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Micro-sized silicon anodes can significantly increase the energy density of lithium-ion batteries with low cost. However, the large silicon volume changes during cycling cause cracks for both organic-inorganic interphases and silicon particles. The liquid electrolytes further penetrate the cracked silicon particles and reform the interphases, resulting in huge electrode swelling and quick capacity decay. Here we resolve these challenges by designing a high-voltage electrolyte that forms silicon-phobic interphases with weak bonding to lithium-silicon alloys. The designed electrolyte enables micro-sized silicon anodes (5 µm, 4.1 mAh cm−2) to achieve a Coulombic efficiency of 99.8% and capacity of 2175 mAh g−1 for >250 cycles and enable 100 mAh LiNi0.8Co0.15Al0.05O2 pouch full cells to deliver a high capacity of 172 mAh g−1 for 120 cycles with Coulombic efficiency of >99.9%. The high-voltage electrolytes that are capable of forming silicon-phobic interphases pave new ways for the commercialization of lithium-ion batteries using micro-sized silicon anodes. Micro-sized silicon are promising anode materials due to low-cost and high-energy, yet their application is hindered by inaccessible electrolytes. Here, the authors report sulfolane-based electrolytes that form silicon-phobic interphases and enable high-voltage pouch cells to achieve superior cycle life. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes (SPEs) have the potential to meet evolving Li‐ion battery demands, but for these electrolytes to satisfy growing power and energy density requirements, both transport properties and electrochemical stability must be improved. Unfortunately, improvement in one of these properties often comes at the expense of the other. To this end, a "hybrid aqueous/ionic liquid" SPE (HAILSPE) which incorporates triethylsulfonium‐TFSI (S2,2,2) or N‐methyl‐N‐propylpyrrolidinium‐TFSI (Pyr1,3) ionic liquid (IL) alongside H2O and LiTFSI salt to simultaneously improve transport and electrochemical stability is studied. This work focuses on the impact of HAILSPE composition on electrochemical performance. Analysis shows that an increase in LiTFSI content results in decreased ionic mobility, while increasing IL and water content can offset its impact. pfg‐NMR results reveal that preferential lithium‐ion transport is present in HAILSPE systems. Higher IL concentrations are correlated with an increased degree of passivation against H2O reduction. Compared to the Pyr1,3 systems, the S2,2,2 systems exhibit a stronger degree of passivation due to the formation of a multicomponent interphase layer, including LiF, Li2CO3, Li2S, and Li3N. The results herein demonstrate the superior electrochemical stability of the S2,2,2 systems compared to Pyr1,3 and provide a path toward further enhancement of HAILSPE performance via composition optimization. [ABSTRACT FROM AUTHOR]

A single-crystalline Ni-rich (SCNR) cathode with a large particle size can achieve higher energy density, and is safer, than polycrystalline counterparts. However, synthesizing large SCNR cathodes (>5 μm) without compromising electrochemical performance is very challenging due to the incompatibility between Ni-rich cathodes and high temperature calcination. Herein, we introduce Vegard's Slope as a guide for rationally selecting sintering aids, and we successfully synthesize size-controlled SCNR cathodes, the largest of which can be up to 10 μm. Comprehensive theoretical calculation and experimental characterization show that sintering aids continuously migrate to the particle surface, suppress sublattice oxygen release and reduce the surface energy of the typically exposed facets, which promotes grain boundary migration and elevates calcination critical temperature. The dense SCNR cathodes, fabricated by packing of different-sized SCNR cathode particles, achieve a highest electrode press density of 3.9 g cm−3 and a highest volumetric energy density of 3000 Wh L−1. The pouch cell demonstrates a high energy density of 303 Wh kg−1, 730 Wh L−1 and 76% capacity retention after 1200 cycles. SCNR cathodes with an optimized particle size distribution can meet the requirements for both electric vehicles and portable devices. Furthermore, the principle for controlling the growth of SCNR particles can be widely applied when synthesizing other materials for Li-ion, Na-ion and K-ion batteries. [ABSTRACT FROM AUTHOR]

A 2.9 V intrinsic safe aqueous LiNi0.5Mn1.5O4/Mo6S8 full cell delivers 80 W h kg−1 energy density with capacity decay of 0.075% per cycle (5 C). After the electrolyte pH value adjustment, almost full capacity of LiNi0.5Mn1.5O4 (125 mA h kg−1) is achieved, and 126 W h kg−1 energy density is provided for LiNi0.5Mn1.5O4/Mo6S8 cell, representing one of the highest voltage and energy density among all the aqueous batteries. [ABSTRACT FROM AUTHOR]

A novel bismuth-carbon composite, in which bismuth nanoparticles were anchored in a nitrogen-doped carbon matrix (Bi@NC), is proposed as anode for high volumetric energy density lithium ion batteries (LIBs). Bi@NC composite was synthesized via carbonization of Zn-containing zeolitic imidazolate (ZIF-8) and replacement of Zn with Bi, resulting in the N-doped carbon that was hierarchically porous and anchored with Bi nanoparticles. The matrix provides a highly electronic conductive network that facilitates the lithiation/delithiation of Bi. Additionally, it restrains aggregation of Bi nanoparticles and serves as a buffer layer to alleviate the mechanical strain of Bi nanoparticles upon Li insertion/extraction. With these contributions, Bi@NC exhibits excellent cycling stability and rate capacity compared to bare Bi nanoparticles or their simple composites with carbon. This study provides a new approach for fabricating high volumetric energy density LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] Pre-lithiation is critical for improving the energy density of lithium-ion batteries (LIBs) in practical applications. The pre-lithiation of the high-capacity anode with a large surface area enhances the initial coulombic efficiency (ICE) by compensating the lithium loss from the formation of solid electrolyte interphase (SEI). However, pre-lithiation also affects cycle life, which has been paid little attention to. Here, we first discuss the impact of pre-lithiation on the cycling stability of the full cells, which is closely related to anode material, the degree of pre-lithiation, and the stability of SEI. Then we provide suggestions on how to achieve both high energy density and long cycle life by pre-lithiation. The understanding of the correlation between pre-lithiation and cycling stability sheds light on achieving the optimal performance of lithium-ion batteries from pre-lithiation technology. [ABSTRACT FROM AUTHOR]

Lithium-ion capacitors, as a hybrid electrochemical energy storage device, realize high specific energy and power density within one device, thus attracting extensive attention. Here, hierarchically porous Li 3 VO 4 /C nanocomposite is prepared by a solvo-thermal reaction, followed with a post-annealing process. This composite has macropores at the center and mesopores in the wall, thus effectively promoting electrolyte penetration and structure stability upon cycling simultaneously. Compared to mesoporous Li 3 VO 4 , the enhanced rate capability and specific capacity of hierarchically porous Li 3 VO 4 /C indicate the synergistic effect of mesopores and macropores. Inspired by these results, this composite is coupled with mesoporous carbon (CMK-3) for lithium-ion capacitors, generating a specific energy density of 105 Wh kg −1 at a power density of 188 W kg −1 . Even if the power density increases to 9.3 kW kg −1 , the energy density still remains 62 Wh kg −1 . All these results demonstrate the promising potential of hierarchically porous Li 3 VO 4 in lithium ion capacitors. [ABSTRACT FROM AUTHOR]

High electrochemical reversibility of the TiS 2 anode in “Water-in-Salt” electrolyte (21 m LiTFSI in H 2 O) is demonstrated for the first time. The wide electrochemical window and low chemical activity of H 2 O in the “Water-in-Salt” electrolyte not only significantly enhanced the electrochemical reversibility of TiS 2 but also effectively suppressed the hydrolysis side reaction in the aqueous electrolyte. Paired with a LiMn 2 O 4 cathode, the LiMn 2 O 4 /TiS 2 full cell delivers a relatively high discharge voltage of 1.7 V and an energy density of 78 Wh kg − 1 as well as a satisfactory rate performance. [ABSTRACT FROM AUTHOR]