Nanoporous Polymer‐Ceramic Composite Electrolytes for Lithium Metal Batteries

Abstract

Advances in materials that enable high-energy and safe electrochemical storage are understood to be a critical next step for portable electronic devices and for electric vehicles. Progress in both fi elds requires high-density, reliable and safe storage of electrical energy. Rechargeable lithium ion batteries (LIB), due to their high energy density, low internal resistance and minimal memory effects, are currently the most attractive storage technology; [1][2][3][4] they are expected to dominate the marketplace for the foreseeable future. Two well-known drawbacks of current LIB technology stem from the carbonaceous material used to host lithium in the anode. First, the 6/1 C/Li molar ratio in the anode lowers the anode specifi c capacity by more than one order of magnitude: from 3860 mAh g −1 to around 360 mAh g −1 . [ 5 ] It also limits the choice of cathode to relatively low capacity, lithiated compounds, such as lithiated metal oxides, phosphates, and silicates, and presents a barrier to usage of novel, high-storage capacity cathode chemistries based on un-lithiated materials including oxygen, sulfur, and carbon dioxide. [ 6,7 ] A second, less appreciated drawback arises from the small difference in potential that separates lithium insertion into the host and lithium plating onto the host. [ 8 ] Thus, either an overcharged or too quickly charged lithium ion battery can become a lithium metal battery (LMB), wherein the deposited metallic lithium provides the primary storage material in the anode. This means that notorious safety issues associated with non-uniform electrodeposition on metallic lithium anodes, dendrite formation and potential for catastrophic cell failure by internal short circuits, [ 8 ] which are normally associated with LMBs, are also an important concern for LIBs.Development of electrolyte and separator platforms that permit safe and reliable cycling of lithium batteries that utilize metallic lithium anodes provide a potential solution to both of these problems, and is thus an important scientifi c undertaking. A key requirement of such an electrolyte/separator would be the ability to suppress or eliminate uneven electrodeposition of Li and/or to retard subsequent dendrite formation and proliferation during repeated charge-discharge cycles. [ 9 ] Several strategies have been proposed in the older literature for suppressing/managing lithium dendrite growth in LMBs. The list includes electrode coatings that prevent dendrite-induced short-circuits; [ 10 ] introducing so-called solid electrolyte interface (SEI) additives into the electrolyte, which facilitate electrodeposition of Li, [ 11 ] application of external pressure on the lithium metal electrode to "fl atten" the electrode/electrolyte interface. [ 12 ] Mechanical blocking using solid or solid-like electrolytes with suffi ciently high modulus to prevent growth of any formed dendrites [ 13,14 ] has good theoretical support from the model of Monroe and Newman, which shows that an electrolyte with shear modulus around two times that of lithiu...

Dendrite formation in silicon anodes of lithium-ion batteries

“…Future work on this can certainly help us to dene the cause of such uneven charge distributions and the possible routes to mitigate dendrite formation and growth by testing several other electrolytes and additives including solid electrolytes. 73,74 Based on this work, electrolytes must resist pressures higher than 6 GPa to avoid dendrite formation without suffering structural damage.…”

The synergetic effect of lithium polysulfide and lithium nitrate to prevent lithium dendrite growth

“…Although various polymeric and ceramic electrolytes have been demonstrated to suppress lithium dendrite growth [14][15][16][17][18][19][20] , their ionic conductivity, interfacial impedance, mechanical moduli or chemical stability when in contact with metallic lithium were not satisfying and still need further improvement for their implementation. In liquid electrolytes, many additives including organic and inorganic compounds have been used to improve the stability of the SEI layer [21][22][23][24][25] .…”

“…Among various approaches to overcoming the issues of lithium metal anode, it is recognized that electrolyte selection is one of the most dominant factors for stabilizing the lithium metal surface [14][15][16][17][18][19][20][21][22][23][24][25][26][27] . Although various polymeric and ceramic electrolytes have been demonstrated to suppress lithium dendrite growth [14][15][16][17][18][19][20] , their ionic conductivity, interfacial impedance, mechanical moduli or chemical stability when in contact with metallic lithium were not satisfying and still need further improvement for their implementation.…”

Recent Advancements in Polymer-Based Composite Electrolytes for Rechargeable Lithium Batteries

“…This resulting symmetric layer by layer structure can solve issues simultaneously, whereas bi-layered electrolytes can only handle problems on one side. Tu et al [186] developed a sandwich-type composite structure electrolyte (contains liquid electrolyte in working conditions, Fig. 12f) by laminating a high pore density nano-porous γ-Al 2 O 3 sheet between macro-porous PVDF-HFP polymer layers for Li metal batteries and obtained satisfactory results.…”