Lithium Cobalt Additive Composite for Battery Capacity Loss
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Solution Overview
Problem
Lithium secondary batteries face challenges in increasing capacity due to high irreversible capacity loss in anode materials, despite using high-energy-density non-carbon anode materials, and existing irreversible additives do not sufficiently improve cathode capacity characteristics.
Innovation Solution
A cathode additive composite represented by the formula (1-y-z)(Li6Co1-xMxO4)-y(LiCo1-xMxO2)-z(Li2O) is developed, where M includes elements like P, B, F, Ni, W, Ti, Zr, Mg, and Al, with specific molar ratios, which is formed through calcination of cobalt and lithium precursors under an inert atmosphere, enhancing both thermal and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-carbon anode material (silicon, tin, oxides) is used to increase capacity, then energy density is improved, but initial efficiency is low causing large lithium consumption and irreversible capacity loss
Solution Approach 1:
The patent introduces an irreversible additive as an intermediary substance in the cathode that preferentially reacts with lithium during initial cycles. This additive acts as a mediator that consumes excess lithium that would otherwise be lost, thereby reducing the irreversible capacity loss while allowing the high-capacity non-carbon anode material to function effectively.
Solution Approach 2:
The patent modifies the cathode composition by adding specific substances (irreversible additives) that change the electrochemical parameters of the system. By adjusting the amount and type of irreversible additive, the initial efficiency and irreversible capacity loss are optimized while maintaining the high energy density benefits of non-carbon anode materials.
2Loss of energy
If irreversible additive is added to cathode to reduce capacity loss, then lithium consumption is reduced, but capacity characteristics of cathode become insufficient
Solution Approach 1:
The patent employs composite cathode materials that combine the irreversible additive with other cathode active materials. This composite structure allows the irreversible additive to perform its function of reducing lithium consumption while the other components maintain or enhance the capacity characteristics, thereby resolving the trade-off between reducing irreversible loss and maintaining capacity.
Solution Approach 2:
The irreversible additive is designed to serve multiple functions: it reduces irreversible capacity loss, maintains capacity characteristics, and potentially improves cycle life. By making the additive multi-functional, the patent avoids the need to sacrifice capacity characteristics while achieving reduced lithium consumption.
3Loss of energy
If graphite anode is used, then initial efficiency is high, but capacity per unit mass is limited to 372 mAh/g
Solution Approach 1:
The irreversible additive serves as an intermediary that compensates for the low capacity of graphite by managing lithium consumption. This allows the system to either use graphite with improved efficiency or transition to higher-capacity non-carbon materials without suffering from excessive irreversible losses.
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 cathode additive effectively reduces initial irreversible capacity, improves capacity characteristics, and acts as both an irreversible additive and cathode active material, enhancing the overall performance and energy density of lithium secondary batteries.
Implementation Method 1
a material which can provide a lithium ion source or a storage material to the cathode material and which exhibits electrochemical activity after the first cycle
Implementation Method 2
formed through calcination of cobalt and lithium precursors under an inert atmosphere
Data Source
AI summary
Disclosed are a cathode additive of a lithium secondary battery and a method of preparing the same. The lithium secondary may have high irreversible capacity and further improved capacity characteristics.