Lithium-ion batteries (LIBs) have become one of the best solutions to the energy storage issue in modern society. However, the battery materials and device development are both complex, and involve multivariable problems. Traditional trial-and-error approach, which relies on researchers to conduct experiments, has encountered bottlenecks in the improvement of the battery performance. Artificial intelligence (AI) is the most potential technology to deal with this issue due to its powerful high-speed and capabilities of processing massive data. In particular, the capability of machine learning (ML) algorithms in assessing multidimensional data variables and discovering patterns in the sets are expected to assist researchers in discovering patterns and elucidating the mechanisms of material synthesis and device fabrication. This review summarizes various challenges encountered in traditional research methods of LIBs and introduces the applications of AI in battery material research, battery device design and manufacturing, material and device characterizations, and battery cycle life and safety assessment in detail. Most importantly, we present the challenges faced by AI and ML in battery research, and discuss the shortcomings and prospects of their applications. We believe that a closer collaboration among experimentalists, modeling specialists, and AI experts in the future will greatly facilitate AI and ML methods for solving battery and materials problems that are difficult to be solved by traditional methods.

Lithium-sulfur (Li-S) batteries are deemed as high-promising next-generation energy storage technique due to their ultrahigh theoretical energy density, where the sulfur cathodes with high specific capacity guarantee the energy density advantage and directly determine the battery performances. After decades of exploration, the most promising sulfur cathodes are sulfur/carbon composite (S/C) cathodes and sulfurized polyacrylonitrile (SPAN) cathodes. In this manuscript, recent advances on S/C and SPAN cathodes in Li-S batteries are comprehensively reviewed. The electrochemical reaction circumstances on S/C and SPAN cathodes are firstly introduced and compared to reveal the working mechanisms of the two types of Li-S batteries. The S/C cathodes mainly undergo solid-liquid-solid multi-phase conversion processes with typical double-plateau charge-discharge polarization curves. In comparison, the SPAN cathodes follow solid-solid conversion and exhibit single-plateau charge-discharge characteristics. Following that, key challenges and targeted optimizing strategies of the S/C and SPAN cathodes are respectively presented and discussed. For Li-S batteries with S/C cathodes, the main optimizing strategies are electrode structure modification, efficient electrocatalyst design, and redox comediation. For SPAN cathodes, the main optimizing strategies are electrode structure modification, morphology regulation by co-polymerization, heteroatom doping at molecular level, and extrinsic redox mediation. At last, current research status of Li-S batteries with S/C or SPAN cathodes are systematically analyzed through the comparison of several battery parameters, and perspectives on challenges and opportunities of S/C and SPAN cathodes in Li-S batteries are presented to guide future researches.

The continuous development of the global energy structure transformation has put forward higher demands upon the development of batteries. The improvements of the energy density have become one of the important indicators and hot topic for novel secondary batteries. The energy density of existing lithium-ion battery has encountered a bottleneck due to the limitations of material and systems. Herein, this paper introduces the concept and development of multi-electron reaction materials over the past twenty years. Guided by the multi-electron reaction, light weight electrode and multi-ion effect, current development strategies and future trends of high-energy-density batteries are highlighted from the perspective of materials and structure system innovation. Typical cathode and anode materials with the multi-electron reactions are summarized from cation-redox to anion-redox, from intercalation-type to alloying-type, and from liquid systems to solid-state lithium batteries. The properties of the typical materials and their engineering prospects are comprehensively discussed, and additionally, the application potential and the main challenges currently encountered by solid-state batteries are also introduced. Finally, this paper gives a comprehensive outlook on the development of high-energy-density batteries.

Ionic liquid (IL) electrolyte-based supercapacitors (SCs) have advantages of high operating voltage window, high energy density and nonflammability, as compared to conventional acetonitrile-based organic electrolyte SCs, and are typically suitable for the large-scale energy storage in the era of carbon neutrality full of renewable, but unstable electricity. However, current efforts were concentrated on the study with coin-cell type of IL-SCs, and less has been reported on the pouch type of IL-SCs for a long cycling time yet. To fabricate a reliable SC for the life time test or for the accelerated aging test under high temperature, one should concern the excellent contact in the current collector/electrode interface to minimize the charge transfer resistance. In the present work, the carbon-Al interfacial effect was studied in the new SC system with Al foam as a current collector coated or painted by different carbon layers. Uniform amorphous carbon layer on Al foam was obtained from carbonization of epoxy resin film, giving a strong interaction of Al and carbon phase, as compared to that of the Al foam adhered with graphene by PVDF. In addition, to fully explore the potential of ILs electrolyte with large ion size, mesoporous carbon electrode was adopted here for a rapid ion diffusion across mesopores. Thus, the new structure SCs pouch consisting of mesoporous carbon electrode, ILs electrolyte and carbon coated-3D Al foam current collector was for the first time fabricated in the present work. Based on the as-made different pouches with capacity of 37 F, their time dependent electrochemical properties, including cyclic voltammetric (CV) response, galvanostatic charge and discharge behaviors, capacitance, contact resistance, and electrochemical impedance spectroscopic (EIS) characteristics were studied by accelerating aging test at 65 ^oC for 500 h at 3 V. The former pouch of Al foam coated with amorphous carbon layer exhibited far higher capacitance retention as compared to the pouch of Al foam adhered with graphene layer. Detailed fitting of ESR was made, and the contact resistance, charge transfer resistance, and Warburg resistance were analyzed thoroughly, providing deep insight into the strong C-Al interface effect on the high and stable performance of SCs with high energy density. Characterization of electrode sheet before and after 500 h aging test confirmed the above results. The high temperature and high voltage condition made the graphene-pasted Al foam unreliable. But the in situ coated carbon layer on Al foam exhibited relatively strong interaction and a reliable structure for the stable operation of the SCs pouch during the aging test. These solid data provide sufficient information for the further optimization of the high voltage SCs toward high energy density, high power density and long cycling time.

Sulfurized polyacrylonitrile (SPAN) is regarded as an attractive cathode candidate of lithium-sulfur (Li-S) batteries for its non-dissolution mechanism and effective alleviation of polysulfides shuttling issue in Li-S batteries, displaying high utilization of cathode active material, outstanding cycle stability and structural stability. However, the relation between cyclization degree and cycle stability of SPAN is still unveiled. In this work, SPAN-C-V composites were synthesized by co-introduction of CuSO₄ and zinc n-ethyl-n-phenyldithiocarbamate (ZDB) in the co-heating of sulfur and polyacrylonitrile. The co-introduction of CuSO₄ and ZDB reduced the cyclization reaction onset temperature of PAN while increased the C—C/C=C within SPAN-C-V, thus led to an increase in the degree of cyclization of SPAN-C-V, achieving excellent electrochemical performance by simultaneously improving the cyclization degree and increasing the content of sulfur. The SPAN-C-V exhibited an initial reversible capacity of 805 mAh·g^-1 and 601 mAh·g^-1 after 100 cycles with the capacity retention rate of 93% at 0.2 C (1 C = 600 mAh·g^-1). The focus on the cyclization degree of SPAN provides an enlightenment of advanced cathode material.