Abstract: Aspects disclosed herein include materials comprising: a lithium thioborate composition characterized by formula FX1: Li3?z[B+Q]1[S+G]3 (FX1); wherein Q is a first dopant being a substitute for B in the composition and being one or more elements each aliovalent with respect to B; wherein G is a second dopant being a substitute for S in the composition and being one or more elements each aliovalent with respect to S; wherein z is a number greater than 0 and less than or equal to 0.40, optionally less than or equal to 0.05; and wherein the composition comprises only the first dopant, only the second dopant, or both the first dopant and the second dopant.

Abstract: Provided herein are compositions, devices, electrochemical systems, and methods relating to lithium-rich iron sulfide lithium-ion battery cathodes. In one embodiment, a composition may be characterized by formula FX1: Liw-?AlxFezS2. In some embodiments, w may be greater than or equal to 2 and less than or equal to 2.5. In some embodiments, x may be greater than 0 and less than or equal to 0.5. In some embodiments, z may be greater than 0 and less than or equal to 1. In some embodiments, ? may be greater than or equal to 0 and less than w. In some embodiments, the composition may have a net charge of 0.

Abstract: In an aspect, an electrochemical cell comprises: a positive electrode; a negative electrode; and a solid state electrolyte in ionic communication with the positive electrode and the negative electrode; wherein: the electrolyte is characterized by formula (FX1): MPS3 (FX1); wherein M is one or more metal cations and optionally metal cation vacancies; and wherein at least one of said one or more metal cations is a divalent cation; the electrolyte is characterized by a divalent ion conductivity; and the electrolyte is electrically insulating. The solid state electrolyte is optionally not an electrocatalyst material or does not function as an electrocatalyst in the electrochemical cell during operation (e.g., charging and/or discharging) of the electrochemical cell. The solid state electrolyte is optionally not an electrode or does not function as an electrode in the electrochemical cell during operation (e.g., charging and/or discharging) of the electrochemical cell.

Abstract: In an aspect, an electrochemical cell comprises: a positive electrode; a negative electrode; and a solid state electrolyte in ionic communication with the positive electrode and the negative electrode; wherein: the electrolyte is characterized by formula (FX1): MPS3 (FX1); wherein M is one or more metal cations and optionally metal cation vacancies; and wherein at least one of said one or more metal cations is a divalent cation; the electrolyte is characterized by a divalent ion conductivity; and the electrolyte is electrically insulating. The solid state electrolyte is optionally not an electrocatalyst material or does not function as an electrocatalyst in the electrochemical cell during operation (e.g., charging and/or discharging) of the electrochemical cell. The solid state electrolyte is optionally not an electrode or does not function as an electrode in the electrochemical cell during operation (e.g., charging and/or discharging) of the electrochemical cell.

Abstract: In an aspect, an electrochemical cell comprises: a positive electrode; a negative electrode; and a solid state electrolyte in ionic communication with the positive electrode and the negative electrode; wherein: the electrolyte is characterized by formula (FX1): MPS3 (FX1); wherein M is one or more metal cations and optionally metal cation vacancies; and wherein at least one of said one or more metal cations is a divalent cation; the electrolyte is characterized by a divalent ion conductivity; and the electrolyte is electrically insulating. The solid state electrolyte is optionally not an electrocatalyst material or does not function as an electrocatalyst in the electrochemical cell during operation (e.g., charging and/or discharging) of the electrochemical cell. The solid state electrolyte is optionally not an electrode or does not function as an electrode in the electrochemical cell during operation (e.g., charging and/or discharging) of the electrochemical cell.