energy density of commercialized LIBs still cannot meet the requirements for practical applications. Success in these fields will mostly depend on further studying and developing new electrode materials with higher energy density.Li-and Mn-rich layered oxide (LMRO) has been considered as a promising cathode material for the next-generation LIBs due to its high energy density more than 1000 W h kg −1 . [3][4][5][6][7] However, this material also suffers from several fatal drawbacks, such as severe capacity and voltage fading during cycling, [8][9][10] poor rate performance, [5,11,12] large initial irreversible capacity. [13,14] Among these problems, the capacity and voltage fading are the key scientific issues needing to be solved first. It is generally accepted that the structure instability of the LMRO cathode material is one of the intrinsic reasons of its fast capacity and voltage fading. [15][16][17] The phase transformation from layered to spinel structure gives rise to the crystal instability when the LMRO cathode is charged to 4.8 V. [18][19][20][21] The gradual growth of spinel phase during cycling brings about the appearance of a 3.0 V plateau resulting in the voltage fading and then consequently leading to the capacity fading. [22] On the other hand, the capacity fading is also caused by the dissolution of metal elements into the electrolyte. [23,24] Zheng et al. [8] believe that the loss of MnO and NiO results in the capacity loss of the Li[Li 0.2 Ni 0.2 Mn 0.6 ]O 2 electrode because of the formation of spinel phase and subsequent fragmentation and deactivation of transition metal ions. Moreover, the dissolution of metal elements is also due to the corrosion of hydroflouric acid (HF) coming from the reaction of the residual moisture with LiPF 6 . [25] Presently, several strategies have been proposed to suppress the capacity and voltage fading of LMRO cathode material. Surface coating with inert phases is one of the effective ways, such as MnO x , [26,27] Al 2 O 3 , [28,29] MoO 3 , [13] TiO 2 , [30] ZrO 2 , [31] AlPO 4 , [32,33] AlF 3, [34,35] to stabilize the structure of the LMRO cathode materials. Choi et al. [36] reported that the 0.3Li 2 MnO 3 -0.7LiMn 0.60 Ni 0.25 Co 0.15 O 2 cathode material coated by Al 2 O 3 improved not only its discharge capacity but also its cycling stability compared with the prinstine. Guo et al. [37] discovered that the Li 1.2 Ni 0.16 Co 0.068 Mn 0.56 O 2 coated by 3 wt% MnO 2 delivered the capacity retention of 93% after 50 cycles. Chen et al. [38] demonstrated that CePO 4 layer coating onto Poor cycling stability is one of the key scientific issues needing to be solved for Li-and Mn-rich layered oxide cathode. In this paper, sodium carboxymethyl cellulose (CMC) is first used as a novel binder in Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 cathode to enhance its cycling stability. Electrochemical performance is conducted by galvanostatic charge and discharge. Structure and morphology are characterized by X-ray diffraction, scanning electronic microscopy, high-resolution transmiss...

Halide solid electrolytes have been considered as the most promising candidates for practical high-voltage all-solidstate lithium-ion batteries (ASSLIBs) due to their moderate ionic conductivity and good interfacial compatibility with oxide cathode materials. Aliovalent ion doping is an effective strategy to increase the ionic conductivity of halide electrolytes. However, the effects of ion doping on the electrochemical stability window of halide electrolytes and carbon additive on electrochemical performance are still unclear by far. Herein, a series of Zr-doped Li 3−x Er 1−x Zr x Cl 6 halide solid electrolytes (SEs) are synthesized through a mechanochemical method and the effects of Zr substitution on the ionic conductivity and electrochemical stability window are systematically investigated. Zr doping can increase the ionic conductivity, whereas it narrows the electrochemical stability window of the Li 3 ErCl 6 electrolyte simultaneously. The optimized Li 2.6 Er 0.6 Zr 0.4 Cl 6 electrolyte exhibits both a high ionic conductivity of 1.13 mS cm −1 and a high oxidation voltage of 4.21 V. Furthermore, carbon additives are demonstrated to be beneficial for achieving high discharge capacity and better cycling stability and rate performance for halide-based ASSLIBs, which are completely different from the case of sulfide electrolytes. ASSLIBs with uncoated LiCoO 2 cathode and carbon additives exhibit a high discharge capacity of 147.5 mAh g −1 and superior cycling stability with a capacity retention of 77% after 500 cycles. This work provides an in-depth understanding of the influence of ion doping and carbon additives on halide solid electrolytes and feasible strategies to realize highenergy-density ASSLIBs.

Lithium sulfide, Li2S, is a promising cathode material for lithium-sulfur batteries (LSBs), with a high theoretical capacity of 1166 mA h g -1 . However, it suffers from low cyclic stability, low-rate capability and high initial activation potential. In addition, commercially available Li2S is of high cost and of large sizes, over ten microns, which further exacerbates its shortcomings as sulfur cathodes. Exploring new approaches to fabricate small-sized Li2S of low cost and to achieve Li2S cathodes

All-solid-state lithium-ion batteries (ASSLIBs) are considered the most promising option for next-generation high-energy and safe batteries. Herein, a practical all-solid-state battery, with a Li- and Mn-rich layered oxide (LMRO) as the cathode and Li6PS5Cl as the electrolyte, is demonstrated for the first time. The battery delivers the most exceptional performance by far in terms of ultrahigh capacity of 244.5 mA h g–1 and unprecedented cycling stability with an 83% capacity retention after 1000 cycles. We discover that the Li6PS5Cl can be reversibly oxidized and reduced within the voltage range 2.0–4.8 V, which is beneficial to the ionic conduction during long-term cycling of ASSLIBs. Moreover, the electronic and ionic conductivities of LMROs are increased by 4 orders of magnitude via precisely tailoring the composition and structure. In addition, the typical dissolution of transition metal, oxygen release, and phase transformation of LMROs in liquid batteries are substantially eliminated in ASSLIBs.

A novel strategy of in situ precipitation and encapsulation of the ErO phase on the Li(LiNiCoMn)O (LNCMO) cathode material for lithium ion batteries is proposed for the first time. The ErO phase is precipitated from the bulk of the LNCMO material and encapsulated onto its entire surface during the calcining process. Electrochemicial performance is investigated by a galvanostatic charge and discharge test. The structure and morphology are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. The results show that an about 10 nm ErO layer is successfully encapsulated onto the entire surface of the LNCMO matrix material. This unique nanoscale ErO encapsulation can significantly prevent the LNCMO cathode material from being corroded by electrolytes and stabilize the crystal structure of the LNCMO cathode during cycling. Therefore, the prepared ErO-coated LNCMO composite exhibits excellent cycling performace and a high initial Coulombic efficiency.