Emerging fields such as 3C products, robots, e-tools, EVs, E-ships, E-airplanes, and energy storage rely on advanced batteries for their development. Lithium-ion battery (LIB) has been a ground-breaking technology that won the 2019-Chemistry Nobel Prize, but it cannot meet the ever-growing demands for higher energy density, safety, cycle stability, and rate performance. Therefore, new advanced materials and technologies are needed for next-generation batteries. This Special Topic issue of Applied Physics Letters “New Technologies and New Applications of Advanced Batteries” features recent advances in new materials, technologies, and applications of batteries that have the potential to revolutionize the field and enable more challenging applications. This special collection published 36 articles in 2022–2023, covering developments in experimental and computational/numerical simulation studies on attractive battery materials/technologies including solid-state electrolytes/batteries, Li–S battery, Li–Se battery, Li–O2, Li metal/silicon-based batteries, and Na-ion batteries. The highlights of articles in this special collection are discussed herein in this editorial.
LIBs have been the dominant electrochemical energy-storage technology/device since its commercialization in 1990s. In commercial LIBs, LiFePO4, LiCoO2, and lithium nickel manganese cobalt oxide (NMC)1 compounds are widely used as cathodes, with graphite still almost exclusively used as anode. As the energy density and capacity performance of these electrode materials are approaching their limits, high-performance electrodes that go beyond traditional LIBs are urgently needed. Batteries with Li metal/Si anodes and conversion-type cathodes (e.g., S, Se, and O2) have attracted tremendous attention, as the calculated energy density of these batteries is several times higher than that of the traditional LIBs. However, the dissolution and shuttle effect of polysulfide (polyselenium) hinders practical application of Li–S/Li–Se batteries. One of the effective methods to solve this problem is to introduce a functionalized interlayer. Liang et al.2 constructed a free-standing N-doped-carbon-nanofiber interlayer embedded with bimetallic CoNi(CoNi@N-CNFs), which can not only improve the electronic conductivity of the sulfur cathode but also effectively adsorb the dissolvable polysulfides and promote conversion reactions between sulfur species. Moreover, Xu et al.3 revealed that metal-organic framework (MOF)-derived nanoporous carbon with embedded cobalt nanoparticles (NPCo/C) can effectively suppress the shuttling of polysulfides. The abundant exposed Co active sites in NPCo/C are believed to immobilize polysulfides and accelerate sulfur redox kinetics. According to the study of Meng et al.,4 MXene/Co3O4–CNT film interlayer is also valid for the chemisorption of polysulfides. In Li–Se battery, Xie et al.5 found that by adding redox mediator additives that is composed of 1,4-benzenedithiol and benzeneselenol in the electrolyte, the redox kinetics were accelerated and the shuttle effect of polyselenides was suppressed. As for lithium–oxygen batteries, it is important to regulate the adsorption behavior of oxygen-containing intermediates and improve the reaction kinetics. In terms of this, Lei et al.6 introduced amorphous NiCo2O4 nanosheets in Li–O2 battery. Due to the improved electron density distribution around metal sites, the Li–O2 battery demonstrated a low overpotential and an ultralong lifetime. Liu et al.7 combined Li-rich layered-oxide cathodes with O2 cathodes and found their synergistic effect on cell performance. This battery has the combining advantages of intercalation and conversion-type cathodes. Another promising conversion-type cathode is transition-metal fluoride8,9 or sulfide (i.e., MxSy, M = Ti, Fe, Co, Ni, Mo, etc.),10 which has much higher specific capacity and lower cost. To suppress their huge volume change during cycling, Chen et al.11 introduced polyacrylonitrile (PAN) binder. Due to its high adhesion strength, a stable cycling was achieved. In terms of the anode side, graphite anode is being gradually replaced by high-capacity silicon-based anodes, and Li metal anode is under intense investigation. Compared with the “zero-strain” Li4Ti5O12 anode,12 Si-based anodes have the problem of enormous volume change and concomitant detrimental side reactions with organic electrolytes. To improve the electrochemical/chemical stability of Si anode toward electrolyte, Chen et al.13 constructed an ultrathin double-shell interphase consisting of an inner VO2 nanoshell and an outer C nanoshell. This interphase prevented the direct contact between electrolyte and Si, thus improving the electronic conductivity of anodes. To further study the chemical/electrochemical properties of silicon-based materials, Yoon et al.14 revealed the mechanism of transition metal-ion crosstalk and its effect on silicon-based batteries. In addition, Huger et al.15 revealed the factors that influenced the lithiation onset of amorphous silicon. As for lithium metal anode, lithium dendrite is known to be the main cause of thermal runaway and explosion hazards caused by internal shorting. One of the effective methods to tackle this problem is to design and regulate the structure/composition of lithium anode. In this Special Collection, Liu et al.16 constructed a mixed ion–electron 3D framework with 3D nanosheets through in situ lithiation and electroplating. This composite anode can promote a stable dendrite-free Li stripping/plating process with low overpotential.
In recent years, solid-state lithium batteries (SSLBs) using solid electrolytes (SEs) have been widely recognized as the key next-generation energy storage technology due to their high safety, high energy density, long cycle life, and wide operating temperature range.17,18 Approximately half of the papers in this issue focus on this topic. The representative SEs include sulfide SEs, oxide SEs, metal-halide SEs, and polymer SEs. Sulfide SEs have the advantages of high ionic conductivities and relatively good mechanical deformability, while the poor air stability19 and narrow electrochemical stability window20 hinders their application in high-energy-density batteries. Ren et al.21 put forward a method combining bond valence-Ewald energy analysis and dynamic decomposition pathway analysis to capture the trade-off between ionic transport and electrochemical stability in inorganic SEs. To further suppress Li dendrite formation, Wu et al.22 performed the oxygen doping method for Li6PS5Cl SE. Due to the formation of Li3OCl at electrolyte/Li interface and the decreased electronic conductivity of SE, the O-doped sulfide SE demonstrated excellent interfacial stability and lithium dendrites suppression capability. Oxide SEs [e.g., garnet-type Li7La3Zr2O12 (LLZO)] have many advantages, such as relatively high ionic conductivity, wide electrochemical stability window, and good chemical stability toward lithium metal. Recently, Ma et al.23 adopted a low-cost Al element doping method to improve the Li+ conductivity of LLZO, and the as-prepared SE demonstrated a high Li+ conductivity of 5.331 × 10−4 S cm−1. To further promote the electrochemical performances of oxide SEs, Zhang et al.24 applied an external magnetic field. They found that due to the improved Li+ diffusion and homogenized lithium deposition in SEs, the ionic conductivity of oxide SEs was increased and the cycle performance of Li symmetric cells was enhanced. To tackle the notorious lithium dendrite problem at the Li/SE interface, Yang et al.25 developed an operando small-angle neutron scattering (SANS) technology to realize real-time monitoring of nanoscale Li filament growth in garnet SE. Furthermore, Zhang et al.26 introduced a Prussian blue interlayer to improve the interfacial stability between garnet SE and Li anode. Due to the mixed-conducting property of the interlayer, the interfacial resistance is significantly reduced and uniform Li diffusion is achieved. Li1+xAlxGe2−x(PO4)3 (LAGP) is another type of a typical oxide SE. Ji et al.27 proposed a low-cost co-precipitation method for synthesizing LAGP to obtain pure and uniform nano-LAGP grains. Metal halide electrolytes have gained much attention due to their high compatibility with high-voltage oxide cathode materials.28 Zheng et al.29 performed vacuum-drying-assisted method and introduced pure Li3InCl6 on LiCoO2 surface to achieve an intimate electrolyte/electrode contact. All-solid-state thin-film lithium batteries are promising in application in small electronic devices. Recently, through magnetron sputtering, Chen et al.30 prepared a TiO2 thin film with a unique amorphous-crystalline heterostructure as an anode in thin-film ASSB, which demonstrated better rate capability and cycling stability. Through similar magnetron sputtering, Dai et al.31 constructed a three-layer SE film based on carbon-doped lithium phosphate oxynitride (LiCPON). The sandwich structure improved the interfacial stability between lithium-metal anode and SE to suppress lithium dendrite formation. Compared with the aforementioned inorganic SEs, the flexible polymer SEs have better interfacial contact with electrodes, lower cost, and ease of large-scale manufacture. According to the report of Liu et al.,32 they prepared a humid-air-stable solid polymer electrolyte (SPE) with a high RT Li+ conductivity (2.08 × 10−4 S cm−1). This technology not only achieved an intimate SE/electrode interfacial contact but also simplified the battery assembly process in air environment. In addition to SPEs, composite polymer electrolytes (CPEs) and gel polymer electrolytes (GPEs) also belong to polymer SEs. CPEs combine the benefits of polymers and inorganic SEs. As reported by Yan et al.,33 a stable CPE can be obtained by adding poly(ethylene oxide) (PEO) and ethylene carbonate (EC) into ceramic electrolyte. According to Gu et al.,34 they infiltrated the poly(ethylene oxide)-based SE into LTO–Li0.33La0.56TiO3 ceramic pellet. These methods all achieved better electrode–electrolyte contact. GPEs consist of polymer matrixes and liquid plasticizers (usually organic LEs). For example, George et al.35 proposed a GPE composed of LiTFSI/G4 liquid electrolyte and PAN (polyacrylonitrile)-PEGMEMA (poly (ethylene glycol) methyl ether methacrylate oligomer). In addition to these mainstream SEs, Du et al.36 performed a systematic computational investigation on lithium triborates as SE through the first-principles density functional theory (DFT) calculation.
For “beyond Li-ion” technology, Na-ion batteries and aqueous Zn-based batteries37 are attractive as they are cost-effective, which is essential for application in large-scale energy storage. At the anode side of Na-ion batteries, Wang et al.38 used highly conductive MXene as a conductive binder for a Ge anode for ultra-long lifetime. Moreover, Lim et al.39 introduced atomic layer deposition-grown Al2O3 on the sodium metal surface to investigate the transport mechanism and potential chemical stability of this artificial SEI. At the cathode side, Yan et al.40 reported a new stable cathode material—Na2FeF4. Furthermore, Xie et al.41 found that Mg/Ti co-doped P2-Na0.67Ni0.28Mg0.05Mn0.62Ti0.05O2 layered oxide was a high-efficiency cathode material for sodium ion batteries. Recently, solid-state sodium electrolytes have gained more attention. In this issue, Zhai et al.42 hybridized ionogel with polymeric poly(ethylene oxide) and inorganic conductor Na3Zr2Si2PO12. Li et al.43 combined grain-boundary engineering and bulk doping to significantly improve the ionic conductivity of Na1+xZr2SixP3–xO12 (0 ≤ x ≤ 3) electrolyte to 1.66 × 10−3 S cm−1 at 30 °C.
In conclusion, this Special Topic Issue presents a collection of new results associated with new technologies and new materials applied in advanced batteries. Emerging progress in this field is advancing rapidly, and we anticipate that this Issue will be of interest for researchers all around the world.