Li-Excess Metal Oxide Cathode for High-Energy Battery
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Solution Overview
Problem
Existing methods for enhancing the energy density of secondary batteries, such as pre-adding lithium to negative electrodes or using Li-rich compounds in positive electrodes, face challenges like complex manufacturing processes, high costs, and difficulties in controlling doping amounts, leading to issues with mass production and electrode stability.
Innovation Solution
A nonaqueous electrolytic solution secondary battery design featuring a negative electrode with an initial charge/discharge efficiency of 75% or less, using a negative electrode active material charged with a positive electrode containing a metal oxide (AxMeOy) where A is Na or K, Me is Ni or Cu, and x and y range from 1.9 to 2.1, which reduces irreversible lithium reactions and improves energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pre-adding lithium to negative electrode or using Li-rich compounds in positive electrode to compensate irreversible capacity, then energy density is improved, but manufacturing complexity increases and mass production becomes difficult
Solution Approach 1:
The patent pre-calculates the irreversible capacity loss of the negative electrode and determines the exact amount of lithium to be added to the positive electrode before assembly. This preliminary calculation and preparation eliminates the need for complex post-assembly lithium addition processes, simplifying manufacturing while achieving the desired energy density compensation.
Solution Approach 2:
The patent uses the positive electrode as an intermediary reservoir to store the compensation lithium. Instead of directly modifying the negative electrode or using complex external lithium sources, the lithium is incorporated into the positive electrode structure, which then serves as a controlled release mechanism during battery operation, simplifying the overall system.
2Reliability
If pre-adding lithium to negative electrode to compensate irreversible capacity, then initial charge/discharge efficiency is improved, but control of doping amount becomes difficult
Solution Approach 1:
The patent replaces the mechanical/diffusion-based lithium doping process (which is difficult to control) with a stoichiometric compound formation approach. By using Li-rich compounds with defined chemical formulas (such as Li2NiO3, Li2CuO3), the lithium content is precisely determined by chemical composition rather than by diffusion processes, enabling accurate control of lithium amount.
Solution Approach 2:
The patent changes the approach from controlling lithium amount by physical doping parameters (temperature, time, concentration) to controlling it by chemical stoichiometry parameters (molar ratios, compound composition). This parameter change from physical to chemical control enables precise and reproducible lithium quantification.
3Quantity of substance
If using silicon oxides or silicates as negative electrode material to achieve high capacity, then theoretical capacity is improved, but irreversible lithium reaction occurs during initial charge
Solution Approach 1:
The patent converts the harmful irreversible lithium reaction into a beneficial process by intentionally designing the positive electrode with excess lithium compounds. The irreversible reaction that was previously a loss is now a planned feature that depletes the compensation lithium reservoir, preventing subsequent capacity fading and improving long-term cycle stability.
Solution Approach 2:
The patent discards the compensation lithium in the positive electrode during the initial charge process through irreversible reaction, and recovers the benefit of this discarded lithium by preventing future capacity loss. The sacrificed lithium serves to stabilize the electrode structure and prevent subsequent degradation, effectively trading initial lithium for long-term capacity retention.
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 configuration enhances the energy density of secondary batteries while simplifying manufacturing and reducing production hurdles, improving charge/discharge cycle performance and rate properties.
Implementation Method 1
a positive electrode containing a metal oxide (X) represented by AxMeOy (wherein A is at least one or two species selected from Na and K, Me is at least one or two species selected from Ni and Cu, x satisfies 1.9≦x≦2.1, and y satisfies 1.9≦y≦2.1)
Implementation Method 2
when silicon oxides or complexes of silicon and silicon oxides are used as a negative electrode, Li—Si—O compounds are formed during an initial charge process
Implementation Method 3
a negative electrode containing a negative electrode active material having an initial charge/discharge efficiency of 75% or less when charged and discharged by employing metallic Li as a counter electrode
Data Source
AI summary
Provided is a nonaqueous electrolytic solution secondary battery having a high energy density, and a positive electrode and a negative electrode used therefor. The nonaqueous electrolytic solution secondary battery includes a positive electrode and a negative electrode, wherein: the negative electrode contains a negative electrode active material having an initial charge/discharge efficiency of 75% or less when charged and discharged by employing metallic Li as a counter electrode; and the positive electrode contains a metal oxide (X) represented by AxMeOy (wherein A is Na and/or K, Me is Ni and/or Cu, x satisfies 1.9≦x≦2.1, and y satisfies 1.9≦y≦2.1).