The applicability of organic battery materials in conventional rocking-chair Li-ion cells remains deeply challenged by the lack of lithium-containing and air stable organic positive electrode chemistries. Decades-long experimental and theoretical research in the field resulted in only few recent examples of Li-reservoir materials, all relying on the archetypal carbonyl redox chemistry. Here, we extend the chemical space of organic Li-ion positive electrode materials with a new class of conjugated sulfonamides (CSA) and show that the electron delocalization on the sulfonyl groups endows the resulting CSAs with intrinsic oxidation and hydrolysis resistance while handled in ambient air, yet displaying reversible electrochemistry for charge storage. The formal redox potential of the uncovered CSAs chemistries spans a wide range between 2.85 -3.45 V (vs. Li + /Li 0 ), finely tuneable through electrostatic or inductive molecular design. This class of organic Li-ion positive electrode materials is the first one to consequentially challenge the inorganic battery cathodes realm, as this first generation of CSA chemistries already displays gravimetric energy storage metrics comparable to those of stereotypical LiFePO4.

To meet current market demands as well as emerging environmental concerns there is a need to develop less polluting battery technologies.

Metal–organic frameworks (MOFs) have emerged as an important, yet highly challenging class of electrochemical energy storage materials. The chemical principles for electroactive MOFs remain, however, poorly explored because precise chemical and structural control is mandatory. For instance, no anionic MOF with a lithium cation reservoir and reversible redox (like a conventional Li-ion cathode) has been synthesized to date. Herein, we report on electrically conducting Li-ion MOF cathodes with the generic formula Li2-M-DOBDC (wherein M = Mg2+ or Mn2+; DOBDC4– = 2,5-dioxido-1,4-benzenedicarboxylate), by rational control of the ligand to transition metal stoichiometry and secondary building unit (SBU) topology in the archetypal CPO-27. The accurate chemical and structural changes not only enable reversible redox but also induce a million-fold electrical conductivity increase by virtue of efficient electronic self-exchange facilitated by mix-in redox: 10–7 S/cm for Li2-Mn-DOBDC vs 10–13 S/cm for the isoreticular H2-Mn-DOBDC and Li2-Mg-DOBDC, or the Mn-CPO-27 compositional analogues. This particular SBU topology also considerably augments the redox potential of the DOBDC4– linker (from 2.4 V up to 3.2 V, vs Li+/Li0), a highly practical feature for Li-ion battery assembly and energy evaluation. As a particular cathode material, Li2-Mn-DOBDC displays an average discharge potential of 3.2 V vs Li+/Li0, demonstrates excellent capacity retention over 100 cycles, while also handling fast cycling rates, inherent to the intrinsic electronic conductivity. The Li2-M-DOBDC material validates the concept of reversible redox activity and electronic conductivity in MOFs by accommodating the ligand’s noncoordinating redox center through composition and SBU design.

Raising the operating potential of the organic positive electrode materials is a crucial challenge if they are to compare with lithium-ion inorganic counterparts. Although many efforts have been directed on tuning through substituent electronic effect, the chemistries than can operate above 3 V vs Li + /Li 0 , and thus be air stable in the Li-reservoir form (alike the conventional inorganic Liion positive electrode materials) remain finger-counted. Herein, we report on a new n-type organic Li-ion positive electrode materialthe tetralithium 2,5dihydroxy-1,4-benzenediacetatewith a remarkably high redox potential of 3.35 V vs Li + /Li attained notably in the solid phase. The origin of the high-energy content in this quinone derivative is found in a stereoelectronic chameleonic effect with an intramolecular conformation change and charge modulation leading to a redox potential increase of 650 mV in the solid state as compared to the same chemistry tested in solution (2.70 V vs Li + /Li). The conformational dependent electroactivity rationale is supported by electrochemical and crystallography analysis, comparative infrared spectroscopy, and DFT calculation. We identify and make a linear correlation between the enolate vibrational modes and the redox potential, with general applicability for possibly other phenolate redox chemistries. Owing to these effects, this lithiated quinone is stable in ambient air and can be processed and handled alike the conventional inorganic Li-ion positive electrode materials. Whereas intrinsic to high voltage operation stability issues remain to be solved for practical implementation, our fundamental in nature and proof-of-concept study highlights the strong amplitude of through-space charge modulation effects in designing new organic Li-ion positive electrode chemistries with practical operating potential. 46For all these reasons, the organic battery field has 47

Thanks to their versatility and flexibility, EOMs have shown broad applicability as bulky solid [3] or dissolved [4,5] active material, in aqueous [6][7][8] or non-aqueous electrolyte, [9][10][11] for portable and stationary batteries, respectively. In practice, OEMs are explored as main active materials in LIBs, [12] beyond Li systems (e.g., hydrogen, [13,14] Na-ion, [15][16][17][18][19] K-ion, [20][21][22][23][24] and multivalent batteries like magnesium, [25,26] zinc, [27] or aluminum [28,29] ) and also redox flow batteries; [30] or as supporting active materials such as redox mediators for Li-O 2 batteries, [31] Li-source sacrificial materials for Li-ion capacitor [32] and redox electrolytes for high-energy supercapacitors. [33] In contrast to the state-of-the-art inorganic materials, whose reactivity is based on redox of transition metal center and consequently Li + de/insertion, [34,35] the redox reaction of EOMs is based on the charge state change of the redox moiety, [12] for which the charge compensation during redox can be either made by cations, referring to n-type systems, or by anions, belonging then to p-type system, according to the proposed Hünig's classification. [36,37] The richness of organic chemistry coupled with molecular modifications have provided thus far a plethora of molecules and architectures operating within a large potential window with high specific capacities, extended cycling stability and high cycling rate. This has enabled building a broad database of electroactive compounds for both positive and negative electrode applications. Organic positive electrode materials (OPEMs) certainly benefit from larger attention since there are more possibilities to explore, for example, conducting polymers, [38,39] nitroxides, and other stable organic radicals, [40][41][42][43] sulfur compounds, [11] as well as conjugated amines, [44][45][46] conjugated sulfonamides, [47] nitro-aromatics, [48] and carbonyls. [49,50] The latter being certainly the most explored category owing to major advances attained so far but also to opportunities for further improvements to attain simultaneously high energy and power densities combined with good cycling stability. [12] On the opposite side, the chemical library is less rich for organic negative electrode materials (ONEMs), primarily due to much focus on positive electrode chemistries, for which many issues and strategies are to be addressed and explored, respectively. Today, the ONEMs database counts fewer redox families as OPEMs one, with also less specific chemistries within each class. To cite some: the most studied conjugated dicarboxylates, [51] Hückel-stabilized Schiff base, [52] nitrogen-redox azo

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Over the past few years, solid-state electrolytes (SSEs) have attracted tremendous attention due to their credible promise toward high-energy batteries. In parallel, organic battery electrode materials (OBEMs) are gaining momentum as strong candidates thanks to their lower environmental footprint, flexibility in molecular design and high energy metrics. Integration of the two constitutes a potential synergy to enable energy-dense solidstate batteries (SSBs) with high safety, low cost, and long-term sustainability. In this Review, we present the technological feasibility of combining OBEMs with SSEs along with the possible cell configurations that may result from this peculiar combination. We provide an overview of organic SSBs and discuss their main challenges. We analyze the performance-limiting factors and the critical cell design parameters governing cell-level specific energy and energy density. Lastly, we propose guidelines to achieve 500 Wh kg −1 cell-level specific energy with solid-state Li−organic batteries.