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Lithium‐ion batteries (LIBs) have gained widespread attention due to their numerous advantages, including high energy density, prolonged cycle life, and environmental friendliness. Nevertheless, their electrochemical performance deteriorates rapidly under extreme temperature conditions, accompanied by a series of safety issues. Electrolyte optimization has emerged as a crucial and feasible strategy to expand the operational temperature range of LIBs. This review comprehensively summarizes the challenges, advances, and characterization methodologies of electrolytes at both subzero and elevated temperatures. Initially, it discusses the degradation mechanisms of different types of electrolytes at extreme temperatures, integrates recent advances, and offers insights into future research directions. Subsequently, various experimental techniques are systematically presented to evaluate the fundamental physical properties, stability, and dynamic behaviors of electrolytes in non‐ambient environments. Finally, it also provides relevant computational methods across the electronic, molecular, and macroscopic scales, and explores the application of high‐throughput techniques in this field. This review offers valuable guidance for breaking the working temperature limits of electrolytes and promoting the development of next‐generation LIBs. [ABSTRACT FROM AUTHOR]

The polysulfide (PS) dissolution and low conductivity of lithium sulfides (Li2S) are generally considered the main reasons for limiting the reversible capacity of the lithium‐sulfur (Li‐S) system. However, as the inevitable intermediate between PSs and Li2S, lithium disulfide (Li2S2) evolutions are always overlooked. Herein, Li2S2 evolutions are monitored from the operando measurements on the pouch cell level. Results indicate that Li2S2 undergoes slow electrochemical reduction and chemical disproportionation simultaneously during the discharging process, leading to further PS dissolution and Li2S generation without capacity contribution. Compared with the fully oxidized Li2S, Li2S2 still residues at the end of the charging state. Therefore, instead of the considered Li2S and PSs, slow electrochemical conversions and side chemical reactions of Li2S2 are the determining factors in limiting the sulfur utilization, corresponding to the poor reversible capacity of Li‐S batteries. [ABSTRACT FROM AUTHOR]

Abstract: Mn3O4 nanoparticles anchored on continuous super-aligned carbon nanotube (SACNT) films are synthesized by decomposition of Mn(NO3)2. In the Mn3O4/SACNT composite electrodes, SACNT film is capable of serving as both the conductive pathway and structural scaffold, therefore no binder, extra conductive agent, or current collector is needed. The electrochemical performance of the Mn3O4/SACNT composite electrode is significantly affected by the particle size of Mn3O4. With smaller particle size, the electrode displays smaller voltage hysteresis and much improved reversibility and rate capability. The Mn3O4/SACNT electrodes with particle size of Mn3O4 less than 10 nm show a capacity retention of 95% after 100 cycles at 1 C and a high rate capacity of 342 mAh g−1 at 10 C (based on the total mass of the electrode), suggesting their advantages over the commercial graphite anode and potential in practical applications. [Copyright &y& Elsevier]

Lithium-ion batteries (LIBs) are paramount in energy storage in consumer electronics and electric vehicles. However, a narrow operating temperature range severely constrains their evolution. In this study, a wide-temperature operating LIB system is constructed utilizing carbon nanotube (CNT)-based electrodes and a "constructive alliance" electrolyte. The unique microstructure of the CNT current collector, with high electrical and thermal conductivity, accelerates the reaction kinetics of active materials at subzero temperatures and optimizes the thermal management of the entire electrode at elevated temperatures. Furthermore, a strategy employing the "constructive alliance" electrolyte is proposed, demonstrating that a simple combination of commercially available electrolytes can enhance resilience to harsh thermal conditions. Molecular dynamics simulations and density functional theory calculations reveal that the hybrid electrolyte predominantly adopts aggregate solvation structures and possesses low Li + desolvation barriers regardless of thermal variations. Consequently, the assembled Li 4 Ti 5 O 12 //LiCoO 2 full cell, with a negative/positive electrode material ratio of 1.2, exhibits outstanding electrochemical performance in the wide temperature range of -40 and 60 °C. This innovative strategy overcomes challenges in wide-temperature electrolyte research and offers promise for next-generation wide-temperature LIBs., (© 2024 Wiley‐VCH GmbH.)

The polysulfide (PS) dissolution and low conductivity of lithium sulfides (Li 2 S) are generally considered the main reasons for limiting the reversible capacity of the lithium-sulfur (Li-S) system. However, as the inevitable intermediate between PSs and Li 2 S, lithium disulfide (Li 2 S 2 ) evolutions are always overlooked. Herein, Li 2 S 2 evolutions are monitored from the operando measurements on the pouch cell level. Results indicate that Li 2 S 2 undergoes slow electrochemical reduction and chemical disproportionation simultaneously during the discharging process, leading to further PS dissolution and Li 2 S generation without capacity contribution. Compared with the fully oxidized Li 2 S, Li 2 S 2 still residues at the end of the charging state. Therefore, instead of the considered Li 2 S and PSs, slow electrochemical conversions and side chemical reactions of Li 2 S 2 are the determining factors in limiting the sulfur utilization, corresponding to the poor reversible capacity of Li-S batteries., (© 2023 Wiley-VCH GmbH.)

Ultrathin and flexible layers containing BaTiO 3 (BTO) nanoparticles, graphene oxide (GO) sheets, and carbon nanotube (CNT) films (BTO/GO@CNT) are used to trap solvated polysulfides and alleviate the shuttle effect in lithium-sulfur (Li-S) batteries. In the functional layers, the CNT films build a conductive framework, and the GO sheets form a support membrane for the uniform dispersion of BTO nanoparticles. BTO nanoparticles without ferroelectricity (nfBTO) can trap polysulfides more effectively by chemical interaction compared to BTO nanoparticles with ferroelectricity (fBTO). A Li-S cell with the nfBTO/GO@CNT functional layer exhibits a reversible capacity of 824.5 mA h g -1 over 100 cycles at 0.2 C. At a high sulfur loading of 5.49 mg cm -2 , an electrode with the functional layer shows an areal capacity of 5.15 mA h cm -2 at 0.1 C, demonstrating the nfBTO/GO@CNT functional layer's potential in developing high-performance Li-S batteries.

Black phosphorus (BP) is a promising electrode material with high energy density for lithium-ion batteries. However, volumetric expansion of BP upon lithiation leads to rapid capacity fading of the electrode. Herein, BP composite electrodes are prepared by mixing microsized BP particles with carbon nanotubes and KetjenBlack as dual conducting agents, which facilitate the construction of stable and conductive networks in the electrodes. An ultrathin TiO 2 nanocoating is deposited on the surface of the BP composite electrode by electron-beam evaporation. The TiO 2 nanocoating acts as a protective layer to prevent the BP particles from directly contacting the electrolyte by forming a Li x Ti y O z passivation coating on the electrode surface. The Li x Ti y O z passivation layer suppresses propagation of the formed irreversible solid electrolyte interlayer on the BP particles, resulting in an improved Coulombic efficiency of the BP electrode. Moreover, the Li x Ti y O z passivation layer facilitates lithium-ion diffusion and electron transfer and thus superior cycling and rate performance of the BP electrode are achieved.