Nickel-rich layered oxide cathode (LiNi x Co y Mn 1− x − y O 2 , x > 0.5, NCM) shows substantial potential for applications in longer-range electrical vehicles. However, the rapid capacity decay and serious safety concerns impede its practical viability. This work provides a hydrogen-bonded organic framework (HOF) modification strategy to simultaneously improve the electrochemical performance, thermal stability and incombustibility of separator. Melamine cyanurate (MCA), as a low-cost and reliable flame-retardant HOF, was implemented in the separator modification layer, which can prevent the battery short circuit even at a high temperature. In addition, the supermolecule properties of MCA provide unique physical and chemical microenvironment for regulating ion-transport behavior in electrolyte. The MCA coating layer enabled the nickel-rich layered oxide cathode with a high-capacity retention of 90.3% after 300 cycles at 1.0 C. Collectively, the usage of MCA in lithium-ion batteries (LIBs) affords a simple, low-cost and efficient strategy to improve the security and service life of nickel-rich layered cathodes.
Yang Xia,Jiaojiao Li,Zhen Xiao,Xiaozheng Zhou,Jun Zhang,Hui Huang,Yongping Gan,Xinping He,Wenkui Zhang
All-solid-state lithium batteries (ASSLBs) paired with an argyrodite sulfide solid electrolyte have become a candidate to take the world by storm for achieving high energy and safety. However, the undesirable interface design between a sulfide solid electrolyte and cathode is difficult to address its scalability production challenge. Particularly, the inferior interfacial contact between a sulfide solid electrolyte and cathode is an intractable obstacle for the large-scale commercial application of ASSLBs. Herein, an elaborately designed conformally in situ integration of a sulfide solid electrolyte onto a Ni-rich oxide cathode is proposed to overcome this issue through a facile tape casting method. In this unique integrated electrode structure, the sulfide solid electrolyte intimately makes contact with the Ni-rich oxide cathode, which significantly strengthens the solid–solid interfacial compatibility, as well as decreases the interfacial reaction resistances, thereby enabling rapid Li+ transportation and a stable interfacial structure. As a result, ASSLBs consisting of a sulfide solid electrolyte-integrated Ni-rich oxide cathode and Li anode exhibit high discharge capacity, excellent cyclic stability, and remarkable rate performance, which are superior to the cells with segregated structures composed of a Ni-rich oxide cathode, sulfide solid electrolyte, and Li anode. The features clearly indicate that the advanced interfacial contact between the cathode and solid electrolyte is responsible for ASSLBs with low polarization and fast reaction kinetics. Therefore, this work provides a rational proof-of-concept fabrication protocol for the reliable interfacial structure design of high-performance ASSLBs.
Ying Jiang,Guozhong Lu,Shinuo Kang,Fushan Geng,Bingwen Hu
All-solid-state batteries with ultrathin lithium metal, close to the anode-free solid-state batteries, could achieve high energy density. However, it is not trivial to plate an ultrathin lithium metal layer on a Cu current collector (Cu-CC). In situ electron paramagnetic resonance (EPR) imaging showed that the pre-plating on Cu-CC in a Li–In|Li6PS5Cl|Cu cell without pressure holding produced a lithium metal layer with a small area. However, when a Li–In|Li6PS5Cl|Cu cell was held under a considerable pressure, this cell would produce a lithium metal layer with a large area. The Cu-CC with the ultrathin lithium metal layer of a small surface could be extracted and then assembled with LiNiO2 and Li6PS5Cl to achieve better electrochemical performance compared to that of a large surface, because a small area of the lithium metal layer would lead to fewer side reactions and less consumption of lithium ions. This work suggests the importance of the control of the lithium plating and the observation of lithium plating by in situ EPR imaging.
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