Backgroud:
Researchers at the Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, have achieved a significant breakthrough in all-solid-state lithium batteries, potentially realising the dream of smaller electronic devices with extended battery life. This advancement was published in the international academic journal Nature Energy on 31st July.
Lithium-ion batteries used in mobile phones, computers and other electronic devices predominantly store and release energy via liquid electrolytes. Scientists are now exploring a novel battery type—all-solid-state lithium batteries. These utilise solid electrolytes instead of liquids, rendering them significantly safer.
While all-solid-state lithium batteries appear ideal, their development faces challenges. Primarily, the differing chemical and physical properties of materials within the battery's cathode make perfect compatibility difficult, leading to multiple interface issues that compromise energy density and lifespan. To address this, the research team developed a novel material: a homogenised cathode material (lithium titanium germanium phosphoselenide).
Compared to conventional materials, this compound offers advantages including high electrical conductivity, high energy density, and extended service life:
High electrical conductivity: This novel material exhibits both high ionic and electronic conductivity, surpassing traditional battery materials (layered oxide cathodes) by over 1000-fold. This enables smooth charging and discharging processes without relying on conductive additives, significantly enhancing overall battery performance.
High discharge capacity: The new material exhibits a high discharge capacity of 250 mAh per gram, surpassing currently used high-nickel cathode materials. At equivalent weight or volume, batteries incorporating this material can store greater electrical energy. This not only enables longer sustained operation without frequent recharging, thereby enhancing endurance, but also reduces battery size, facilitating the design of more compact devices.
Low Volume Change: During charging and discharging cycles, the new material exhibits a volume change of merely 1.2%, substantially lower than the 50% observed in conventional layered oxide cathode materials. This minimal volume change helps maintain structural stability, thereby extending the battery's operational lifespan.
High energy density: All-solid-state lithium batteries utilising this novel material achieve an energy density of 390 Wh/kg, representing a 1.3-fold increase over previously reported long-cycle all-solid-state lithium batteries.
Extended Service Life: All-solid-state lithium batteries employing this material achieve over 10,000 cycles. After 5,000 charge cycles, the battery retains 80% of its initial capacity, delivering ample power for extended periods.
This research provides crucial technical support for developing high-energy-density, long-life energy storage devices, offering safe and durable power sources for new energy vehicles, energy storage grids, and deep-sea/deep-space equipment. It holds significant implications for advancing novel energy storage systems.