최근, 교수 장 치앙's 팀 에서 the 부서 의 화학 공학 at 칭화 대학 출판 the 연구 결과 on the bulk/surface interface structure design of lithium-rich mangane-based angese-based cathode materials for all-solid-state metal lithium batteries. They proposed an in-situ bulk/surface interface structure regulation strategy, constructed a fast and stable Li+/e−pathway, and promoted the practical application of lithium-rich manganese-based cathode materials in all-solid-state lithium batteries.
Batteries play a vital role in the modern energy field and have achieved great success in portable electronic devices, electric vehicles, and grid-scale energy storage applications. However, while improving the energy density of batteries, ensuring the safety of batteries is the key. With the rapid growth of the demand for improving the energy density of batteries, the traditional lithium-ion battery technology that relies on traditional cathode materials and organic electrolytes has encountered technical bottlenecks in long-term cycle stability, wide temperature range, and safety. Compared with traditional lithium-ion batteries, all-solid-state lithium batteries can break through the higher energy density limit. Due to its excellent energy density and safety characteristics, it has also become the most promising next-generation battery technology. Despite this, classic cathode materials cannot currently meet the high energy density and safety requirements of all-solid-state lithium batteries. Lithium-rich manganese-based cathode materials have become the most promising cathode materials for all-solid-state lithium batteries due to their discharge specific capacity Greater than or equal to 250 mAh/g, energy density Greater than or equal to 1000 Wh/kg, and low Co and Ni content.
그러나, due to the low electronic conductivity and obvious irreversible redox reaction, the interface structure is severely degraded, which makes the kinetic behavior of lithium-rich manganese-based cathode materials during charge and discharge impaired. 산소 탈출 현상 엑서베이트 이 인터페이스 실패 행동, 선행 to 산화 분해 of the 전해질, which in turn 파괴 the interface stability between 리튬이 풍부 망간 음극 재료 및 전해질.
구성 및 유지 a 안정 Li+ 및 e−운송 경로 for the 배터리 in working 상태 is the 전제조건 for promoting the long cycle of all-solid-state batteries under practical conditions. The research team can construct a stable and fast Li+/e−pathway in situ at the cathode material/solid electrolyte interface by adjusting the bulk/surface interface structure and innovative design, promote the redox reaction activity of 음이온 산소, and enhance the reversibility of the 산화환원 반응 음이온 산소 on the 표면 의 the 음극 재료 of 전고체 리튬 배터리 at 방 온도, 그에 의해 안정화 높은 전압 단단하고 단단한 인터페이스.
그림 1. 회로도 다이어그램 의 the 수정 의 부피/표면 인터페이스 구조 설계 전략 의 리튬이 풍부한 망간계 음극 재료
This study proposed a one-step synthesis strategy to optimize the bulk/surface interface structure of lithium-rich manganese-based cathode materials, and created a lithium-rich manganese-based cathode material (5W&LRMO) with a bulk embedded structure, W doping and Li2WO4 surface coating. This structure enhances the bulk structural stability of lithium-rich manganese-based cathode materials, improves the transfer kinetics of Li+/e−, and significantly enhances the redox activity of transition metal cations and anionic oxygen. Charge compensation of anionic oxygen redox reactions during the charge and discharge process is achieved, thereby promoting the reversibility of oxygen ion redox reactions on the surface of lithium-rich manganese-based cathode materials and stabilizing the high-voltage solid-solid interface. The optimized interface ensures charge and discharge stability in the high voltage range and maintains efficient Li+/e−transfer kinetics over a long cycle period, thereby improving the utilization rate of active substances in the composite cathode material.
그림 2. 진화 of interfacial Li+ transport kinetics of 리튬이 풍부한 망간계 음극 재료 동안 the 첫번째 충전 및 방전 공정
This study revealed the impedance evolution process of the interface between the lithium-rich manganese-based cathode and the electrolyte by in-situ impedance spectroscopy (EIS) testing combined with relaxation time analysis (DRT). The proposed method enables visualization of the interface evolution process during the first charge and discharge and long cycle process. The study deeply understands the interface structure evolution between the lithium-rich manganese-based cathode material and the electrolyte before and after modification. It is found that the lithium-rich manganese-based cathode material before modification exhibits irreversible anion oxygen redox reaction at high voltage, further oxidizing the cathode and electrolyte interface, resulting in a significant increase in impedance and hindering the interfacial Li+ transmission. In contrast, the modified lithium-rich manganese-based cathode material exhibits stable/fast Li+ diffusion kinetics, especially at a high voltage of 4.6 V, minimizing the change in interfacial impedance value. Therefore, faster and more stable interfacial Li+ transmission is promoted by improving the reversibility of anion oxygen redox reaction. It is easier for composite cathode materials to achieve industrial-grade applications with a surface capacity of ~3 mAh/cm2 or even higher. At 25 degree , the surface capacity of the high-area-load 5W&LRMO cathode material at 0.2 C rate is about 2.5 mAh/cm2, and the capacity retention rate is 88.1% after 100 cycles; at a high rate of 1 C, it shows ultra-long cycle stability, with a capacity retention rate of 84.1% after 1200 cycles. The research provides a new way to design the bulk/surface interface structure of lithium-rich manganese-based cathode materials and an effective way to improve the energy density of all-solid-state lithium batteries.
On October 1, the relevant research results were published in the Journal of the American Chemical Society under the title"Bulk/Interfacial Structure Design of Li-Rich Mn-based Cathodes for All-solid-State Lithium Batteries".
토브 새롭게 에너지 제공 a 전체 설정 of solid-state battery solutions솔리드 스테이트 배터리 재료, 솔리드 스테이트 배터리 장비, 및 솔리드 스테이트 배터리 생산 라인 솔루션.
