Multiphase Lithium Metal Oxide Cathode for Low Irreversible Capacity Loss
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Solution Overview
Problem
Lithium-ion batteries suffer from high irreversible capacity loss and cycling instability, limiting their energy density and lifespan, particularly in high-power applications like electric vehicles, due to the instability of lithium-rich layered materials and significant irreversible capacity losses during the initial charge-discharge cycle.
Innovation Solution
Development of multiphase lithium metal oxide compositions with specific stoichiometric ratios and structures, including a spinel phase, which exhibit low irreversible capacity loss and high specific discharge capacities, stabilized by inorganic coatings, to enhance cycling performance and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-rich layered materials are used to increase energy density, then the battery capacity is improved, but irreversible capacity loss increases significantly during the initial charge-discharge cycle
Solution Approach 1:
The patent applies composite materials by combining layered lithium metal oxide phases with spinel phases to create a multiphase cathode material. This composite structure allows the material to achieve high capacity (improving the quantity of substance) while the spinel phase provides structural stability that reduces irreversible capacity loss during initial cycling. The synergistic combination of different phases resolves the contradiction between high capacity and low irreversible loss.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the stoichiometric ratios and phase compositions in the lithium metal oxide material. By adjusting parameters such as lithium content, metal ratios (Ni, Co, Mn, and dopant M), and phase proportions, the material achieves optimal balance between high capacity and reduced irreversible capacity loss. The specific compositional parameters cited in the patent directly address this contradiction.
2Power
If high-power battery design is used to deliver high current, then power output is improved, but energy density is reduced
Solution Approach 1:
The patent applies universality by designing a cathode material that can serve multiple functions: it provides high power output capability through its electrochemical properties while simultaneously delivering high energy density through its high capacity. The multiphase lithium metal oxide material can operate effectively across a range of discharge rates, making it suitable for both high-power and high-energy applications, thus resolving the contradiction between power and energy density.
3Duration of action of stationary object
If lithium ion batteries are designed for longer cycling, then durability is improved, but the percentage of usable capacity decreases
Solution Approach 1:
The patent applies beforehand cushioning by incorporating a spinel phase into the lithium metal oxide structure prior to battery operation. This spinel phase acts as a cushioning element that provides structural stability and prevents degradation during cycling. The pre-formed stable phase structure cushions against the mechanical and chemical stresses of repeated charging/discharging, enabling long cycling life while maintaining high usable capacity percentage.
4Reliability
If inorganic coatings are applied to stabilize the material, then cycling stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the compositional parameters of the lithium metal oxide material itself to achieve inherent stability without requiring complex inorganic coatings. By adjusting the metal ratios, doping with element M, and controlling phase composition, the material achieves good cycling stability through its intrinsic properties, thereby avoiding the manufacturing complexity associated with applying and controlling thin inorganic coating layers.
Data Source
AI summary
Mixed phase complex lithium metal oxides are described with an overall stoichiometry represented by a formula Li1+aNibCocMndOx, −0.05≦a≦0.14, 0.1≦b≦0.25, 0≦c≦0.2, 0.45≦d≦0.8, a+b+c+d=1 and (1+a)/(b+c+d)≦1.325. The compositions are generally very high in manganese content. The compositions can have x-ray diffractograms and differential capacity profiles suggesting the presence of a layered (Li2MnO3)—layered (LiMetalO2)—spinel crystal structure. The compositions can exhibit surprisingly low first cycle irreversible capacity losses while maintaining high specific discharge capacities, even at high discharge rates. Stabilizing coatings have been found to further significantly improve performance.