https://interestingengineering.com/energy/battery-innovation-doubles-energy-density
EV battery cells get double power boost, 60% energy density with new trick
This study offers a new direction for next-generation energy storage systems.
Scientists have implemented a novel method to successfully overcome a major limitation of conventional lithium-ion batteries (LIBs) and increase the energy density of cells. Researchers from South Korea dealt with unstable interfaces between electrodes and electrolytes.
Researchers believe that silicon-based batteries could be better alternative to graphite-based batteries, which are currently majorly used in smartphones and laptops. This is because graphite falls short on energy capacity while silicon can store nearly ten times more lithium ions. Therefore, silicon can be promising next-generation anode material.
Dramatic volume expansion and contraction
However, researchers highlighted that silicon's main drawback is its dramatic volume expansion and contraction during charge and discharge, swelling up to three times its original size. This repeated expansion and contraction causes mechanical gaps between the electrode and the electrolyte, quickly degrading battery performance.
Researchers planned to address this issue by replacing liquid electrolytes with solid or quasi-solid-state electrolytes (QSSEs), which offer better safety and stability.
Yet, QSSEs still struggle to maintain full contact with the expanding and contracting silicon, leading to separation and performance loss over time.
New direction for next-generation energy storage systems
"This study offers a new direction for next-generation energy storage systems that simultaneously demand high energy density and long-term durability," said Professor Soojin Park of POSTECH, who co-led the study.
The research team from POSTECH and Sogang University worked on the IEE system that forms covalent chemical bonds between the electrode and electrolyte.
Researchers revealed that, unlike conventional batteries, where components merely touch, the IEE system bonds the two into a chemically entangled structure, like bricks held together by hardened mortar, so they remain tightly connected even under intense mechanical stress.
"The in situ Interlocking Electrode–Electrolyte (IEE) strategy is a key technology that could accelerate the commercialization of silicon-based batteries by significantly enhancing interfacial stability," said Professor Jaegeon Ryu of Sogang University.
Electrochemical performance tests
Electrochemical performance tests showed a dramatic difference: while traditional batteries lost capacity after just a few charge-discharge cycles, those using the IEE design maintained long-term stability. Most notably, the IEE-based pouch cell demonstrated an energy density of 403.7 Wh/kg and 1300 Wh/L, representing over 60% greater gravimetric energy density and nearly twice the volumetric energy density compared to typical commercial LIBs, according to a press release.
Researchers underlined that in practical terms, this can help electric vehicles travel farther and smartphones operate longer using the same-sized battery.
The research's in situ interlocking electrode–electrolyte (IEE) system leverages covalent crosslinking between acrylate-functionalized interlocking binders on active materials and crosslinkers within the quasi-solid-state electrolyte (QSSE) to establish a robust, interconnected network that maintains stable electrode–electrolyte contact.
The research addresses the limitations of liquid electrolyte and QSSE configurations, evidenced by low voltage hysteresis in (de)lithiation peaks over 200 cycles, stable interfacial resistance throughout cycling, and the absence of void formation.
A pressure-detecting cell kit further confirms that the IEE system exhibits lower pressure changes during cycling without any voltage fluctuations from contact loss, according to the study.
The research was published in the journal Advanced Science.
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