A medium-entropy transition metal oxide cathode for high-capacity lithium metal batteries

Abstract

The limited capacity of the positive electrode active material in non-aqueous rechargeable lithium-based batteries acts as a stumbling block for developing high-energy storage devices. Although lithium transition metal oxides are high-capacity electrochemical active materials, the structural instability at high cell voltages (e.g., >4.3 V) detrimentally affects the battery performance. Here, to circumvent this issue, we propose a Li1.46Ni0.32Mn1.2O4-x (0 < x < 4) material capable of forming a medium-entropy state spinel phase with partial cation disordering after initial delithiation. Via physicochemical measurements and theoretical calculations, we demonstrate the structural disorder in delithiated Li1.46Ni0.32Mn1.2O4-x, the direct shuttling of Li ions from octahedral sites to the spinel structure and the charge-compensation Mn3+/Mn4+ cationic redox mechanism after the initial delithiation. When tested in a coin cell configuration in combination with a Li metal anode and a LiPF6-based non-aqueous electrolyte, the Li1.46Ni0.32Mn1.2O4-x-based positive electrode enables a discharge capacity of 314.1 mA h g−1 at 100 mA g−1 with an average cell discharge voltage of about 3.2 V at 25 ± 5 °C, which results in a calculated initial specific energy of 999.3 Wh kg−1 (based on mass of positive electrode’s active material).

Toward Stable Cycling of a Cost‐Effective Cation‐Disordered Rocksalt Cathode via Fluorination

“…Such rocksalt to spinel-like phase transformation is reversible during discharge process as indicated by the disappearance of the spinel-like diffraction spots and reappearance of the features related to short-range ordering (Figure 3d). The change in the local structure and improved electrochemical performance are consistent with that observed for partial cationdisorder spinel-like phase, [14] which involves the occupancy of Li ions at the tetrahedral sites in the Li-rich compound. [14,15]…”

“…The change in the local structure and improved electrochemical performance are consistent with that observed for partial cationdisorder spinel-like phase, [14] which involves the occupancy of Li ions at the tetrahedral sites in the Li-rich compound. [14,15]…”

The heterointerface effect to boost the catalytic performance of single atom catalysts for sulfur conversion in lithium–sulfur batteries

“…Up to now, various materials have been investigated for use as electrodes including 2D carbonaceous materials, 23,24 metal sulfides, 25,26 metal oxides 27,28 and Mxenes. 29,30 This implies that the combination of SACs with such materials will give rise to a huge number of heterostructures given the various metal centers of SACs.…”

Lithium‐Ion Batteries Containing Surfactants for the Protection of Graphite Anode against the Passivation Layer Byproducts

“…In a nutshell, LIBs are typically based on a graphite negative electrode (with a theoretical specific capacity of 372 mAh g À 1 , anode) [1] and a lithium transition metal oxide positive electrode (cathode). [2] Commonly used linear or cyclic alkyl carbonates (that decrease the melting point and viscosity such as ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate) dissolved in the appropriate lithium-based salt (i. e., lithium hexafluorophosphate, LiPF 6 ) are electrochemically reduced at the anode surface during the initial cycles forming an insoluble passivating film known as the solid-electrolyte interphase (SEI). [3] The latter is a critical component of LIBs in that it prevents further electrolyte or solvent decomposition (i. e., SEI hinders electron tunnelling from the electrode [4] ), facilitates the Li + transport and adds stability and durability to the cell, namely the power capability, safety, and cycle life.…”

“…In a nutshell, LIBs are typically based on a graphite negative electrode (with a theoretical specific capacity of 372 mAh g −1 , anode) [1] and a lithium transition metal oxide positive electrode (cathode) [2] . Commonly used linear or cyclic alkyl carbonates (that decrease the melting point and viscosity such as ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate) dissolved in the appropriate lithium‐based salt (i. e., lithium hexafluorophosphate, LiPF 6 ) are electrochemically reduced at the anode surface during the initial cycles forming an insoluble passivating film known as the solid‐electrolyte interphase (SEI) [3] .…”