Zhou Haoshen from Nanjing University and Chang Zhi from Central South University, "Nature Commun.: A new approach to improving the performance of high-voltage lithium metal batteries!

The rapid development of portable electronic devices and electric vehicles requires batteries with high energy density, long cycle life and fast charging performance. High-voltage positive electrode materials (such as LiNi₀.₈Co₀.₁Mn₀.₁O₂, i.e. NCM811) are expected to improve battery energy density, but they have poor stability and slow lithium ion diffusion in traditional electrolytes.

Basic Knowledge of Lithium Batteries - Second Part

 32.What is the IEC standard cycle life test?

 

IEC stipulates that the standard cycle life test for NiMH batteries is:

 

After the battery is discharged at 0.2C to 1.0V/piece

01) Charge at 0.1C for 16 hours, then discharge at 0.2C for 2 hours and 30 minutes (one cycle)

 

02) Charge at 0.25C for 3 hours and 10 minutes, discharge at 0.25C for 2 hours and 20 minutes (2-48 cycles)

 

03) Charge at 0.25C for 3 hours and 10 minutes, discharge at 0.25C to 1.0V (49th cycle)

 

04) Charge at 0.1C for 16 hours, leave for 1 hour, and discharge at 0.2C to 1.0V (50th cycle). For NiMH batteries, repeat 1-4 for a total of 400 cycles, and the 0.2C discharge time should be greater than 3 hours; for NiCd batteries, repeat 1-4 for a total of 500 cycles, and the 0.2C discharge time should be greater than 3 hours.

Basic Knowledge of Lithium Batteries - First Part

 I. Some important concepts

Lithium iron phosphate battery (LFP) and ternary lithium battery (NCM/NCA) are two mainstream lithium-ion battery technologies. The following are their main differences:

Lithium battery industry terms and explanations

 Lithium-ion battery: A battery that uses materials that can undergo lithium ion embedding/de-embedding reactions as positive and negative active materials, and uses organic electrolytes or polymer electrolytes containing lithium salts. It is a secondary battery (i.e., a rechargeable battery) that mainly relies on the movement of lithium ions between the positive and negative electrodes to work.

Lithium Battery Cell Production Process

A battery cell is the smallest unit of a battery system. Multiple battery cells form a module, and multiple modules form a battery pack. This is the basic structure of a car power battery. A battery is like a container for storing electrical energy. The amount of capacity it can store is determined by the amount of active material covered by the positive and negative electrodes. The design of the positive and negative electrode plates needs to be tailored to different models. The gram capacity of the positive and negative electrode materials , the ratio of active materials, the thickness of the electrode plates, the compaction density, etc. are also crucial to the capacity.

Comparative Study of Titanium 32×MXene Coated Carbon Electrodes and Thermally Treated Carbon Electrodes for Vanadium Redox Flow Batteries in RSC Advances

1.Research Background

A major challenge in vanadium redox flow batteries is the competition between the main and side reactions of hydrogen evolution associated with the V(II)/V(III) redox couple at the negative electrode.

Lithium Battery Negative Electrode Lithium Deposition Causes and Solutions

1.What is Lithium Deposition on the Negative Electrode?

The lithium intercalation potential of graphite is between 65–200 mV (vs. Li+/Li0). When the potential of the negative electrode approaches or drops below the deposition potential of metallic lithium, lithium ions will be deposited as metallic lithium on the surface of the negative electrode. Experiments have shown that during the charging process, some lithium ions are deposited as metallic lithium on the surface of the negative electrode, while the remaining lithium ions intercalate into the graphite or other negative electrode materials. During discharge, both ion de-intercalation and the stripping of deposited lithium metal occur simultaneously. In the process of lithium metal stripping, "dead lithium" is formed.

In short, the phenomenon of lithium deposition on the negative electrode refers to the simultaneous intercalation and deposition of lithium ions during the charge and discharge processes, causing lithium to deposit as metallic lithium on the surface of the negative electrode, and resulting in the formation of "dead lithium" that cannot be reused.

Design of Electrolyte for Achieving 4.8V-Class NCM811-Lithium Metal Batteries in Angew

1.Research Abstract

Combining high-voltage nickel-rich cathodes with lithium metal anodes is one of the most promising approaches to achieving high-energy-density lithium batteries. However, most current electrolytes cannot simultaneously meet the requirements for compatibility with lithium metal anodes and tolerance for ultra-high-voltage NCM811 cathodes. In this study, by adjusting the composition of fluorinated carbonate-based electrolytes, an ultra-anti-oxidative electrolyte was designed. The research found that through the synergistic decomposition of fluorinated solvents and PF6- anions, an SEI (solid electrolyte interphase) rich in LiF and Li2O was constructed on the lithium anode, which facilitated smooth deposition of lithium metal. More importantly, this electrolyte exhibited excellent antioxidant properties, enabling Li||NCM811 coin cells to maintain 80% of their capacity after 300 cycles at an ultra-high cut-off voltage of 4.8 V. Furthermore, under harsh conditions of high cathode loading (30 mg cm-2), low N/P ratio (1.18), and lean electrolyte (2.3 g Ah-1), a 4.8 V-class lithium metal pouch cell with an energy density of 462.2 Wh kg-1 could stably cycle for 110 times.