Cited 0 time in webofscience Cited 0 time in scopus

Effects of alkali carbonate additives and solvent composition on the electrochemical performances of LiNi0.5Mn1.5O4 cathode for lithium-ion batteries

Title
Effects of alkali carbonate additives and solvent composition on the electrochemical performances of LiNi0.5Mn1.5O4 cathode for lithium-ion batteries
Translated Title
Alkali carbonates 첨가제와 전해액 조성이LiNi0.5Mn1.5O4 양극의 전기화학적 성능에 미치는 영향
Authors
Son, Jung Su
DGIST Authors
Son, Jung Su; Lee, Ho Chun; Jeong, Nak Cheon
Advisor(s)
Lee, Ho Chun
Co-Advisor(s)
Jeong, Nak Cheon
Issue Date
2015
Available Date
2015-07-19
Degree Date
2015. 8
Type
Thesis
Keywords
Li-ion batteriesLiNi0.5Mn1.5O4HFalkali carbonateadditivelinear carbonate
Abstract
LiNi0.5Mn1.5O4 (LNMO) is a promising and attractive cathode material due to its high operating voltage, low cost and reasonable capacity. However, the stability issue of electrolytes decomposition under the high operating voltage remains a major hurdle to its wide use. In this study, two approaches are tried to address this problem. In the first place, alkali carbonates including CaCO3, MgCO3, and Li2CO3 were employed as an electrolyte and electrode additives. It is revealed that CaCO3 as an electrode and electrolyte additive greatly improves the cycle performances at 25 oC and 55 oC and self-discharge behavior at 60 oC, which is ascribed to the HF scavenging effect of CaCO3. The surface of the LNMO electrode after electrochemical cycling is analyzed by X-ray photoelectron spectroscopy (XPS), and the HF scavenging effect of alkali carbonates was verified by cyclic voltammetry (CV) analysis. Second, the effects of the type of the linear carbonates (LC: DMC, DEC, EMC) in 1 M LiPF6 EC/LC (3/7, v/v) are investigated. It is found that the LNMO cells with EC/DMC exhibits superior cyclability and coulombic efficiency at 25 oC and 55 oC than those with EC/EMC and EC/DEC. The cells with EC/DMC also show better self-discharge performance than other compositions. The improved electrochemical performances in EC/DMC are attributed to the diminished HF formation compared to the others. ⓒ 2015 DGIST
Table Of Contents
I. Inorganic electrolyte and electrode additives for 5 V LiNi0.5Mn1.5O4 -- 1. INTRODUCTION 1 -- 2. METHODS AND MATERIALS -- 2.1. Chemicals 1 -- 2.2. Preparation of electrolytes 2 -- 2.3. Preparation of electrodes and separator 3 -- 2.4. Coin-type cell assembly 3 -- 2.5. Electrochemical performance tests 4 -- 2.6. Self-discharge test 5 -- 2.7. Surface composition analysis of LNMO electrodes 5 -- 2.8. Cyclic voltammetry 5 -- 3. RESULTS -- 3.1 The effect of the electrode additive alkali carbonate on cell performance 6 -- 3.2 The effect of the electrolyte additive alkali carbonate on cell performance 11 -- 3.3 Surface composition analysis of LNMO electrodes 14 -- 3.4 The effect of the electrolyte additive alkali carbonate as an HF scavenger 18 -- 4. CONCLUSION 18 -- -- II. Linear carbonate effect for 5 V LiNi0.5Mn1.5O4 -- 1. INTRODUCTION 20 -- 2. METHODS AND MATERIALS -- 2.1. Chemicals 22 -- 2.2. Preparation of electrolytes 22 -- 2.3. Preparation of electrodes and separator 23 -- 2.4. Coin-type cell assembly 23 -- 3. RESULTS -- 3.1 The effect of the linear carbonates on cell performance 23 -- 3.2 The effect of the linear carbonates on self-discharge test 27 -- 3.3 Surface composition analysis of LNMO electrodes with linear carbonates 28 -- 3.4 LiNi0.5Mn1.5O4 / lithium foil cell EIS test 31 -- 4. CONCLUSION 32 -- -- Reference 33
URI
http://dgist.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002067777
http://hdl.handle.net/20.500.11750/1411
DOI
10.22677/thesis.2067777
Degree
Master
Department
Energy Systems Engineering
University
DGIST
Files:
Collection:
Energy Science and EngineeringThesesMaster


qrcode mendeley

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE