Silicon Oxide Anode Material for High-Capacity Lithium Batteries
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Solution Overview
Problem
Lithium secondary batteries face issues with rapid capacity decline and reduced lifetime due to cracking and pulverization of metallic electrode active materials like Si and Sn, and initial efficiency loss when using their oxides, which form irreversible phases during charge-discharge.
Innovation Solution
An electrode active material comprising a first particulate of SiO and a second particulate of Li4SiO4, where lithium is already contained, reduces the formation of irreversible phases like lithium oxide, minimizing dead volume and improving initial efficiency by using an oxygen-free lithium salt during preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metallic electrode active materials (Si, Sn) are used to achieve higher charge-discharge capacity, then capacity is improved, but cracking and pulverization occur due to severe volume change, causing rapid capacity decline and reduced lifetime
Solution Approach 1:
The patent changes the chemical composition parameter by using metal oxides (SiO, SnO) instead of pure metals, and further modifies it by forming a lithium-containing oxide phase (Li4SiO4) through reaction with lithium salt. This parameter change reduces volume expansion from 300-400% to approximately 100%, preventing cracking and pulverization while maintaining high capacity.
Solution Approach 2:
The patent creates a composite material system consisting of metal oxide particles (first particulate) and lithium-containing oxide phase (second particulate). This composite structure combines the high capacity advantage of metal oxides with the structural stability provided by the lithium-containing phase, resolving the contradiction between capacity and lifetime.
2Reliability
If metal oxide electrode active materials are used to reduce cracking and pulverization, then battery lifetime is improved, but initial efficiency is lower due to formation of irreversible phases like lithium oxide during initial charge-discharge
Solution Approach 1:
The patent performs preliminary action by pre-reacting the metal oxide with lithium salt during the preparation process to form the lithium-containing oxide phase (Li4SiO4) before battery assembly. This preliminary formation reaction eliminates the need for irreversible phase formation during initial battery charge-discharge, thereby improving initial efficiency while maintaining the structural stability benefits of metal oxides.
Solution Approach 2:
The patent converts the harmful effect of oxygen reaction (which forms irreversible lithium oxide phases reducing initial efficiency) into a beneficial process by controlling the reaction between metal oxide and lithium salt to form a stable lithium-containing oxide phase. This transforms what would be a harmful side reaction into a useful pre-formation step that improves both lifetime and initial efficiency.
3Productivity
If oxygen-free lithium salt is used to prepare the electrode active material to prevent additional oxygen inflow during heat treatment, then initial efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies the inert atmosphere principle by conducting the heat treatment process in an oxygen-free or inert atmosphere (such as nitrogen or argon environment). This prevents unwanted oxidation reactions while allowing the desired reaction between metal oxide and lithium salt to proceed, thereby improving initial efficiency without significantly complicating the manufacturing process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the initial efficiency to 50% or greater and reduces volume change during charge-discharge, maintaining high battery capacity and extending battery life by minimizing irreversible phase formation.
Implementation Method 1
When the lithium ions are inserted and released at the cathode and the anode, electrical energy is generated through oxidation and reduction reactions.
Implementation Method 2
use of an electrode active material with a higher capacity is required... metallic Si, Sn, etc., which exhibit higher charge-discharge capacity than the carbonaceous materials and are electrochemically alloyable with lithium
Implementation Method 3
an electrode active material consisting of: first particulate of SiO; and second particulate of Li4SiO4... lithium is already contained in the second particulate before the initial charge-discharge through reaction of lithium with the metal (or metalloid) oxide
Data Source
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AI summary
The disclosure relates to an electrode active material including: (a) first particulate of a metal (or metalloid) oxide alloyable with lithium; and (b) second particulate of an oxide containing lithium and the same metal (or metalloid) as that of the metal (or metalloid) oxide, and to a secondary battery including the electrode active material. When the electrode active material is used as an anode active material, reduced amounts of an irreversible phase such as a lithium oxide or a lithium metal oxide are produced during initial charge-discharge of a battery since lithium is already contained in the second particulate before the initial charge-discharge, and thus a dead volume on the side of the cathode can be minimized and a high-capacity battery can be fabricated.