Can't we have both endurance and safety? These two major interface challenges are broken by a Tsinghua team!

Recently, the Zhang Qiang Professor team from the Department of Chemical Engineering at Tsinghua University proposed a new strategy for designing anionic-rich solvent structures and successfully developed a novel fluorine-containing polyether electro

Battery energy density has been increased from the common range of 150-320 Wh kg⁻1 to 604 Wh kg⁻1, and has passed safety tests for punctures and exposure to high temperatures of 120℃.

The research findings were published online on September 24th in Nature, with the topic of Achieving 600 Wh kg⁻¹ lithium batteries by regulating the solvent structure of polymer electrolytes.

This research provides new ideas and technical support for the development of practical, high-safety and high-energy-density solid-state lithium batteries.

Zhang Qiang (third from the left) guiding students

How to crack the problem of solid-state battery interface?

Addressing the high energy and safety demands of dynamic systems in cutting-edge fields such as electric vehicles, electric aircraft, and humanoid robots, the development of battery components with high energy density and excellent safety performance

Solid-state batteries are widely regarded as an important development direction for the next generation of secondary lithium batteries due to their high energy density and inherent safety potential.

In particular, the solid-state battery system using lithium-rich manganese-based layered oxide as the positive electrode material exhibits the potential to achieve an energy density of over 600 Wh kg−1.

However, solid-state batteries still face two major interface challenges in practical applications.

The interface impedance between solid-solid materials is large due to rigid contact, and it is difficult for electrolytes to simultaneously accommodate the extreme chemical environments of high-voltage cathodes and strongly reducing anodes under wide

For example, the polymer component of the polyether electrolyte will undergo oxidative decomposition when the voltage is higher than 4.0 V (vs. Li/Li⁺), triggering persistent interface side reactions and performance degradation, which restrict its fu

In traditional solid-state battery design, high pressure (hundreds of atmospheres) is often applied or multiple layers of electrolyte are constructed to improve interface contact and compatibility.

However, high external pressure conditions are difficult to maintain stably in practical devices.

Complex multilayer structures can introduce new problems such as increased interface impedance, difficulties in interlayer matching, and poor ion transport, which limit the overall performance of the battery.

How to build a stable and efficient solid-solid interface while avoiding high external pressure and structural complexity has become a key scientific challenge in this field.

Batteries are safer and have higher energy density

In response to the above challenges, Professor Zhang Qiang's team proposed a new strategy for designing "rich anionic solvent structure" and successfully developed a new type of fluorine-containing polyether electrolyte.

The electrolyte effectively enhances the physical contact and ion conduction ability of the solid interface through in-situ polymerization technology induced by heat.

The team introduced strong electron-withdrawing fluorinated groups into the polyether electrolyte, significantly improving its high-pressure resistance, making it compatible with a 4.7 V high-voltage lithium-rich manganese-based cathode, and achievin

Based on the principle of lithium bonding chemistry, the team constructed a --F∙∙∙Li+∙∙∙O-- coordination structure, which induced the formation of an anion-rich solvent structure with high ion conductivity. This resulted in a stable interface layer e

Through the design of fluorinated polyether electrolytes, innovations have been achieved from molecular structure to interface performance: strong electron-withdrawing groups have broadened the voltage window; the lithium bond coordination structure

Thanks to optimized interface performance, the lithium-rich manganese-based polymer battery assembled with this electrolyte demonstrates excellent electrochemical performance, with an initial coulombic efficiency of 91.8%, a specific capacity of 290.

For comparison, the current commercialized lithium iron phosphate energy storage/power cells have an energy density of about 150~190 Wh kg-1, while the lithium nickel cobalt manganese oxide power cells have an energy density of about 240~320 Wh kg-1.

The all-cell performance of the fluorine-containing polyether electrolyte-based battery (a) is excellent: it maintains 72.1% capacity after 500 cycles at 0.5 C (b); the energy density of the 8.96 Ah soft-packed battery reaches 604 Wh kg⁻¹ (c), which

In its fully charged state, the battery has also passed the needle puncturing and 120°C heat box (resting for 6 hours) safety tests without any combustion or explosion, demonstrating excellent safety performance.

This research provides new ideas and technical support for the development of practical, high-safety and high-energy-density solid-state lithium batteries.

Huang Xueyan, a postdoctoral student in the Department of Chemical Engineering at Tsinghua University, is the first author of the paper, while Professor Zhang Qiang and Assistant Researcher Zhao Chenzhi from the same department are the corresponding

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