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The anion chemistry of lithium salts plays a pivotal role in dictating the physicochemical and electrochemical performance of solid polymer electrolytes (SPEs), thus affecting the cyclability of all‐solid‐state lithium metal batteries (ASSLMBs). The bis(trifluoromethanesulfonyl)imide anion (TFSI−) has long been studied as the most promising candidate for SPEs; however, the Li‐ion conductivities of the TFSI‐based SPEs still remain low (Li‐ion transference number: ca. 0.2). In this work, we report new hydrogen‐containing anions, conceived based on theoretical considerations, as an electrolyte salt for SPEs. SPEs comprising hydrogen‐containing anions achieve higher Li‐ion conductivities than TFSI‐based ones, and those anions are electrochemically stable for various kinds of ASSLMBs (Li–LiFePO4, Li–S, and Li–O2 batteries). This opens up a new avenue for designing safe and high‐performance ASSLMBs in the future.

Owing to resource abundance, and hence, a reduction in cost, wider global distribution, environmental benignity, and sustainability, sodium-based, rechargeable batteries are believed to be the most feasible and enthralling energy-storage devices. Accordingly, they have recently attracted attention from both the scientific and industrial communities. However, to compete with and exceed dominating lithium-ion technologies, breakthrough research is urgently needed. Among all non-electrode components of the sodium-based battery system, the electrolyte is considered to be the most critical element, and its tailored design and formulation is of top priority. The incorporation of a small dose of foreign molecules, called additives, brings vast, salient benefits to the electrolytes. Thus, this review presents progress in electrolyte additives for room-temperature, sodium-based, rechargeable batteries, by enlisting sodium-ion, Na-O /air, Na-S, and sodium-intercalated cathode type-based batteries.

Solid-state lithium metal (Li°) batteries (SSLMBs) are believed to be the most promising technologies to tackle the safety concerns and the insufficient energy density encountered in conventional Li-ion batteries. Solid polymer electrolytes (SPEs) inherently own good processability and flexibility, enabling large-scale preparation of SSLMBs. To minimize the growth of Li° dendrites and cell polarization in SPE-based SSLMBs, an additive-containing single Li-ion conductive SPE is reported. The characterization results show that a small dose of electrolyte additive (2 wt%) substantially increases the ionic conductivity of single Li-ion conductive SPEs as well as the interfacial compatibility between electrode and SPE, allowing the cycling of SPE-based cells with good electrochemical performance. This work may provide a paradigm shift on the design of highly cationic conductive electrolytes, which are essential for developing safe and high-performance rechargeable batteries.wind, solar). [4] The widely used LIBs comprise a graphitized material and a lithium transition metal oxide as the respective negative and positive electrodes, and a carbonate-based liquid solution as electrolyte. [5] On one side, the high volatility and flammability of carbonate solvents causes severe safety issues when LIBs are under abusive conditions, as noted by the increasing incidents of smartphones, EVs, and stationary batteries. [6] On the other side, the pursuit of higher energy density in battery technologies, due to the demanding requirements in newly emerging applications, has spurred considerable interest in replacing carbonaceous materials with higher capacity Li metal (Li°) electrode (e.g., 3860 mAh g -1 (Li°) vs 372 mAh g -1 (graphite)). Yet, the practical implementation of rechargeable Li°-based batteries using liquid electrolytes is handicapped by the notorious Li° dendrite formation, which results in not only low energy efficiency but also possible internal short-circuit and subsequent thermal runaway. [7] To mitigate aforementioned safety concerns and break the ceiling of energy density in LIB technologies, solid polymer electrolyte (SPE)-based solid-state Li° batteries (SSLMBs) have garnered great attention from both academic and industrial sectors. [8] Since the first perceptive proposal on using SPEs as safe electrolytes for rechargeable batteries by Armand and Duclot in 1978, [9] significant progresses and advances have been achieved in the field. [10] SPE-based batteries have been proven to be technologically feasible by the expanding applications of lithium metal polymer batteries developed by Bolloré group in EV cars and buses, as well as other energy storage scenarios. [11] However, the commonly employed conducting salt lithium bis(trifluoromethanesulfonyl)imide {Li[N(SO 2 CF 3 ) 2 ], LiTFSI} possesses a high anionic mobility (i.e., low Li-ion transference number, <0.3 [12] ) in poly(ethylene oxide) (PEO), engendering pronounced cell polarization and rapid Li° dendrite growth upon cycling of SSLMBs, particularly when...