Research Article Cite This: ACS Appl. Mater. Interfaces 2018, 10, 13588−13597
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Integrated Interface Strategy toward Room Temperature Solid-State Lithium Batteries Jiangwei Ju,† Yantao Wang,†,‡ Bingbing Chen,† Jun Ma,† Shanmu Dong,† Jingchao Chai,† Hongtao Qu,† Longfei Cui,§ Xiuxiu Wu,§ and Guanglei Cui*,† †
Qingdao Industrial Energy Storage Research Institute, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, People’s Republic of China ‡ School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China § Qingdao University of Science & Technology, Qingdao 266042, People’s Republic of China S Supporting Information *
ABSTRACT: Solid-state lithium batteries have drawn wide attention to address the safety issues of power batteries. However, the development of solid-state lithium batteries is substantially limited by the poor electrochemical performances originating from the rigid interface between solid electrodes and solid-state electrolytes. In this work, a composite of poly(vinyl carbonate) and Li10SnP2S12 solid-state electrolyte is fabricated successfully via in situ polymerization to improve the rigid interface issues. The composite electrolyte presents a considerable room temperature conductivity of 0.2 mS cm−1, an electrochemical window exceeding 4.5 V, and a Li+ transport number of 0.6. It is demonstrated that solid-state lithium metal battery of LiFe0.2Mn0.8PO4 (LFMP)/composite electrolyte/Li can deliver a high capacity of 130 mA h g−1 with considerable capacity retention of 88% and Coulombic efficiency of exceeding 99% after 140 cycles at the rate of 0.5 C at room temperature. The superior electrochemical performance can be ascribed to the good compatibility of the composite electrolyte with Li metal and the integrated compatible interface between solid electrodes and the composite electrolyte engineered by in situ polymerization, which leads to a significant interfacial impedance decrease from 1292 to 213 Ω cm2 in solid-state Li−Li symmetrical cells. This work provides vital reference for improving the interface compatibility for room temperature solid-state lithium batteries. KEYWORDS: solid-state lithium batteries, interface compatibility, sulfide solid electrolyte, poly(vinyl carbonate), in situ polymerization
1. INTRODUCTION
These properties enable the SEs to compatibly match high voltage cathode and low voltage lithium metal anode simultaneously, endowing SLBs promising high energy density and security. In addition, as another very important advantage, compared to liquid electrolytes, solid-state electrolytes can avoid the dissolution of active materials during cycles.7,8 Development of SEs have progressed rapidly in recent years, and favorable room temperature ionic conductivity has been presented in lithium garnets, NASICON-type oxides, perovskite, and sulfides based on the Li2S:P2S5 system.9−12
Lithium-ion batteries (LIBs) are changing our life all over the world in many aspects, such as in automobiles, grids, and electric vehicles. However, flammable and volatile liquid electrolytes (LEs) raise the critical safety issues of LIBs.1−3 In addition, the LEs usually are not well compatible with high voltage cathode or low voltage lithium metal anode due to limited high voltage stability or lithium dendrite growth, respectively. The practical energy densities of LIBs hence have seen their limits. Solid-state lithium batteries (SLBs) without LEs are considered to be the ultimate solution. Consequently, their key materials, solid-state electrolytes (SEs), have drawn increasing attention due to their high Young’s modulus, wide electrochemical window, and superior thermal stability.4−6 © 2018 American Chemical Society
Received: February 6, 2018 Accepted: April 5, 2018 Published: April 5, 2018 13588
DOI: 10.1021/acsami.8b02240 ACS Appl. Mater. Interfaces 2018, 10, 13588−13597
Research Article
ACS Applied Materials & Interfaces Table 1. Li+ Conductivity for Different SEs and the Corresponding SLBs Performance solid-state electrolytes type garnet NASICON thio-LISICON antiperovskite perovskite polymer−garnet polymer−thio-LISICON a
composition Li6.4La3Zr1.4Ta0.6O12 Li1.5Al0.5Ge1.5(PO4)3 Li10GeP2S12 Li3OCl Li0.5La0.5TiO3 PEO:12 vol % Li6.4La3Zr1.4Ta0.6O12 PVCA:1 wt % Li10SnP2S12
solid-state lithium batteries Li+ conductivity (mS cm−1) a
1.6 at RT 0.18 at RT 12 at RT 0.20 at RT 1.0 at RT 0.21 at 30 °C 0.20 at 30 °C
cathode/anode
performance
ref
LFP /Li sulfur/Li LNMOc/Li LCOd/graphite
0.05 C at 60 °C 0.1 C at RT 7.3 mA g−1 at RT 10 mA g−1 at RT
LFP or LFMP/Li LFMP/Li
0.1 C at 60 °C 0.5 C at 30 °C
Du et al.4 Wang et al.5 Oh et al.9 Lü et al.13 Inaguma et al.11 Zhang et al.10 this work
b
RT, room temperature. bLFP, LiFePO4. cLNMO, LiNi0.5Mn1.5O4. dLCO, LiCoO2.
Vinylene carbonate (VC) is one typical solid electrolyte interface (SEI) additive to enhance the interfacial compatibility toward lithium anode and high voltage cathode, which can be polymerized into poly(vinyl carbonate) (PVCA).26 In our previous work, PVCA was fabricated successfully via in situ polymerization. It has been proven to be stable exceeding 4.5 V vs Li+/Li, which is verified by matching high voltage cathode LiCoO2.27 These advantages suggest PVCA is a promising SE candidate for high energy density SLBs. However, the inferior ionic conductivity of PVCA (
