Abstract
As a well-established method, neutron diffraction has been widely adopted to characterize the atomic structure of materials. One of the most distinct advantages of neutron diffraction refers to its high sensitivity to most light elements (e.g., lithium), which could distinguish isotopes and identify adjacent elements. Moreover, magnetic structure may also be probed. More importantly, the penetration depth of neutrons is thick enough for battery detection with centimeter scales. For secondary batteries, neutron diffraction has shown advantages in determining phase structure and ion diffusion in active materials, which are critical issues in battery studies due to the dominant charge and energy transport functions of active ions. Moreover, neutron diffraction also exhibits superior performance in revealing lithium coordinates in lattice and related occupations, as well as visualizing the diffusion path of lithium atoms, which may not be completed via other characterizations. This chapter aims to comprehensively review the working mechanism and main research progress of neutron diffraction in secondary batteries. The essential background, working principle and practical applications of neutron diffraction on the cathode, anode, solid-state electrolytes and full batteries, as well as its data analysis, are introduced and discussed.