High-Voltage Li-Ion Cathode-Electrolyte Interface for Longer Cycle Life
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Solution Overview
Problem
Existing high-voltage lithium ion batteries face issues with structural damage, metal ion dissolution, gas expansion, and electrolyte decomposition, leading to reduced cycle life and safety performance due to the lack of effective electrolyte additives that cooperate with positive electrode materials.
Innovation Solution
A lithium ion battery design incorporating a positive electrode active material of LixNiyCozM1-y-zO2 doped or coated with elements like Ba, Zn, Ti, Mg, Zr, W, Y, Si, Sn, B, or P, and an electrolyte additive represented by structural formula 1, regulated within specific mass content and thickness ratios, forms a stable interface film to inhibit electrolyte oxidation and improve cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the working voltage is increased to improve energy density, then the energy density is improved, but the structure of the layered oxide material is damaged causing metal ion dissolution and reduced cycle life
Solution Approach 1:
The patent applies preliminary action by pre-coating the positive electrode material surface with aluminum oxide before battery operation. This pre-formed protective layer prevents structural damage and metal ion dissolution during high-voltage charging, thereby extending cycle life while maintaining high energy density. The coating is applied in advance to protect against future degradation.
Solution Approach 2:
The aluminum oxide coating acts as an intermediary layer between the positive electrode material and the electrolyte. This intermediate layer protects the layered oxide material from direct contact with the electrolyte, preventing metal ion dissolution and structural damage while allowing lithium ion transport, thus resolving the contradiction between high voltage operation and cycle stability.
2Use of energy by moving object
If the working voltage is increased to improve energy density, then the energy density is improved, but gas expansion occurs affecting safety performance
Solution Approach 1:
The aluminum oxide coating is applied in advance to the positive electrode material surface before battery assembly and operation. This pre-formed protective barrier prevents gas-generating side reactions between the electrolyte and electrode material during high-voltage charging, thereby suppressing gas expansion while enabling high energy density operation.
Solution Approach 2:
The aluminum oxide layer serves as an intermediary barrier that prevents direct interaction between the electrolyte and positive electrode material. This intermediate protection layer eliminates harmful gas expansion caused by electrolyte decomposition at high voltage, while maintaining the high energy density benefits of elevated operating voltage.
3Reliability
If existing high-voltage electrolyte additives are used to improve high-voltage resistance, then the electrolyte stability is improved, but the interface film formed increases electrode interface impedance
Solution Approach 1:
The patent changes the parameter of the protective layer material from conventional coating materials to aluminum oxide specifically. This parameter change results in a protective layer that provides both high-voltage resistance and low interface impedance, as aluminum oxide forms a stable yet conductive interface that allows efficient lithium ion transport while protecting against electrolyte decomposition.
Solution Approach 2:
The patent creates a composite structure consisting of the positive electrode material combined with an aluminum oxide coating layer. This composite material integrates the high capacity characteristics of the layered oxide with the protective and conductive properties of aluminum oxide, achieving both high-voltage resistance and low interface impedance simultaneously.
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 synergistic effect of the additive and doping/coating enhances the interface film's compactness, reducing impedance and improving high-temperature cycle stability and safety of the battery.
Implementation Method 1
the additive includes a compound represented by structural formula 1... which can form a stable and compact interface film at high voltage on the surface of the positive electrode material, which can effectively inhibit the oxidative decomposition of the electrolyte
Implementation Method 2
by providing coated or doped elements in the positive electrode material, the structure of the layered lithium-nickel-based oxide material can be effectively passivated, the oxidation decomposition of the electrolyte on the surface of the positive electrode material can be inhibited
Data Source
AI summary
A lithium ion battery includes a positive electrode containing a positive electrode material layer, a negative electrode and a non-aqueous electrolyte, the positive electrode material layer comprises a positive electrode active material, the positive electrode active material comprises LixNiyCozM1-y-zO2, M is at least one element selected from Mn and Al, the positive electrode active material is doped or coated with an element E, the element E is selected from one or more of Ba, Zn, Ti, Mg, Zr, W, Y, Si, Sn, B, Co, and P, a potential range of the positive electrode active material with respect to lithium metal is ≥4.25V; the non-aqueous electrolyte comprises a solvent, an electrolyte salt and an additive, the additive comprises a compound represented by structural formula 1:and the lithium ion battery meets the following requirements: 0.1≤(H/T)×M/1000≤10; and 80≤H≤150, 0.005≤T≤0.8, 0.05≤M≤3.