Rechargeable lithium ion battery (LIB) has dominated the energy market from portable electronics to electric vehicles, but the fast-charging remains challenging. The safety concerns of lithium deposition on graphite anode or the decreased energy density using Li 4 Ti 5 O 12 (LTO) anode are incapable to satisfy applications. Herein, the sulfurized polyacrylonitrile (SPAN) is explored for the first time as a high capacity and safer anode in LIBs, in which the high voltage cathode of LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM-H) is further introduced to configure a new SPAN|NCM-H battery with great fast-charging features. The LIB demonstrates a good stability with a high capacity retention of 89.7% after 100 cycles at a high voltage of 3.5 V (i.e., 4.6 V vs Li + /Li). Particularly, the excellent rate capability is confirmed and 78.7% of initial capacity can still be delivered at 4.0C. In addition, 97.6% of the battery capacity can be charged within 2.0C, which is much higher than 80% in current fast-charging application standards. The feature of lithiation potential (>1.0 V vs Li + /Li) of SPAN avoids the lithium deposition and improves the safety, while the high capacity over 640 mAh g −1 promises 43.5% higher energy density than that of LTO-based battery, enabling its great competitiveness to conventional LIBs.even shorter) has attracted considerable attention, [1][2][3][4][5] because the fast charging is one of the most important parameters for electronics and electric vehicles applications. However, the conventional fast charging LIBs using graphite anode always suffers the problem of lithium deposition, which not only shortens the cycle life but also induces the serious safety concerns (e.g., internal short circuit). This is because the potential of graphite can be reduced to the threshold of metallic lithium deposition [6][7][8] due to the large polarization under high charging current, while the deposited lithium is highly active and can react with electrolyte, leading to the death of lithium and increase of internal resistance with a rapid capacity fading. [9] Although the strategies of designing porous graphite etched by KOH [10] or synthesizing composites with conductive matrix (e.g., vaporgrown carbon fibers, [11] carbon nanotube or graphene [12] ) and 3D sponged carbon nanofiber [13] have been explored to enhance the rate capability, the new issues of low initial coulombic efficiency (CE), thick solid electrolyte interphase (SEI) or limited capacity still hinder their practical applications. Fast Charging BatteriesThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

Surface modification of a cathode (e.g., lithium layered oxide, NCM) has become ever more important in lithium-ion batteries, particularly for pursuing higher energy densities and safety at high voltage. This is because structural degradation of the cathode can be mitigated significantly. Herein, an organic complex is introduced for metal phosphate (e.g., AlPO 4 ) modification through a new film-forming process in nonaqueous solution. This general strategy overcomes the challenge of nonuniform coating in current precipitation methods and then opens a new avenue toward ultrathin surface modification on a molecular scale. As one example, asprepared AlPO 4 -coated NCM exhibits much improved structural and electrochemical stability; meanwhile, thermal runaway can be suppressed significantly in overcharged cells using the modified NCM, demonstrating higher and reliable safety features. The great improvements benefit from the uniform and ultrathin AlPO 4 coating, which inhibits the collapse and conversion of the layered structure to spinel, especially to the rock salt structure at high-voltage conditions, as confirmed by HRTEM and EELS.

The development of rechargeable batteries beyond 300 Wh kg -1 for electric vehicles remains challenging, where low capacity electrode materials (especially graphite anode, 372 Ah kg -1 ) remain as the major bottleneck. Although many high capacity alternatives (e.g., Sibased alloys, metal oxides, or Li-based anode) are being widely explored, the energy density achieved has not exceeded 300 Wh kg -1 . Herein, we present a new empirical model that considers multiple design parameters, besides electrode capacities, including areal loading density, voltage difference, initial capacity balance between anode and cathode, and initial Coulombic efficiency to estimate the achievable energy density. This approach is used to predict battery design that can achieve energy density above 300 Wh kg -1 . The model reveals that the lithium storage capacity of electrode materials is only one of several important factors affecting the ultimate battery energy density. Our model provides a new way to review the current battery systems beyond the prism of electrode capacity and also presents a straightforward guideline to design batteries with higher energy densities.

Electrochemical activation, voltage decay and hysteresis of Li-rich layered cathode probed by various cobalt content. Electrochimica Acta.

Volume deformation of lithium-ion batteries is inevitable during operation, affecting battery cycle life, and even safety performance. Accurate prediction of volume deformation of lithium-ion batteries is critical for cell development and battery pack design. In this paper, a practical approach is proposed to predict the volume deformation of lithium-ion batteries. In the proposed method, the deformation of a full cell is determined as the superposition of the thickness changes of cathodes and anodes, which are induced by the expansion/ contraction of crystal structure during lithiation/de-lithiation. The electrodes' crystal volume changes are calculated based on the evolution of lithium stoichiometry in cathode and anode, which can be identified through the reconstruction of the battery charging voltage profile. Finally, the thickness changes of cathode and anode as well as the deformation of the full cell are predicted. The proposed method can achieve accurate predictions of the deformations of lithium-ion batteries with various chemistries, with the predicted errors less than 10%. Moreover, the proposed method can help to interpret the differences in deformation profiles of batteries with different chemistries, and provide useful guidance for cell development.