complexity
Solution Approach 2:
The patent applies the lithium ion conductive ceramic material locally within the positive electrode mixture layer rather than throughout the entire battery system, optimizing negative electrode efficiency at the electrode level while minimizing overall device complexity
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
This solution effectively increases the efficiency of the negative electrode and enables the implementation of high-capacity lithium secondary batteries by providing additional lithium ions for the solid electrolyte interface formation and maintaining high ionic conductivity, thereby enhancing battery performance and capacity retention.
Implementation Method 1
the lithium ion additive is a lithium ion conductive ceramic material represented by Formula 1 below, and the lithium ion conductive ceramic material has a structure in which lithium ions are additionally inserted into vacancy sites of a NASICON-type (Na super ionic conductors-type) structure
Data Source
AI summary
Provided is a positive electrode for a lithium secondary battery, the positive electrode including a positive electrode mixture layer on a positive electrode current collector, wherein the positive electrode mixture layer includes a positive electrode active material and a lithium ion additive, the lithium ion additive is a lithium ion conductive ceramic material represented by Formula 1 below, and the lithium ion conductive ceramic material has a structure in which lithium ions are additionally inserted into vacancy sites of a NASICON-type (Na super ionic conductors-type) structure.Li1+x1+y1M12−x1M2x1(PO4)3 [Formula 1]In Formula 1, M1 is at least one of Ti and Ge, M2 is one or more selected from the group consisting Al, Cr, Ga, Fe, Sn, In, Lu, Y, and La, and 0<x1≤0.3, and 1.7≤y1≤2.0.