Solid-state lithium batteries may provide increased energy density and improved safety compared with Li-ion technology.However,in a solid-state composite cathode,mechanical degradation due to repeated cathode volume c...Solid-state lithium batteries may provide increased energy density and improved safety compared with Li-ion technology.However,in a solid-state composite cathode,mechanical degradation due to repeated cathode volume changes during cycling may occur,whichmay be partially mitigated by applying a significant,but often impractical,uniaxial stack pressure.Herein,we compare the behavior of composite electrodes based on Li4Ti5O12(LTO)(negligible volume change)and Nb2O5(+4%expansion)cycled at different stack pressures.The initial LTO capacity and retention are not affected by pressure but for Nb2O5,they are significantly lower when a stack pressure of<2MPa is applied,due to inter-particle cracking and solid-solid contact loss because of cyclic volume changes.Thiswork confirms the importance of cathode mechanical stability and the stack pressures for long-term cyclability for solid-state batteries.This suggests that low volumechange cathode materials or a proper buffer layer are required for solid-state batteries,especially at low stack pressures.展开更多
基金Henry Royce Institute,Grant/Award Numbers:FIRG007,EP/R0066X/1,FIRG008Engineering and Physical Sciences Research Council,Grant/Award Number:EP/M009521/1National Natural Science Foundation of China,Grant/Award Number:22309110。
文摘Solid-state lithium batteries may provide increased energy density and improved safety compared with Li-ion technology.However,in a solid-state composite cathode,mechanical degradation due to repeated cathode volume changes during cycling may occur,whichmay be partially mitigated by applying a significant,but often impractical,uniaxial stack pressure.Herein,we compare the behavior of composite electrodes based on Li4Ti5O12(LTO)(negligible volume change)and Nb2O5(+4%expansion)cycled at different stack pressures.The initial LTO capacity and retention are not affected by pressure but for Nb2O5,they are significantly lower when a stack pressure of<2MPa is applied,due to inter-particle cracking and solid-solid contact loss because of cyclic volume changes.Thiswork confirms the importance of cathode mechanical stability and the stack pressures for long-term cyclability for solid-state batteries.This suggests that low volumechange cathode materials or a proper buffer layer are required for solid-state batteries,especially at low stack pressures.
